TCSH(1) | General Commands Manual | TCSH(1) |
NAME
tcsh
— C shell
with file name completion and command line editing
SYNOPSIS
tcsh |
[-bcdefFimnqstvVxX ]
[-D name[=value]]
[arg] ... |
tcsh |
-l |
DESCRIPTION
tcsh
is an enhanced but completely
compatible version of the Berkeley UNIX C shell,
csh(1). It is a command language
interpreter usable both as an interactive login shell and a shell script
command processor. It includes a command-line editor (see
The command-line editor
(+)), programmable word completion (see
Completion and listing
(+)), spelling correction (see
Spelling correction (+)),
a history mechanism (see History
substitution), job control (see Jobs) and
a C-like syntax. The NEW FEATURES
(+) section describes major enhancements of tcsh
over csh(1). Throughout this manual,
features of tcsh
not found in most
csh(1) implementations (specifically,
the 4.4BSD csh(1)) are labeled with
‘(+)’, and features which are present in
csh(1) but not usually documented are
labeled with ‘(u)’.
Argument list processing
If the first argument (argument 0) to the shell is
‘-
’ then it is a login shell. A login
shell can be also specified by invoking the shell with the
-l
flag as the only argument.
The rest of the flag arguments are interpreted as follows:
-b
- Forces a “break” from option processing, causing any further shell arguments to be treated as non-option arguments. The remaining arguments will not be interpreted as shell options. This may be used to pass options to a shell script without confusion or possible subterfuge. The shell will not run a set-user ID script without this option.
-c
- Commands are read from the following argument (which must be present, and
must be a single argument), stored in the
command
shell variable for reference, and executed. Any remaining arguments are placed in theargv
shell variable. -d
- The shell loads the directory stack from ~/.cshdirs as described under Startup and shutdown, whether or not it is a login shell. (+)
-D
name[=value]- Sets the environment variable name to value. (Domain/OS only) (+)
-e
- The shell exits if any invoked command terminates abnormally or yields a non-zero exit status.
-f
- The shell does not load any resource or startup files, or perform any command hashing, and thus starts faster.
-F
- The shell uses fork(2) instead of vfork(2) to spawn processes. (+)
-i
- The shell is interactive and prompts for its top-level input, even if it appears to not be a terminal. Shells are interactive without this option if their inputs and outputs are terminals.
-l
- The shell is a login shell. Applicable only if
-l
is the only flag specified. -m
- The shell loads ~/.tcshrc even if it does not
belong to the effective user. Newer versions of
su(1) can pass
-m
to the shell. (+) -n
- The shell parses commands but does not execute them. This aids in debugging shell scripts.
-q
- The shell accepts SIGQUIT (see Signal handling) and behaves when it is used under a debugger. Job control is disabled. (u)
-s
- Command input is taken from the standard input.
-t
- The shell reads and executes a single line of input. A
‘
\
’ may be used to escape the newline at the end of this line and continue onto another line. -v
- Sets the
verbose
shell variable, so that command input is echoed after history substitution. -x
- Sets the
echo
shell variable, so that commands are echoed immediately before execution. -V
- Sets the
verbose
shell variable even before executing ~/.tcshrc. -X
- Is to
-x
as-V
is to-v
. --help
- Print a help message on the standard output and exit. (+)
--version
- Print the version/platform/compilation options on the standard output and
exit. This information is also contained in the
version
shell variable. (+)
After processing of flag arguments, if arguments remain but none
of the -c
, -i
,
-s
, or -t
options were
given, the first argument is taken as the name of a file of commands, or
“script”, to be executed. The shell opens this file and saves
its name for possible resubstitution by
‘$0
’. Because many systems use either
the standard version 6 or version 7 shells whose shell scripts are not
compatible with this shell, the shell uses such a “standard”
shell to execute a script whose first character is not a
‘#
’, i.e., that does not start with a
comment.
Remaining arguments are placed in the argv
shell variable.
Startup and shutdown
A login shell begins by executing commands from the system files
/etc/csh.cshrc and
/etc/csh.login. It then executes commands from files
in the user's home directory: first
~/.tcshrc (+) or, if
~/.tcshrc is not found,
~/.cshrc, then the contents of
~/.history (or the value of the
histfile
shell variable) are loaded into memory,
then ~/.login, and finally
~/.cshdirs (or the value of the
dirsfile
shell variable) (+). The shell may read
/etc/csh.login before instead of after
/etc/csh.cshrc, and ~/.login
before instead of after ~/.tcshrc or
~/.cshrc and ~/.history, if
so compiled; see the version
shell variable. (+)
Non-login shells read only /etc/csh.cshrc and ~/.tcshrc or ~/.cshrc on startup.
For examples of startup files, please consult: http://tcshrc.sourceforge.net
Commands like stty(1) and
tset(1), which need be run only once
per login, usually go in one's ~/.login file. Users
who need to use the same set of files with both
csh(1) and
tcsh
can have only a
~/.cshrc which checks for the existence of the
tcsh
shell variable before using
tcsh
-specific commands, or can have both a
~/.cshrc and a ~/.tcshrc
which source
s (see the builtin command)
~/.cshrc. The rest of this manual uses
~/.tcshrc to mean ~/.tcshrc
or, if ~/.tcshrc is not found,
~/.cshrc.
In the normal case, the shell begins reading commands from the terminal, prompting with
>
(Processing of arguments and the use of the shell to process files containing command scripts are described later.) The shell repeatedly reads a line of command input, breaks it into words, places it on the command history list, parses it and executes each command in the line.
One can log out by typing ^D
on an empty
line, logout
or login
or via
the shell's autologout mechanism (see the autologout
shell variable). When a login shell terminates it sets the
logout
shell variable to
‘normal
’ or
‘automatic
’ as appropriate, then
executes commands from the files /etc/csh.logout and
~/.logout. The shell may drop DTR on logout if so
compiled; see the version
shell variable.
The names of the system login and logout files vary from system to system for compatibility with different csh(1) variants; see FILES.
Editing
We first describe The command-line editor (+). The Completion and listing (+) and Spelling correction (+) sections describe two sets of functionality that are implemented as editor commands but which deserve their own treatment. Finally, Editor commands (+) lists and describes the editor commands specific to the shell and their default bindings.
The command-line editor (+)
Command-line input can be edited using key sequences much like
those used in emacs(1) or
vi(1). The editor is active only when
the edit
shell variable is set, which it is by
default in interactive shells. The bindkey
builtin
can display and change key bindings to editor commands (see
Editor commands (+)).
emacs(1)-style key bindings are
used by default (unless the shell was compiled otherwise; see the
version
shell variable), but
bindkey
can change the key bindings to
vi(1)-style bindings en masse.
The shell always binds the arrow keys (as defined in the
TERMCAP
environment variable) to editor
commands:
unless doing so would alter another single-character binding. One
can set the arrow key escape sequences to the empty string with
settc
to prevent these bindings. The ANSI/VT100
sequences for arrow keys are always bound.
Other key bindings are, for the most part, what
emacs(1) and
vi(1) users would expect and can
easily be displayed by bindkey
, so there is no need
to list them here. Likewise, bindkey
can list the
editor commands with a short description of each. Certain key bindings have
different behavior depending if
emacs(1) or
vi(1)-style bindings are being used;
see vimode
for more information.
Note that editor commands do not have the same notion of a
“word” as does the shell. The editor delimits words with any
non-alphanumeric characters not in the shell variable
wordchars
, while the shell recognizes only
whitespace and some of the characters with special meanings to it, listed
under Lexical structure.
Completion and listing (+)
The shell is often able to complete words when given a unique abbreviation. For example, typing part of a word
ls /usr/lost
complete-word
editor
command. The shell completes the filename /usr/lost to
/usr/lost+found/, replacing the incomplete word with
the complete word in the input buffer. (Note the terminal
‘/’; completion adds a
‘/
’ to the end of completed directories
and a space to the end of other completed words, to speed typing and provide a
visual indicator of successful completion. The
addsuffix
shell variable can be unset to prevent
this.) If no match is found (perhaps /usr/lost+found
doesn't exist), the terminal bell rings. If the word is already complete
(perhaps there is a /usr/lost on your system, or
perhaps you were thinking too far ahead and typed the whole thing) a
‘/
’ or space is added to the end if it
isn't already there.
Completion works anywhere in the line, not at just the end; completed text pushes the rest of the line to the right. Completion in the middle of a word often results in leftover characters to the right of the cursor that need to be deleted.
Commands and variables can be completed in much the same way. For example, typing
em[tab]
em
’ to
‘emacs
’ if
‘emacs
’ were the only command on your
system beginning with ‘em
’. Completion
can find a command in any directory in path
or if
given a full pathname.
Typing
echo $ar[tab]
$ar
’ to
‘$argv
’ if no other variable began with
‘ar
’.
The shell parses the input buffer to determine whether the word
you want to complete should be completed as a filename, command or variable.
The first word in the buffer and the first word following
‘;
’,
‘|
’,
‘|&
’,
‘&&
’, or
‘||
’ is considered to be a command. A
word beginning with ‘$
’ is considered
to be a variable. Anything else is a filename. An empty line is
“completed” as a filename.
You can list the possible completions of a word at any time by
typing ^D
to run the
delete-char-or-list-or-eof
editor command. The shell
lists the possible completions using the ls-F
builtin and reprints the prompt and unfinished command line, for
example:
> ls /usr/l[^D] lbin/ lib/ local/ lost+found/ > ls /usr/l
If the autolist
shell variable is set, the
shell lists the remaining choices (if any) whenever completion fails:
> set autolist > nm /usr/lib/libt[tab] libtermcap.a@ libtermlib.a@ > nm /usr/lib/libterm
If the autolist
shell variable is set to
‘ambiguous
’, choices are listed only
when completion fails and adds no new characters to the word being
completed.
A filename to be completed can contain variables, your own or
others' home directories abbreviated with
‘~
’ (see
Filename substitution) and
directory stack entries abbreviated with
‘=
’ (see
Directory stack
substitution (+)). For example,
> ls ~k[^D] kahn kas kellogg > ls ~ke[tab] > ls ~kellogg/
or
> set local = /usr/local > ls $lo[tab] > ls $local/[^D] bin/ etc/ lib/ man/ src/ > ls $local/
Note that variables can also be expanded explicitly with the
expand-variables
editor command.
delete-char-or-list-or-eof
lists at only
the end of the line; in the middle of a line it deletes the character under
the cursor and on an empty line it logs one out or, if the
ignoreeof
variable is set, does nothing.
M-^D
, bound to the editor command
list-choices
, lists completion possibilities
anywhere on a line, and list-choices
(or any one of
the related editor commands that do or don't delete, list and/or log out,
listed under delete-char-or-list-or-eof
) can be
bound to ^D
with the bindkey
builtin command if so desired.
The complete-word-fwd
and
complete-word-back
editor commands (not bound to any
keys by default) can be used to cycle up and down through the list of
possible completions, replacing the current word with the next or previous
word in the list.
The shell variable fignore
can be set to a
list of suffixes to be ignored by completion. Consider the following:
> ls Makefile condiments.h~ main.o side.c README main.c meal side.o condiments.h main.c~ > set fignore = (.o \~) > emacs ma[^D] main.c main.c~ main.o > emacs ma[tab] > emacs main.c
‘main.c~
’ and
‘main.o
’ are ignored by completion
(but not listing), because they end in suffixes in
fignore
. Note that a
‘\
’ was needed in front of
‘~
’ to prevent it from being expanded
to home
as described under
Filename substitution.
fignore
is ignored if only one completion is
possible.
If the complete
shell variable is set to
‘enhance
’, completion 1) ignores case
and 2) considers periods, hyphens and underscores
(‘.
’,
‘-
’, and
‘_
’) to be word separators and hyphens
and underscores to be equivalent. If you had the following files
comp.lang.c comp.lang.perl comp.std.c++ comp.lang.c++ comp.std.c
and typed
mail -f c.l.c[tab]
mail -f comp.lang.c
mail -f c.l.c[^D]
comp.lang.c
’ and
‘comp.lang.c++
’.
Typing
mail -f c..c++[^D]
comp.lang.c++
’ and
‘comp.std.c++
’.
Typing
rm a--file[^D]
A_silly_file a-hyphenated-file another_silly_file
would list all three files, because case is ignored and hyphens and underscores are equivalent. Periods, however, are not equivalent to hyphens or underscores.
If the complete
shell variable is set to
‘Enhance
’, completion ignores case and
differences between a hyphen and an underscore word separator only when the
user types a lowercase character or a hyphen. Entering an uppercase
character or an underscore will not match the corresponding lowercase
character or hyphen word separator.
Typing
rm a--file[^D]
rm A--file
A_silly_file
’ and typing
rm a__file[^D]
A_silly_file
’ and
‘another_silly_file
’ because the user
explicitly used an uppercase or an underscore character.
Completion and listing are affected by several other shell
variables: recexact
can be set to complete on the
shortest possible unique match, even if more typing might result in a longer
match:
> ls fodder foo food foonly > set recexact > rm fo[tab]
just beeps, because ‘fo
’
could expand to ‘fod
’ or
‘foo
’, but if we type another
‘o
’,
> rm foo[tab] > rm foo
the completion completes on
‘foo
’, even though
‘food
’ and
‘foonly
’ also match.
autoexpand
can be set to run the
expand-history
editor command before each completion
attempt, autocorrect
can be set to spelling-correct
the word to be completed (see
Spelling correction (+))
before each completion attempt and correct
can be
set to complete commands automatically after one hits return.
matchbeep
can be set to make completion beep or not
beep in a variety of situations, and nobeep
can be
set to never beep at all. nostat
can be set to a
list of directories and/or patterns that match directories to prevent the
completion mechanism from stat(2)ing
those directories. listmax
and
listmaxrows
can be set to limit the number of items
and rows (respectively) that are listed without asking first.
recognize_only_executables
can be set to make the
shell list only executables when listing commands, but it is quite slow.
Finally, the complete
builtin command can
be used to tell the shell how to complete words other than filenames,
commands and variables. Completion and listing do not work on glob-patterns
(see Filename substitution),
but the list-glob
and
expand-glob
editor commands perform equivalent
functions for glob-patterns.
Spelling correction (+)
The shell can sometimes correct the spelling of filenames, commands and variable names as well as completing and listing them.
Individual words can be spelling-corrected with the
spell-word
editor command (usually bound to
M-s
and M-S
) and the entire
input buffer with spell-line
(usually bound to
M-$
). The correct
shell
variable can be set to ‘cmd
’ to
correct the command name or ‘all
’ to
correct the entire line each time return is typed, and
autocorrect
can be set to correct the word to be
completed before each completion attempt.
When spelling correction is invoked in any of these ways and the shell thinks that any part of the command line is misspelled, it prompts with the corrected line:
> set correct = cmd > lz /usr/bin CORRECT>ls /usr/bin (y|n|e|a)?
One can answer ‘y
’ or space
to execute the corrected line, ‘e
’ to
leave the uncorrected command in the input buffer,
‘a
’ to abort the command as if
^C
had been hit, and anything else to execute the
original line unchanged.
Spelling correction recognizes user-defined completions (see the
complete
builtin command). If an input word in a
position for which a completion is defined resembles a word in the
completion list, spelling correction registers a misspelling and suggests
the latter word as a correction. However, if the input word does not match
any of the possible completions for that position, spelling correction does
not register a misspelling.
Like completion, spelling correction works anywhere in the line, pushing the rest of the line to the right and possibly leaving extra characters to the right of the cursor.
Editor commands (+)
bindkey
lists key bindings and
bindkey -l
lists and briefly describes editor
commands. Only new or especially interesting editor commands are described
here. See emacs(1) and
vi(1) for descriptions of each
editor's key bindings.
The character or characters to which each command is bound by
default is given in parentheses.
^
character means a control
character and M-
character a
meta character, typed as
escape-
character (or
^
[character) on terminals
without a meta key. Case counts, but commands that are bound to letters by
default are bound to both lower- and uppercase letters for convenience.
Supported editor commands are:
backward-char
(^B
,left
)- Move back a character. Cursor behavior modified by
vimode
. backward-delete-word
(M-^H
,M-^?
)- Cut from beginning of current word to cursor - saved in cut buffer. Word
boundary behavior modified by
vimode
. backward-word
(M-b
,M-B
)- Move to beginning of current word. Word boundary and cursor behavior
modified by
vimode
. beginning-of-line
(^A
,home
)- Move to beginning of line. Cursor behavior modified by
vimode
. capitalize-word
(M-c
,M-C
)- Capitalize the characters from cursor to end of current word. Word
boundary behavior modified by
vimode
. complete-word
(tab
)- Completes a word as described under Completion and listing (+).
complete-word-back
(not bound)- Like
complete-word-fwd
, but steps up from the end of the list. complete-word-fwd
(not bound)- Replaces the current word with the first word in the list of possible completions. May be repeated to step down through the list. At the end of the list, beeps and reverts to the incomplete word.
complete-word-raw
(^X-tab
)- Like
complete-word
, but ignores user-defined completions. copy-prev-word
(M-^_
)- Copies the previous word in the current line into the input buffer. See
also
insert-last-word
. Word boundary behavior modified byvimode
. dabbrev-expand
(M-/
)- Expands the current word to the most recent preceding one for which the
current is a leading substring, wrapping around the history list (once) if
necessary. Repeating
dabbrev-expand
without any intervening typing changes to the next previous word etc., skipping identical matches much likehistory-search-backward
does. delete-char
(not bound)- Deletes the character under the cursor. See also
delete-char-or-list-or-eof
. Cursor behavior modified byvimode
. delete-char-or-eof
(not bound)- Does
delete-char
if there is a character under the cursor orend-of-file
on an empty line. See alsodelete-char-or-list-or-eof
. Cursor behavior modified byvimode
. delete-char-or-list
(not bound)- Does
delete-char
if there is a character under the cursor orlist-choices
at the end of the line. See alsodelete-char-or-list-or-eof
. delete-char-or-list-or-eof
(^D
)- Does
delete-char
if there is a character under the cursor,list-choices
at the end of the line orend-of-file
on an empty line. See also those three commands, each of which does only a single action, anddelete-char-or-eof
,delete-char-or-list
, andlist-or-eof
, each of which does a different two out of the three. delete-word
(M-d
,M-D
)- Cut from cursor to end of current word - save in cut buffer. Word boundary
behavior modified by
vimode
. down-history
(down
,^N
)- Like
up-history
, but steps down, stopping at the original input line. downcase-word
(M-l
,M-L
)- Lowercase the characters from cursor to end of current word. Word boundary
behavior modified by
vimode
. end-of-file
(not bound)- Signals an end of file, causing the shell to exit unless the
ignoreeof
shell variable is set to prevent this. See alsodelete-char-or-list-or-eof
. end-of-line
(^E
,end
)- Move cursor to end of line. Cursor behavior modified by
vimode
. expand-history
(M-space
)- Expands history substitutions in the current word. See
History substitution. See
also
magic-space
,toggle-literal-history
, and theautoexpand
shell variable. expand-glob
(^X-*
)- Expands the glob-pattern to the left of the cursor. See Filename substitution.
expand-line
(not bound)- Like
expand-history
, but expands history substitutions in each word in the input buffer. expand-variables
(^X-$
)- Expands the variable to the left of the cursor. See Variable substitution.
forward-char
(^F
,right
)- Move forward one character. Cursor behavior modified by
vimode
. forward-word
(M-f
,M-F
)- Move forward to end of current word. Word boundary and cursor behavior
modified by
vimode
. history-search-backward
(M-p
,M-P
)- Searches backwards through the history list for a command beginning with
the current contents of the input buffer up to the cursor and copies it
into the input buffer. The search string may be a glob-pattern (see
Filename substitution)
containing ‘
*
’, ‘?
’, ‘[]
’, or ‘{}
’.up-history
anddown-history
will proceed from the appropriate point in the history list. Emacs mode only. See alsohistory-search-forward
andi-search-back
. history-search-forward
(M-n
,M-N
)- Like
history-search-backward
, but searches forward. i-search-back
(not bound)- Searches backward like
history-search-backward
, copies the first match into the input buffer with the cursor positioned at the end of the pattern, and prompts withand the first match. Additional characters may be typed to extend the search,bck:
i-search-back
may be typed to continue searching with the same pattern, wrapping around the history list if necessary, (i-search-back
must be bound to a single character for this to work) or one of the following special characters may be typed:- Key
- Behavior
^W
- Appends the rest of the word under the cursor to the search pattern.
delete
(or any character bound tobackward-delete-char
)- Undoes the effect of the last character typed and deletes a character from the search pattern if appropriate.
^G
- If the previous search was successful, aborts the entire search. If not, goes back to the last successful search.
escape
- Ends the search, leaving the current line in the input buffer.
Any other character not bound to
self-insert-command
terminates the search, leaving the current line in the input buffer, and is then interpreted as normal input. In particular, a carriage return causes the current line to be executed. See alsoi-search-fwd
andhistory-search-backward
. Word boundary behavior modified byvimode
. i-search-fwd
(not bound)- Like
i-search-back
, but searches forward. Word boundary behavior modified byvimode
. insert-last-word
(M-_
)- Inserts the last word of the previous input line
(‘
!$
’) into the input buffer. See alsocopy-prev-word
. list-choices
(M-^D
)- Lists completion possibilities as described under
Completion and listing
(+). See also
delete-char-or-list-or-eof
andlist-choices-raw
. list-choices-raw
(^X-^D
)- Like
list-choices
, but ignores user-defined completions. list-glob
(^X-g
,^X-G
)- Lists (via the
ls-F
builtin) matches to the glob-pattern (see Filename substitution) to the left of the cursor. list-or-eof
(not bound)- Does
list-choices
orend-of-file
on an empty line. See alsodelete-char-or-list-or-eof
. magic-space
(not bound)- Expands history substitutions in the current line, like
expand-history
, and inserts a space.magic-space
is designed to be bound to the space bar, but is not bound by default. normalize-command
(^X-?
)- Searches for the current word in
PATH
and, if it is found, replaces it with the full path to the executable. Special characters are quoted. Aliases are expanded and quoted but commands within aliases are not. This command is useful with commands that take commands as arguments, e.g., ‘dbx
’ and ‘sh -x
’. normalize-path
(^X-n
,^X-N
)- Expands the current word as described under the
‘
expand
’ setting of thesymlinks
shell variable. overwrite-mode
(unbound)- Toggles between input and overwrite modes.
run-fg-editor
(M-^Z
)- Saves the current input line and looks for a stopped job where the file
name portion of its first word is found in the
editors
shell variable. Ifeditors
is not set, then the file name portion of theEDITOR
environment variable (‘ed
’ if unset) and theVISUAL
environment variable (‘vi
’ if unset) will be used. If such a job is found, it is restarted as if ‘fg %job
’ had been typed. This is used to toggle back and forth between an editor and the shell easily. Some people bind this command to^Z
so they can do this even more easily. run-help
(M-h
,M-H
)- Searches for documentation on the current command, using the same notion
of “current command” as the completion routines, and prints
it. There is no way to use a pager;
run-help
is designed for short help files. If the special aliashelpcommand
is defined, it is run with the command name as a sole argument. Else, documentation should be in a file named command.help, command.1, command.6, command.8, or command, which should be in one of the directories listed in theHPATH
environment variable. If there is more than one help file only the first is printed. self-insert-command
(text characters)- In insert mode (the default), inserts the typed character into the input
line after the character under the cursor. In overwrite mode, replaces the
character under the cursor with the typed character. The input mode is
normally preserved between lines, but the
inputmode
shell variable can be set to ‘insert
’ or ‘overwrite
’ to put the editor in that mode at the beginning of each line. See alsooverwrite-mode
. sequence-lead-in
(arrow prefix, meta prefix,^X
)- Indicates that the following characters are part of a multi-key sequence.
Binding a command to a multi-key sequence really creates two bindings: the
first character to
sequence-lead-in
and the whole sequence to the command. All sequences beginning with a character bound tosequence-lead-in
are effectively bound toundefined-key
unless bound to another command. spell-line
(M-$
)- Attempts to correct the spelling of each word in the input buffer, like
spell-word
, but ignores words whose first character is one of ‘-
’, ‘!
’, ‘^
’, or ‘%
’, or which contain ‘\
’, ‘*
’, or ‘?
’, to avoid problems with switches, substitutions and the like. See Spelling correction (+). spell-word
(M-s
,M-S
)- Attempts to correct the spelling of the current word as described under Spelling correction (+). Checks each component of a word which appears to be a pathname.
toggle-literal-history
(M-r
,M-R
)- Expands or unexpands history substitutions in the input buffer. See also
expand-history
and theautoexpand
shell variable. undefined-key
(any unbound key)- Beeps.
up-history
(up
,^P
)- Copies the previous entry in the history list into the input buffer. If
histlit
is set, uses the literal form of the entry. May be repeated to step up through the history list, stopping at the top. upcase-word
(M-u
,M-U
)- Uppercase the characters from cursor to end of current word. Word boundary
behavior modified by
vimode
. vi-beginning-of-next-word
(not bound)- Vi goto the beginning of next word. Word boundary and cursor behavior
modified by
vimode
. vi-eword
(not bound)- Vi move to the end of the current word. Word boundary behavior modified by
vimode
. vi-search-back
(?
)- Prompts with
for a search string (which may be a glob-pattern, as with
?
history-search-backward
), searches for it and copies it into the input buffer. The bell rings if no match is found. Hitting return ends the search and leaves the last match in the input buffer. Hitting escape ends the search and executes the match.vi
mode only. vi-search-fwd
(/
)- Like
vi-search-back
, but searches forward. which-command
(M-?
)- Does a
which
(see the description of the builtin command) on the first word of the input buffer. yank-pop
(M-y
)- When executed immediately after a
yank
or anotheryank-pop
, replaces the yanked string with the next previous string from the killring. This also has the effect of rotating the killring, such that this string will be considered the most recently killed by a lateryank
command. Repeatingyank-pop
will cycle through the killring any number of times.
Lexical structure
The shell splits input lines into words at blanks and tabs. The
special characters ‘&
’,
‘|
’,
‘;
’,
‘<
’,
‘>
’,
‘(
’, and
‘)
’, and the doubled characters
‘&&
’,
‘||
’,
‘<<
’, and
‘>>
’ are always separate words,
whether or not they are surrounded by whitespace.
When the shell's input is not a terminal, the character
‘#
’ is taken to begin a comment. Each
‘#
’ and the rest of the input line on
which it appears is discarded before further parsing.
A special character (including a blank or tab) may be prevented
from having its special meaning, and possibly made part of another word, by
preceding it with a backslash (‘\
’) or
enclosing it in single (‘'
’), double
(‘"
’), or backward
(‘`
’) quotes. When not otherwise
quoted a newline preceded by a ‘\
’ is
equivalent to a blank, but inside quotes this sequence results in a
newline.
Furthermore, all
Substitutions except
History substitution can be
prevented by enclosing the strings (or parts of strings) in which they
appear with single quotes or by quoting the crucial character(s) (e.g.,
‘$
’ or
‘`
’ for
Variable substitution or
Command substitution
respectively) with ‘\
’.
(Alias substitution is no
exception: quoting in any way any character of a word for which an
alias
has been defined prevents substitution of the
alias. The usual way of quoting an alias is to precede it with a backslash.)
History substitution is
prevented by backslashes but not by single quotes. Strings quoted with
double or backward quotes undergo
Variable substitution and
Command substitution, but
other substitutions are prevented.
Text inside single or double quotes becomes a single word (or part of one). Metacharacters in these strings, including blanks and tabs, do not form separate words. Only in one special case (see Command substitution) can a double-quoted string yield parts of more than one word; single-quoted strings never do. Backward quotes are special: they signal Command substitution, which may result in more than one word.
C-style escape sequences can be used in single quoted strings by
preceding the leading quote with ‘$
’.
(+) See Escape sequences (+)
for a complete list of recognized escape sequences.
Quoting complex strings, particularly strings which themselves contain quoting characters, can be confusing. Remember that quotes need not be used as they are in human writing! It may be easier to quote not an entire string, but only those parts of the string which need quoting, using different types of quoting to do so if appropriate.
The backslash_quote
shell variable can be
set to make backslashes always quote
‘\
’,
‘'
’, and
‘"
’ (+). This may make complex
quoting tasks easier, but it can cause syntax errors in
csh(1) scripts.
Escape sequences (+)
The following escape sequences are always recognized inside a
string constructed using ‘$''
’, and
optionally by the echo
builtin command as controlled
by the echo_style
shell variable.
Supported escape sequences are:
- Escape
- Description
\a
- Bell.
\b
- Backspace.
\c
c- The control character denoted by
‘
^c
’ in stty(1). If c is a backslash, it must be doubled. \e
- Escape.
\f
- Form feed.
\n
- Newline.
\r
- Carriage return.
\t
- Horizontal tab.
\v
- Vertical tab.
\\
- Literal backslash.
\'
- Literal single quote.
\"
- Literal double quote.
\
nnn- The character corresponding to the octal number nnn.
\x
nn- The character corresponding to the hexadecimal number nn (1-2 hexadecimal digits).
\x{
nnnnnnnn}
- The character corresponding to the hexadecimal number nnnnnnnn (1-8 hexadecimal digits).
\u
nnnn- The Unicode code point nnnn (1-4 hexadecimal digits).
\U
nnnnnnnn- The Unicode code point nnnnnnnn (1-8 hexadecimal digits).
The implementations of ‘\x
’,
‘\u
’, and
‘\U
’ in other shells may take a
varying number of digits. It is often safest to use leading zeros to provide
the maximum expected number of digits.
Substitutions
We now describe the various transformations the shell performs on the input in the order in which they occur. We note in passing the data structures involved and the commands and variables which affect them. Remember that substitutions can be prevented by quoting as described under Lexical structure.
History substitution
Each command, or “event”, input from the terminal is
saved in the history list. The previous command is always saved, and the
history
shell variable can be set to a number to
save that many commands. The histdup
shell variable
can be set to not save duplicate events or consecutive duplicate events.
Saved commands are numbered sequentially from 1 and stamped with
the time. It is not usually necessary to use event numbers, but the current
event number can be made part of the prompt by placing an
‘!
’ in the
prompt
shell variable.
By default history entries are displayed by printing each parsed
token separated by space; thus the redirection operator
‘>&!
’ will be displayed as
‘> & !
’. The
shell actually saves history in expanded and literal (unexpanded) forms. If
the histlit
shell variable is set, commands that
display and store history use the literal form.
The history
builtin command can print,
store in a file, restore and clear the history list at any time, and the
savehist
and histfile
shell
variables can be set to store the history list automatically on logout and
restore it on login.
History substitutions introduce words from the history list into the input stream, making it easy to repeat commands, repeat arguments of a previous command in the current command, or fix spelling mistakes in the previous command with little typing and a high degree of confidence.
History substitutions begin with the character
‘!
’. They may begin anywhere in the
input stream, but they do not nest. The
‘!
’ may be preceded by a
‘\
’ to prevent its special meaning;
for convenience, a ‘!
’ is passed
unchanged when it is followed by a blank, tab, newline,
‘=
’ or
‘(
’.
History substitutions also occur when an input line begins with
‘^
’; see
History substitution
abbreviation.
The characters used to signal history substitution
(‘!
’ and
‘^
’) can be changed by setting the
histchars
shell variable. Any input line which
contains a history substitution is printed before it is executed.
A history substitution may have an “event specification” (see History event specification), which indicates the event from which words are to be taken, a “word designator” (see History word designators), which selects particular words from the chosen event, and/or a “word modifier” (see History word modifiers), which manipulates the selected words.
History event specification
A history event specification may be one of (with the history
substitution character ‘!
’ shown):
- !Event
- History event specification
!
n- A number, referring to a particular event.
!-
n- An offset, referring to the event n before the current event.
!#
- The current event. This should be used carefully in
csh(1), where there is no check for
recursion.
tcsh
allows 10 levels of recursion. (+) !!
- The previous event, equivalent to
‘
!-1
’. !
s- The most recent event whose first word begins with the string s.
!?
s?
- The most recent event which contains the string s.
The second ‘
?
’ can be omitted if it is immediately followed by a newline.
For example, consider this bit of someone's history list:
9 8:30 nroff -man wumpus.man 10 8:31 cp wumpus.man wumpus.man.old 11 8:36 vi wumpus.man 12 8:37 diff wumpus.man.old wumpus.man
The commands are shown with their event numbers and time stamps. The current event, which we haven't typed in yet, is event 13.
Typing
!11
!-2
Typing
!!
!!
’ can
be abbreviated ‘!
’ if it is followed by
‘:
’, which is described in
History word designators
and History word modifiers.
Typing
!n
n
’.
Typing
!?old?
old
’.
Without word designators or modifiers history references simply expand to the entire event, so we might type
!cp
cp
’ command (event 10) or
!!|more
diff
’ output in the previous
event, 12, scrolled off the top of the screen.
History references may be insulated from the surrounding text with
braces (‘{
’ and
‘}
’) if necessary. For example,
!vdoc
vdoc
’, and, in this example, not find
one, but
!{v}doc
vi
wumpus.mandoc
’ by matching event 11. Even in braces, history
substitutions do not nest.
(+) While csh(1) expands, for example,
!3d
d
’ appended to
it, tcsh
expands it to the last event beginning with
‘3d
’; only completely numeric arguments
are treated as event numbers. This makes it possible to recall events
beginning with numbers. To expand
!3d
!{3}d
History word designators
To select words from an event we can follow the event
specification by a ‘:
’ and a
designator for the desired words. The words of an input line are numbered
from 0, the first (usually command) word being 0, the second word (first
argument) being 1, etc.
The basic word designators are, with columns for a leading
‘:
’ and a leading
‘!
’ (for the abbreviated word
designators - see
History substitution
abbreviation):
:Word | !Word | History word designator |
:0 |
The first (command) word. | |
: n |
The nth argument. | |
:^ |
!^ |
The first argument, equivalent to
‘:1 ’.
|
:$ |
!$ |
The last argument. |
:% |
!% |
The word matched by an
? s?
search.
|
: x- y |
A range of words. | |
:- y |
!- y |
Equivalent to
‘:0- y’.
|
:* |
!* |
Equivalent to ‘:^-$ ’, but returns
nothing if the event contains only 1 word.
|
: x* |
Equivalent to
‘: x-$ ’.
|
|
: x- |
Equivalent to
‘: x* ’,
but omitting the last word (‘$ ’).
|
|
:- |
Equivalent to ‘:0- ’; the command
and all arguments except the last argument. |
Selected words are inserted into the command line separated by single blanks.
For example, the ‘diff
’
command (event 12) in the history list example in
History event
specification,
diff wumpus.man.old
wumpus.man
diff !!:1.old !!:1
:1
’ to select the first argument
from the previous event) or
diff !-2:2 !-2:1
cp
’ command (event 10). If we didn't
care about the order of the ‘diff
’ we
might have typed
diff !-2:1-2
diff !-2:*
The ‘cp
’ command (event 10)
might have been typed
cp wumpus.man !#:1.old
#
’ to refer to the current event.
Typing
!n:- hurkle.man
nroff
’ command (event 9) to expand to
nroff -man hurkle.man
The ‘:
’ separating the event
specification from the word designator can be omitted if the argument
selector begins with a ‘^
’,
‘$
’,
‘%
’,
‘-
’, or
‘*
’.
For example, our ‘diff
’
command (event 12) might have been typed
diff !!^.old !!^
diff !!$.old !!$
!!
’ is abbreviated
‘!
’, an argument selector beginning with
‘-
’ will be interpreted as an event
specification.
A history reference may have a word designator but no event specification. It then references the previous command.
Continuing our ‘diff
’
command example (event 12), we could have typed simply
diff !^.old !^
diff !*
History word modifiers
The word or words in a history reference can be edited, or
“modified”, by following it with one or more modifiers (with
the leading ‘:
’ shown), each preceded
by a ‘:
’:
- :Word
- History word modifier
:h
- Remove a trailing pathname component, leaving the head.
:t
- Remove all leading pathname components, leaving the tail.
:r
- Remove a filename extension ‘.xxx’, leaving the root name.
:e
- Remove all but the extension.
:u
- Uppercase the first lowercase letter.
:l
- Lowercase the first uppercase letter.
:s/
l/
r/
- Substitute l for r.
l is simply a string like r,
not a regular expression as in the eponymous
ed(1) command. Any character may be
used as the delimiter in place of
‘
/
’; a ‘\
’ can be used to quote the delimiter inside l and r. The character ‘&
’ in the r is replaced by l; ‘\
’ also quotes ‘&
’. If l is empty (‘’), the l from a previous substitution or the s from a previous search or event number in event specification is used. The trailing delimiter may be omitted if it is immediately followed by a newline. :&
- Repeat the previous substitution.
:g
- Apply the following modifier once to each word.
:a
(+)- Apply the following modifier as many times as possible to a single word.
‘
:a
’ and ‘:g
’ can be used together to apply a modifier globally. With the ‘:s
’ modifier, only the patterns contained in the original word are substituted, not patterns that contain any substitution result. :p
- Print the new command line but do not execute it.
:q
- Quote the substituted words, preventing further substitutions.
:Q
- Same as ‘
:q
’ but in addition preserve empty variables as a string containing a NUL. This is useful to preserve positional arguments for example:> set args=('arg 1' '' 'arg 3') > tcsh -f -c 'echo ${#argv}' $args:gQ 3
:x
- Like ‘
:q
’, but break into words at blanks, tabs and newlines.
Modifiers are applied to only the first modifiable word (unless
‘:g
’ is used). It is an error for no
word to be modifiable.
For example, the ‘diff
’
command (event 12) in the history list example in
History event
specification,
diff wumpus.man.old
wumpus.man
diff wumpus.man.old
!#^:r
:r
’ to remove
‘.old
’ from the first argument on the
same line (‘!#^
’).
We could type
echo hello out there
echo !*:u
hello
’,
echo !*:au
HELLO
’,
or
echo !*:agu
We might follow
mail -s "I forgot my
password" rot
!:s/rot/root
root
’ (see
History word modifiers and
Spelling correction (+) for
different approaches).
(+) In csh(1) as such, only
one modifier may be applied to each history or variable expansion. In
tcsh
, more than one may be used, for example
% mv wumpus.man /usr/share/man/man1/wumpus.1 % man !$:t:r man wumpus
In csh(1), the result would be
wumpus.1:r
A substitution followed by a
‘:
’ may need to be insulated from it
with braces:
> mv a.out /usr/games/wumpus > setenv PATH !$:h:$PATH Bad ! modifier: $. > setenv PATH !{-2$:h}:$PATH setenv PATH /usr/games:/bin:/usr/bin:.
The first attempt would succeed in
csh(1) but fails in
tcsh
, because tcsh
expects
another modifier after the second ‘:
’
rather than ‘$
’.
History substitution abbreviation
There is a special abbreviation for substitutions;
‘^
’, when it is the first character on
an input line, is equivalent to
‘!:s^
’. Thus, we might follow the
example from History word
modifiers
mail -s "I forgot my
password" rot
^rot^root
!
’.
History editor commands
Finally, history can be accessed through the editor as well as
through the substitutions just described. The
up-history
and down-history
,
history-search-backward
and
history-search-forward
,
i-search-back
and
i-search-fwd
, vi-search-back
and vi-search-fwd
,
copy-prev-word
and
insert-last-word
editor commands search for events
in the history list and copy them into the input buffer. The
toggle-literal-history
editor command switches
between the expanded and literal forms of history lines in the input buffer.
expand-history
and
expand-line
expand history substitutions in the
current word and in the entire input buffer respectively.
Alias substitution
The shell maintains a list of aliases which can be set, unset and
printed by the alias
and
unalias
commands. After a command line is parsed
into simple commands (see Commands) the
first word of each command, left-to-right, is checked to see if it has an
alias. If so, the first word is replaced by the alias. If the alias contains
a history reference, it undergoes
History substitution as
though the original command were the previous input line. If the alias does
not contain a history reference, the argument list is left untouched.
Thus if the alias for ‘ls
’
were
ls -l
ls /usr
ls -l /usr
If the alias for ‘lookup
’
were
grep !^ /etc/passwd
lookup bill
grep bill /etc/passwd
Aliases can be used to introduce parser metasyntax. For example,
alias print 'pr \!* |
lpr'
print
’) which
pr(1)s its arguments to the line
printer.
Alias substitution is repeated until the first word of the command has no alias. If an alias substitution does not change the first word (as in the previous example) it is flagged to prevent a loop. Other loops are detected and cause an error.
Some aliases are referred to by the shell; see Special aliases (+).
Variable substitution
The shell maintains a list of variables, each of which has as
value a list of zero or more words. The values of shell variables can be
displayed and changed with the set
and
unset
commands. The system maintains its own list of
“environment” variables. These can be displayed and changed
with printenv
, setenv
, and
unsetenv
.
(+) Variables may be made read-only with
set -r
set -r
Some variables are set by the shell or referred to by it. For
instance, the argv
variable is an image of the
shell's argument list, and words of this variable's value are referred to in
special ways. Some of the variables referred to by the shell are toggles;
the shell does not care what their value is, only whether they are set or
not. For instance, the verbose
variable is a toggle
which causes command input to be echoed. The -v
command line option sets this variable.
Special shell variables
lists all variables which are referred to by the shell.
Other operations treat variables numerically. The
‘@
’ command permits numeric
calculations to be performed and the result assigned to a variable. Variable
values are, however, always represented as (zero or more) strings. For the
purposes of numeric operations, the null string is considered to be zero,
and the second and subsequent words of multi-word values are ignored.
After the input line is aliased and parsed, and before
each command is executed, variable substitution is performed keyed by
‘$
’ characters. This expansion can be
prevented by preceding the ‘$
’ with a
‘\
’ except within
‘"
’ pairs where it
always occurs, and
within ‘'
’ pairs where it
never
occurs. Strings quoted by ‘`
’ are
interpreted later (see Command
substitution) so ‘$
’ substitution
does not occur there until later, if at all. A
‘$
’ is passed unchanged if followed by
a blank, tab, or end-of-line.
Input/output redirections are recognized before variable expansion, and are variable expanded separately. Otherwise, the command name and entire argument list are expanded together. It is thus possible for the first (command) word (to this point) to generate more than one word, the first of which becomes the command name, and the rest of which become arguments.
Unless enclosed in ‘"
’
or given the ‘:q
’ modifier the results
of variable substitution may eventually be command and filename substituted.
Within ‘"
’, a variable whose
value consists of multiple words expands to a (portion of a) single word,
with the words of the variable's value separated by blanks. When the
‘:q
’ modifier is applied to a
substitution the variable will expand to multiple words with each word
separated by a blank and quoted to prevent later command or filename
substitution.
The editor command expand-variables
,
normally bound to ^X-$
, can be used to interactively
expand individual variables.
Variable substitution metasequences
The following metasequences are provided for introducing variable values into the shell input:
$
name${
name}
- Substitutes the words of the value of variable name, each separated by a blank. Braces insulate name from following characters which would otherwise be part of it. Shell variables have names consisting of letters and digits starting with a letter. The underscore character is considered a letter. If name is not a shell variable, but is set in the environment, then that value is returned (but some of the other forms given below are not available in this case).
$
name[
selector]
${
name[
selector]}
- Substitutes only the selected words from the value of
name. The selector is
subjected to ‘
$
’ substitution and may consist of a single number or two numbers separated by a ‘-
’. The first word of a variable's value is numbered ‘1
’. If the first number of a range is omitted it defaults to ‘1
’. If the last member of a range is omitted it defaults to ‘$#name
’. The selector ‘*
’ selects all words. It is not an error for a range to be empty if the second argument is omitted or in range. $0
- Substitutes the name of the file from which command input is being read. An error occurs if the name is not known.
$
number${
number}
- Equivalent to
‘
$argv[number
’.]
$*
- Equivalent to ‘
$argv
’, which is equivalent to ‘$argv[*]
’.
Except as noted, it is an error to reference a variable which is not set.
The ‘:
’ modifiers described
under History word
modifiers, except for ‘:p
’, can be
applied to the substitutions above. More than one may be used. (+) Braces
may be needed to insulate a variable substitution from a literal
‘:
’ just as with
History word modifiers; any
modifiers must appear within the braces.
Variable substitution without modifiers
The following substitutions cannot be modified with
‘:
’ modifiers:
$?
name${?
name}
- Substitutes the string ‘
1
’ if name is set, ‘0
’ if it is not. $?0
- Substitutes ‘
1
’ if the current input filename is known, ‘0
’ if it is not. Always ‘0
’ in interactive shells. $#
name${#
name}
- Substitutes the number of words in name.
$#
- Equivalent to ‘
$#argv
’. (+) $%
name${%
name}
- Substitutes the number of characters in name. (+)
$%
number${%
number}
- Substitutes the number of characters in
‘
$argv[number
’. (+)]
$?
- Equivalent to ‘
$status
’. (+) $$
- Substitutes the (decimal) process number of the (parent) shell.
$!
- Substitutes the (decimal) process number of the last background process started by this shell. (+)
$_
- Substitutes the command line of the last command executed. (+)
$<
- Substitutes a line from the standard input, with no further interpretation
thereafter. It can be used to read from the keyboard in a shell script.
(+) While csh(1) always quotes
‘
$<
’, as if it were equivalent to ‘$<:q
’,tcsh
does not. Furthermore, whentcsh
is waiting for a line to be typed the user may type an interrupt to interrupt the sequence into which the line is to be substituted, but csh(1) does not allow this. $?<
- Substitutes the number of available bytes from the standard input. (This feature might be non-portable.) (+)
Command, filename and directory stack substitution
The remaining substitutions are applied selectively to the arguments of builtin commands. This means that portions of expressions which are not evaluated are not subjected to these expansions. For commands which are not internal to the shell, the command name is substituted separately from the argument list. This occurs very late, after input-output redirection is performed, and in a child of the main shell.
Command substitution
Command substitution is indicated by a command enclosed in
‘`
’. The output from such a command is
broken into separate words at blanks, tabs and newlines, and null words are
discarded. The output is variable and command substituted and put in place
of the original string.
Command substitutions inside double quotes
(‘"
’) retain blanks and tabs;
only newlines force new words. The single final newline does not force a new
word in any case. It is thus possible for a command substitution to yield
only part of a word, even if the command outputs a complete line.
By default, the shell since version 6.12 replaces all newline and
carriage return characters in the command by spaces. If this is switched off
by unsetting csubstnonl
, newlines separate commands
as usual.
Filename substitution
If a word contains any of the characters
‘*
’,
‘?
’,
‘[
’, or
‘{
’ or begins with the character
‘~
’ it is a candidate for filename
substitution, also known as “globbing”. This word is then
regarded as a pattern (“glob-pattern”), and replaced with an
alphabetically sorted list of file names which match the pattern.
In matching filenames, the character
‘.
’ at the beginning of a filename or
immediately following a ‘/
’, as well
as the character ‘/
’ must be matched
explicitly (unless either globdot
or
globstar
or both are set (+)). The character
‘*
’ matches any string of characters,
including the null string. The character
‘?
’ matches any single character. The
sequence ‘[...]
’ matches any one of
the characters enclosed. Within
‘[...]
’, a pair of characters
separated by ‘-
’ matches any character
lexically between the two.
(+) Some glob-patterns can be negated: The sequence
‘[^...]
’ matches any single character
not specified by the characters and/or ranges of
characters in the braces.
An entire glob-pattern can also be negated with
‘^
’:
> echo * bang crash crunch ouch > echo ^cr* bang ouch
Glob-patterns which do not use
‘?
’,
‘*
’, or
‘[]
’, or which use
‘{}
’ or
‘~
’ (below) are not negated
correctly.
The metanotation ‘a{b,c,d}e
’
is a shorthand for ‘abe ace ade
’.
Left-to-right order is preserved:
/usr/source/s1/{oldls,ls}.c
/usr/source/s1/oldls.c
/usr/source/s1/ls.c
../{memo,*box}
../memo ../box ../mbox
memo
’ was not sorted with the
results of matching ‘*box
’.) It is not
an error when this construct expands to files which do not exist, but it is
possible to get an error from a command to which the expanded list is passed.
This construct may be nested. As a special case the words
‘{
’,
‘}
’, and
‘{}
’ are passed undisturbed.
The character ‘~
’ at the
beginning of a filename refers to home directories. Standing alone, i.e.,
‘~
’, it expands to the invoker's home
directory as reflected in the value of the home
shell variable. When followed by a name consisting of letters, digits and
‘-
’ characters the shell searches for
a user with that name and substitutes their home directory; thus
~ken
/usr/ken
~ken/chmach
/usr/ken/chmach
~
’ is followed by a
character other than a letter or ‘/
’ or
appears elsewhere than at the beginning of a word, it is left undisturbed. A
command like
setenv MANPATH
/usr/share/man:/usr/local/share/man:~/lib/man
It is an error for a glob-pattern containing
‘*
’,
‘?
’,
‘[
’, or
‘~
’, with or without
‘^
’, not to match any files. However,
only one pattern in a list of glob-patterns must match a file (so that,
e.g.,
rm *.a *.c *.o
.a
’,
‘.c
’, or
‘.o
’), and if the
nonomatch
shell variable is set a pattern (or list of
patterns) which matches nothing is left unchanged rather than causing an
error.
The globstar
shell variable can be set to
allow ‘**
’ or
‘***
’ as a file glob pattern that
matches any string of characters including
‘/
’, recursively traversing any
existing sub-directories. For example,
ls **.c
ls
/usr/include/**/time.h
time.h
’ in the
/usr/include directory tree;
ls /usr/include/**time.h
time.h
’; and
ls
/usr/include/**time**.h
time
’ either
in a subdirectory name or in the filename itself. To prevent problems with
recursion, the ‘**
’ glob-pattern will
not descend into a symbolic link containing a directory. To override this, use
‘***
’ (+)
The noglob
shell variable can be set to
prevent filename substitution, and the expand-glob
editor command, normally bound to ^X-*
, can be used
to interactively expand individual filename substitutions.
Directory stack substitution (+)
The directory stack is a list of directories, numbered from zero,
used by the pushd
, popd
, and
dirs
builtin commands. dirs
can print, store in a file, restore and clear the directory stack at any
time, and the savedirs
and
dirsfile
shell variables can be set to store the
directory stack automatically on logout and restore it on login. The
dirstack
shell variable can be examined to see the
directory stack and set to put arbitrary directories into the directory
stack.
The character ‘=
’ followed
by one or more digits expands to an entry in the directory stack. The
special case ‘=-
’ expands to the last
directory in the stack. For example,
> dirs -v 0 /usr/bin 1 /usr/spool/uucp 2 /usr/accts/sys > echo =1 /usr/spool/uucp > echo =0/calendar /usr/bin/calendar > echo =- /usr/accts/sys
The noglob
and
nonomatch
shell variables and the
expand-glob
editor command apply to directory stack
as well as filename substitutions.
Other substitutions (+)
There are several more transformations involving filenames, not
strictly related to the above but mentioned here for completeness.
Any filename
may be expanded to a full path when the symlinks
variable is set to ‘expand
’. Quoting
prevents this expansion, and the normalize-path
editor command does it on demand. The
normalize-command
editor command expands commands in
PATH
into full paths on demand. Finally,
cd
and pushd
interpret
‘-
’ as the old working directory
(equivalent to the shell variable owd
). This is not
a substitution at all, but an abbreviation recognized by only those
commands. Nonetheless, it too can be prevented by quoting.
Commands
The next three sections describe how the shell executes commands and deals with their input and output.
Simple commands, pipelines and sequences
A simple command is a sequence of words, the first of which
specifies the command to be executed. A series of simple commands joined by
‘|
’ characters forms a pipeline. The
output of each command in a pipeline is connected to the input of the
next.
Simple commands and pipelines may be joined into sequences with
‘;
’, and will be executed
sequentially. Commands and pipelines can also be joined into sequences with
‘||
’ or
‘&&
’, indicating, as in the C
language, that the second is to be executed only if the first fails or
succeeds respectively.
A simple command, pipeline or sequence may be placed in
parentheses (‘(
’ and
‘)
’) to form a simple command, which
may in turn be a component of a pipeline or sequence. A command, pipeline or
sequence can be executed without waiting for it to terminate by following it
with an ‘&
’.
Builtin and non-builtin command execution
Builtin commands are executed within the shell. If any component of a pipeline except the last is a builtin command, the pipeline is executed in a subshell.
Parenthesized commands are always executed in a subshell.
(cd; pwd); pwd
thus prints the home
directory, leaving
you where you were (printing this after the home directory), while
cd; pwd
leaves you in the home
directory.
Parenthesized commands are most often used to prevent
cd
from affecting the current shell.
When a command to be executed is found not to be a builtin command
the shell attempts to execute the command via
execve(2). Each word in the
variable path
names a directory in which the shell
will look for the command. If the shell is not given a
-f
option, the shell hashes the names in these
directories into an internal table so that it will try an
execve(2) in only a directory
where there is a possibility that the command resides there. This greatly
speeds command location when a large number of directories are present in
the search path. This hashing mechanism is not used:
- If hashing is turned explicitly off via
unhash
. - If the shell was given a
-f
argument. - For each directory component of
path
which does not begin with a ‘/
’. - If the command contains a ‘
/
’.
In the above four cases the shell concatenates each component of the path vector with the given command name to form a path name of a file which it then attempts to execute it. If execution is successful, the search stops.
If the file has execute permissions but is not an executable to
the system (i.e., it is neither an executable binary nor a script that
specifies its interpreter), then it is assumed to be a file containing shell
commands and a new shell is spawned to read it. The
shell
special alias may be set to specify an
interpreter other than the shell itself.
On systems which do not understand the
‘#!
’ script interpreter convention the
shell may be compiled to emulate it; see the version
shell variable. If so, the shell checks the first line of the file to see if
it is of the form
#!interpreter
arg ...
Input/output
The standard input and standard output of a command may be redirected with the following syntax:
<
name- Open file name (which is first variable, command and filename expanded) as the standard input.
<<
word- Read the shell input up to a line which is identical to
word. word is not subjected to
variable, filename or command substitution, and each input line is
compared to word before any substitutions are done
on this input line. Unless a quoting
‘
\
’, ‘"
’, ‘'
’, or ‘`
’ appears in word variable and command substitution is performed on the intervening lines, allowing ‘\
’ to quote ‘$
’, ‘\
’, and ‘`
’. Commands which are substituted have all blanks, tabs, and newlines preserved, except for the final newline which is dropped. The resultant text is placed in an anonymous temporary file which is given to the command as standard input. >
name>!
name>&
name>&!
name- The file name is used as standard output. If the
file does not exist then it is created; if the file exists, it is
truncated, its previous contents being lost.
If the shell variable
noclobber
is set, then the file must not exist or be a character special file (e.g., a terminal or /dev/null) or an error results. This helps prevent accidental destruction of files. In this case the ‘!
’ forms can be used to suppress this check. If ‘notempty
’ is given innoclobber
, ‘>
’ is allowed on empty files; if ‘ask
’ is given innoclobber
, an interactive confirmation is presented, rather than an error.The forms involving ‘
&
’ route the diagnostic output into the specified file as well as the standard output. name is expanded in the same way as ‘<
’ input filenames are. >>
name>>&
name>>!
name>>&!
name- Like ‘
>
’, but appends output to the end of name. If the shell variablenoclobber
is set, then it is an error for the file not to exist, unless one of the ‘!
’ forms is given.
A command receives the environment in which the shell was invoked
as modified by the input-output parameters and the presence of the command
in a pipeline. Thus, unlike some previous shells, commands run from a file
of shell commands have no access to the text of the commands by default;
rather they receive the original standard input of the shell. The
‘<<
’ mechanism should be used to
present inline data. This permits shell command scripts to function as
components of pipelines and allows the shell to block read its input. Note
that the default standard input for a command run detached is
not the empty file /dev/null, but
the original standard input of the shell. If this is a terminal and if the
process attempts to read from the terminal, then the process will block and
the user will be notified (see Jobs).
Diagnostic output may be directed through a pipe with the standard
output. Simply use the form ‘|&
’
rather than just ‘|
’.
The shell cannot presently redirect diagnostic output without also redirecting standard output, but
( command
>
output-file )
>&
error-file
Features
Having described how the shell accepts, parses and executes command lines, we now turn to a variety of its useful features.
Control flow
The shell contains a number of commands which can be used to regulate the flow of control in command files (shell scripts) and (in limited but useful ways) from terminal input. These commands all operate by forcing the shell to reread or skip in its input and, due to the implementation, restrict the placement of some of the commands.
The foreach
,
switch
, and while
statements, as well as the if ... then ... else
form
of the if
statement, require that the major keywords
appear in a single simple command on an input line as shown below.
If the shell's input is not seekable, the shell buffers up input
whenever a loop is being read and performs seeks in this internal buffer to
accomplish the rereading implied by the loop. (To the extent that this
allows, backward goto
s will succeed on non-seekable
inputs.)
Expressions
The if
, while
, and
exit
builtin commands use expressions with a common
syntax. The expressions can include any of the operators described in the
next three sections. Note that the @
builtin command
has its own separate syntax.
Logical, arithmetical and comparison operators
These operators are similar to those of C and have the same precedence.
The operators, in descending precedence, with equivalent precedence per line, are:
( |
) |
||
~ |
|||
! |
|||
* |
/ |
% |
|
+ |
- |
||
<< |
>> |
||
<= |
>= |
< |
> |
== |
!= |
=~ |
!~ |
& |
|||
^ |
|||
| |
|||
&& |
|||
|| |
The ‘==
’
‘!=
’
‘=~
’ and
‘!~
’ operators compare their arguments
as strings; all others operate on numbers. The operators
‘=~
’ and
‘!~
’ are like
‘==
’ and
‘!=
’ except that the right hand side
is a glob-pattern (see Filename
substitution) against which the left hand operand is matched. This
reduces the need for use of the switch
builtin
command in shell scripts when all that is really needed is pattern
matching.
Null or missing arguments are considered
‘0
’. The results of all expressions
are strings, which represent decimal numbers. It is important to note that
no two components of an expression can appear in the same word; except when
adjacent to components of expressions which are syntactically significant to
the parser (‘&
’,
‘|
’,
‘<
’,
‘>
’,
‘(
’,
‘)
’) they should be surrounded by
spaces.
Command exit status
Commands can be executed in expressions and their exit status
returned by enclosing them in braces
(‘{
’ and
‘}
’). Remember that the braces should
be separated from the words of the command by spaces. Command executions
succeed, returning true, i.e., ‘1
’, if
the command exits with status 0, otherwise they fail, returning false, i.e.,
‘0
’. If more detailed status
information is required then the command should be executed outside of an
expression and the status
shell variable
examined.
File inquiry operators
Some of these operators perform true/false tests on files and
related objects. They are of the form
-
op file, where
-
op is one of:
-op
- True/false file inquiry operator
-r
- Read access.
-w
- Write access.
-x
- Execute access.
-X
- Executable in the path or shell builtin, e.g., ‘
-X ls
’ and ‘-X ls-F
’ are generally true, but ‘-X /bin/ls
’ is not. (+) -e
- Existence.
-o
- Ownership.
-z
- Zero size.
-s
- Non-zero size. (+)
-f
- Plain file.
-d
- Directory.
-l
- Symbolic link. (+) *
-b
- Block special file. (+)
-c
- Character special file. (+)
-p
- Named pipe (fifo). (+) *
-S
- Socket special file. (+) *
-u
- Set-user-ID bit is set. (+)
-g
- Set-group-ID bit is set. (+)
-k
- Sticky bit is set. (+)
-t
- file (which must be a digit) is an open file descriptor for a terminal device. (+)
-R
- Has been migrated (Convex only). (+)
-L
- Applies subsequent operators in a multiple-operator test to a symbolic link rather than to the file to which the link points. (+) *
file is command and filename expanded and
then tested to see if it has the specified relationship to the real user. If
file does not exist or is inaccessible or, for the
operators indicated by ‘*’, if the specified file type does
not exist on the current system, then all inquiries return false, i.e.,
‘0
’.
These operators may be combined for conciseness:
-
xy
file
-
x
file &&
-
y file
-fx
’ is true (returns
‘1
’) for plain executable files, but not
for directories.
-L
may be used in a multiple-operator test
to apply subsequent operators to a symbolic link rather than to the file to
which the link points. For example, -lLo
is true for
links owned by the invoking user. -Lr
,
-Lw
, and -Lx
are always true
for links and false for non-links. -L
has a
different meaning when it is the last operator in a multiple-operator test;
see below.
It is possible but not useful, and sometimes misleading, to
combine operators which expect file to be a file with
operators which do not (e.g., -X
and
-t
). Following -L
with a
non-file operator can lead to particularly strange results.
Other operators return other information, i.e., not just
‘0
’ or
‘1
’. (+) They have the same format as
before; -
op may be one of:
-op
- Extended file inquiry operator
-A
- Last file access time, as the number of seconds since the epoch.
-A:
- Like ‘
A
’, but in timestamp format, e.g., ‘Fri May 14 16:36:10 1993’. -M
- Last file modification time.
-M:
- Like
-M
, but in timestamp format. -C
- Last inode modification time.
-C:
- Like
-C
, but in timestamp format. -D
- Device number.
-I
- Inode number.
-F
- Composite
-f
ile identifier, in the form device:inode. -L
- The name of the file pointed to by a symbolic link.
-N
- Number of (hard) links.
-P
- Permissions, in octal, without leading zero.
-P:
- Like
-P
, with leading zero. -P
mode- Equivalent to
For example, ‘
-P
file&
mode-P22 file
’ returns ‘22’ if file is writable by group and other, ‘20’ if by group only, and ‘0’ if by neither. -P
mode:
- Like
-P
mode, with leading zero. -U
- Numeric userid.
-U:
- Username, or the numeric userid if the username is unknown.
-G
- Numeric groupid.
-G:
- Groupname, or the numeric groupid if the groupname is unknown.
-Z
- Size, in bytes.
Only one of these operators may appear in a multiple-operator
test, and it must be the last. Note that
‘L
’ has a different meaning at the end
of and elsewhere in a multiple-operator test. Because ‘0’ is a
valid return value for many of these operators, they do not return
‘0’ when they fail: most return ‘-1’, and
‘F
’ returns
‘:
’.
If the shell is compiled with POSIX defined (see the
version
shell variable), the result of a file
inquiry is based on the permission bits of the file and not on the result of
the access(2) system call. For
example, if one tests a file with -w
whose
permissions would ordinarily allow writing but which is on a file system
mounted read-only, the test will succeed in a POSIX shell but fail in a
non-POSIX shell.
File inquiry operators can also be evaluated with the
filetest
builtin command (+).
Jobs
The shell associates a job with each
pipeline. It keeps a table of current jobs, printed by the
jobs
command, and assigns them small integer
numbers. When a job is started asynchronously with
‘&
’, the shell prints a line which
looks like
[1] 1234
indicating that the job which was started asynchronously was job number 1 and had one (top-level) process, whose process id was 1234.
If you are running a job and wish to do something else you may hit
the suspend key (usually ^Z
), which sends a STOP
signal to the current job. The shell will then normally indicate that the
job has been
Suspended
listjobs
shell variable
is set, all jobs will be listed like the jobs
builtin
command; if it is set to ‘long
’ the
listing will be in long format, like ‘jobs
-l
’. You can then manipulate the state of the suspended job. You
can put it in the “background” with the
bg
command or run some other commands and eventually
bring the job back into the “foreground” with
fg
. (See also the
run-fg-editor
editor command.) A
^Z
takes effect immediately and is like an interrupt
in that pending output and unread input are discarded when it is typed. The
wait
builtin command causes the shell to wait for all
background jobs to complete.
The ^]
key sends a delayed suspend signal,
which does not generate a STOP signal until a program attempts to
read(2) it, to the current job. This
can usefully be typed ahead when you have prepared some commands for a job
which you wish to stop after it has read them. The
^Y
key performs this function in
csh(1); in
tcsh
, ^Y
is an editing
command. (+)
A job being run in the background stops if it tries to read from the terminal. Background jobs are normally allowed to produce output, but this can be disabled by giving the command
stty tostop
There are several ways to refer to jobs in the shell. The
character ‘%
’ introduces a job name.
If you wish to refer to job number 1, you can name it as
%1
%1
fg %1
%1 &
bg %1
%ex
ex
’. It is also possible to type
%?string
The shell maintains a notion of the current and previous jobs. In
output pertaining to jobs, the current job is marked with a
‘+
’ and the previous job with a
‘-
’. The abbreviations
‘%+
’,
‘%
’, and (by analogy with the syntax
of the history
mechanism)
‘%%
’ all refer to the current job, and
‘%-
’ refers to the previous job.
The job control mechanism requires that the
stty(1) option
‘new
’ be set on some systems. It is an
artifact from a “new” implementation of the tty driver which
allows generation of interrupt characters from the keyboard to tell jobs to
stop. See stty(1) and the
setty
builtin command for details on setting options
in the new tty driver.
Status reporting
The shell learns immediately whenever a process changes state. It
normally informs you whenever a job becomes blocked so that no further
progress is possible, but only right before it prints a prompt. This is done
so that it does not otherwise disturb your work. If, however, you set the
shell variable notify
, the shell will notify you
immediately of changes of status in background jobs. There is also a builtin
command notify
which marks a single process so that
its status changes will be immediately reported. By default
notify
marks the current process; simply enter
notify
When you try to leave the shell while jobs are stopped, you will be warned that
There are suspended
jobs.
You may use the jobs
command to see what
they are. If you do this or immediately try to exit again, the shell will
not warn you a second time, and the suspended jobs will be terminated.
Automatic, periodic and timed events (+)
There are various ways to run commands and take other actions automatically at various times in the “life cycle” of the shell. They are summarized here, and described in detail under the appropriate Builtin commands, Special shell variables, and Special aliases (+).
The sched
builtin command puts commands in
a scheduled-event list, to be executed by the shell at a given time.
The beepcmd
,
cwdcmd
, jobcmd
,
periodic
, precmd
, and
postcmd
Special aliases (+) can be
set, respectively, to execute commands: when the shell wants to ring the
bell, when the working directory changes, when a job is started or is
brought into the foreground, every tperiod
minutes,
before each prompt, and before each command gets executed.
The autologout
shell variable can be set
to log out or lock the shell after a given number of minutes of
inactivity.
The mail
shell variable can be set to
check for new mail periodically.
The printexitvalue
shell variable can be
set to print the exit status of commands which exit with a status other than
zero.
The rmstar
shell variable can be set to
ask the user, when
rm *
The time
shell variable can be set to
execute the time
builtin command after the
completion of any process that takes more than a given number of CPU
seconds.
The watch
and who
shell variables can be set to report when selected users log in or out, and
the log
builtin command reports on those users at
any time.
Native Language System support (+)
The shell is eight bit clean (if so compiled; see the
version
shell variable) and thus supports character
sets needing this capability. NLS support differs depending on whether or
not the shell was compiled to use the system's NLS (again, see
version
). In either case, 7-bit ASCII is the default
character code (e.g., the classification of which characters are printable)
and sorting, and changing the LANG
or
LC_CTYPE
environment variables causes a check for
possible changes in these respects.
When using the system's NLS, the
setlocale(3) function is called
to determine appropriate character code/classification and sorting (e.g.,
‘en_CA.UTF-8’ would yield ‘UTF-8’ as the
character code). This function typically examines the
LANG
and LC_CTYPE
environment variables; refer to the system documentation for further
details. When not using the system's NLS, the shell simulates it by assuming
that the ISO 8859-1 character set is used whenever either of the
LANG
and LC_CTYPE
variables
are set, regardless of their values. Sorting is not affected for the
simulated NLS.
In addition, with both real and simulated NLS, all printable
characters in the range \200-\377, i.e., those that have
M-
char bindings, are
automatically rebound to self-insert-command
. The
corresponding binding for the
escape-char sequence, if any,
is left alone. These characters are not rebound if the
NOREBIND
environment variable is set. This may be
useful for the simulated NLS or a primitive real NLS which assumes full ISO
8859-1. Otherwise, all M-
char
bindings in the range \240-\377 are effectively undone. Explicitly rebinding
the relevant keys with bindkey
is of course still
possible.
Unknown characters (i.e., those that are neither printable nor control characters) are printed in the format \nnn. If the tty is not in 8 bit mode, other 8 bit characters are printed by converting them to ASCII and using standout mode. The shell never changes the 7/8 bit mode of the tty and tracks user-initiated changes of 7/8 bit mode. NLS users (or, for that matter, those who want to use a meta key) may need to explicitly set the tty in 8 bit mode through the appropriate stty(1) command in, e.g., the ~/.login file.
OS variant support (+)
A number of new builtin commands are provided to support features in particular operating systems. All are described in detail in the Builtin commands section.
On systems that support TCF (aix-ibm370, aix-ps2),
getspath
and setspath
get
and set the system execution path, getxvers
and
setxvers
get and set the experimental version prefix
and migrate
migrates processes between sites. The
jobs
builtin prints the site on which each job is
executing.
Under BS2000, bs2cmd
executes commands of
the underlying BS2000/OSD operating system.
Under Domain/OS, inlib
adds shared
libraries to the current environment, rootnode
changes the rootnode and ver
changes the
systype.
Under Mach, setpath
is equivalent to
Mach's setpath(1).
Under Masscomp/RTU and Harris CX/UX,
universe
sets the universe.
Under Harris CX/UX, ucb
or
att
runs a command under the specified universe.
Under Convex/OS, warp
prints or sets the
universe.
The VENDOR
,
OSTYPE
, and MACHTYPE
environment variables indicate respectively the vendor, operating system and
machine type (microprocessor class or machine model) of the system on which
the shell thinks it is running. These are particularly useful when sharing
one's home directory between several types of machines; one can, for
example,
set path = (~/bin.$MACHTYPE /usr/ucb /bin /usr/bin .)
in one's ~/.login and put executables compiled for each machine in the appropriate directory.
The version
shell variable indicates what
options were chosen when the shell was compiled.
Note also the newgrp
builtin, the
afsuser
and echo_style
shell
variables and the system-dependent locations of the shell's input files (see
FILES).
Signal handling
Login shells ignore interrupts when reading the file
~/.logout. The shell ignores quit signals unless
started with -q
. Login shells catch the terminate
signal, but non-login shells inherit the terminate behavior from their
parents. Other signals have the values which the shell inherited from its
parent.
In shell scripts, the shell's handling of interrupt and terminate
signals can be controlled with onintr
, and its
handling of hangups can be controlled with hup
and
nohup
.
The shell exits on a hangup (see also the
logout
shell variable). By default, the shell's
children do too, but the shell does not send them a hangup when it exits.
hup
arranges for the shell to send a hangup to a
child when it exits, and nohup
sets a child to
ignore hangups.
Terminal management (+)
The shell uses three different sets of terminal
(“tty”) modes: ‘edit’, used when editing;
‘quote’, used when quoting literal characters; and
‘execute’, used when executing commands. The shell holds some
settings in each mode constant, so commands which leave the tty in a
confused state do not interfere with the shell. The shell also matches
changes in the speed and padding of the tty. The list of tty modes that are
kept constant can be examined and modified with the
setty
builtin. Note that although the editor uses
CBREAK mode (or its equivalent), it takes typed-ahead characters anyway.
The echotc
, settc
,
and telltc
commands can be used to manipulate and
debug terminal capabilities from the command line.
On systems that support SIGWINCH or SIGWINDOW, the shell adapts to
window resizing automatically and adjusts the environment variables
LINES
and COLUMNS
if set. If
the environment variable TERMCAP
contains
‘li#
’ and
‘co#
’ fields, the shell adjusts them
to reflect the new window size.
REFERENCE
The next sections of this manual describe all of the available Builtin commands, Special aliases (+), and Special shell variables.
Builtin commands
%
job- A synonym for the
fg
builtin command. %
job&
- A synonym for the
bg
builtin command. :
- Does nothing, successfully.
@
@
name=
expr@
name[
index] =
expr@
name++|--
@
name[
index]++|--
- The first form prints the values of all shell variables.
The second form assigns the value of expr to name.
The third form assigns the value of expr to the index'th component of name; both name and its index'th component must already exist.
expr may contain the operators ‘
*
’, ‘+
’, etc., as in C. If expr contains ‘<
’, ‘>
’, ‘&
’, or ‘|
’ then at least that part of expr must be placed within (‘’ and ‘
’). Note that the syntax of expr has nothing to do with that described under Expressions.
The fourth and fifth forms increment (‘
++
’) or decrement (‘--
’) name or its index'th component.The space between ‘
@
’ and name is required. The spaces between name and ‘=
’ and between ‘=
’ and expr are optional. Components of expr must be separated by spaces.
alias
[name [wordlist]]- Without arguments, prints all aliases.
With name, prints the alias for name.
With name and wordlist, assigns wordlist as the alias of name. wordlist is command and filename substituted.
name may not be ‘
alias
’ or ‘unalias
’. See also theunalias
builtin command. alloc
- Shows the amount of dynamic memory acquired, broken down into used and free memory. With an argument shows the number of free and used blocks in each size category. The categories start at size 8 and double at each step. This command's output may vary across system types, because systems other than the VAX may use a different memory allocator.
bg
[%
job ...]- Puts the specified jobs (or, without arguments, the current job) into the
background, continuing each if it is stopped. job
may be a number, a string, ‘
’, ‘
%
’, ‘+
’, or ‘-
’ as described under Jobs.
bindkey
[-l
|-d
|-e
|-v
|-u
] (+)bindkey
[-a
] [-b
] [-k
] [-r
] [--
] key (+)bindkey
[-a
] [-b
] [-k
] [-c
|-s
] [--
] key command (+)- The first form either lists all bound keys and the editor command to which
each is bound, lists a description of the commands, or binds all keys to a
specific mode.
The second form lists the editor command to which key is bound.
The third form binds the editor command command to key.
Supported
bindkey
options:- Option
bindkey
description-a
- Lists or changes key-bindings in the alternative key map. This is the
key map used in
vimode
command mode. -b
- key is interpreted as a control character
written
^
character (e.g.,^A
) orC-
character (e.g.,C-A
), a meta character writtenM-
character (e.g.,M-A
), a function key writtenF-
string (e.g.,F-string
), or an extended prefix key writtenX-
character (e.g.,X-A
). -c
- command is interpreted as a builtin or external command instead of an editor command.
-d
- Binds all keys to the standard bindings for the default editor, as per
-e
and-v
. -e
- Binds all keys to
emacs(1)-style bindings.
Unsets
vimode
. -k
- key is interpreted as a symbolic arrow key name, which may be one of ‘down’, ‘up’, ‘left’, or ‘right’.
-l
- Lists all editor commands and a short description of each.
-r
- Removes key's binding. Be careful:
‘
bindkey -r
’ does not bind key toself-insert-command
, it unbinds key completely. -s
- command is taken as a literal string and treated as terminal input when key is typed. Bound keys in command are themselves reinterpreted, and this continues for ten levels of interpretation.
-u
(or any invalid option)- Prints a usage message.
-v
- Binds all keys to vi(1)-style
bindings. Sets
vimode
. --
- Forces a break from option processing, so the next word is taken as
key even if it begins with
‘
-
’.
key may be a single character or a string. If a command is bound to a string, the first character of the string is bound to
sequence-lead-in
and the entire string is bound to the command.Control characters in key can be literal (they can be typed by preceding them with the editor command
quoted-insert
, normally bound to^V
) or written caret-character style, e.g.,^A
. Delete is written^?
(caret-question mark). key and command can contain backslashed escape sequences (in the style of System V echo(1)) as follows:- Escape
- Description
\a
- Bell.
\b
- Backspace.
\e
- Escape.
\f
- Form feed.
\n
- Newline.
\r
- Carriage return.
\t
- Horizontal tab.
\v
- Vertical tab.
\
nnn- The ASCII character corresponding to the octal number nnn.
‘
\
’ nullifies the special meaning of the following character, if it has any, notably ‘\
’ and ‘^
’.
bs2cmd
bs2000-command (+)- Passes bs2000-command to the BS2000 command interpreter for execution. Only non-interactive commands can be executed, and it is not possible to execute any command that would overlay the image of the current process, like /EXECUTE or /CALL-PROCEDURE. (BS2000 only)
break
- Causes execution to resume after the
end
of the nearest enclosingforeach
orwhile
. The remaining commands on the current line are executed. Multi-level breaks are thus possible by writing them all on one line. breaksw
- Causes a break from a
switch
, resuming after theendsw
. builtins
(+)- Prints the names of all builtin commands.
bye
(+)- A synonym for the
logout
builtin command. Available only if the shell was so compiled; see theversion
shell variable. case
label:
- A label in a
switch
statement as discussed below. cd
[-p
] [-l
] [-n
|-v
] [--
] [name]- If a directory name is given, changes the shell's
working directory to name. If not, changes to
home
, unless thecdtohome
variable is not set, in which case a name is required. If name is ‘-
’ it is interpreted as the previous working directory (see Other substitutions (+)). (+) If name is not a subdirectory of the current directory (and does not begin with ‘/
’, ‘./
’ or ‘../
’), each component of the variablecdpath
is checked to see if it has a subdirectory name. Finally, if all else fails but name is a shell variable whose value begins with ‘/
’ or ‘.
’, then this is tried to see if it is a directory, and the-p
option is implied.With
-p
, prints the final directory stack, just likedirs
. The-l
,-n
, and-v
flags have the same effect oncd
as ondirs
, and they imply-p
(+). Using--
forces a break from option processing so the next word is taken as the directory name even if it begins with ‘-
’ (+).See also the
implicitcd
andcdtohome
shell variables. chdir
- A synonym for the
cd
builtin command. complete
[command [word/
pattern/
list[:
select]/
[[suffix]/
] ...]] (+)- Without arguments, lists all completions.
With command, lists completions for command.
With command and word ..., defines completions.
command may be a full command name or a glob-pattern (see Filename substitution). It can begin with ‘
-
’ to indicate that completion should be used only whencommand
is ambiguous.word specifies which word relative to the current word is to be completed, and may be one of the following:
- word
- Completion word
c
- Current-word completion. pattern is a glob-pattern which must match the beginning of the current word on the command line. pattern is ignored when completing the current word.
C
- Like ‘
c
’, but includes pattern when completing the current word. n
- Next-word completion. pattern is a glob-pattern which must match the beginning of the previous word on the command line.
N
- Like ‘
n
’, but must match the beginning of the word two before the current word. p
- Position-dependent completion. pattern is a numeric range, with the same syntax used to index shell variables, which must include the current word.
list, the list of possible completions, may be one of the following:
- list
- Completion item
a
- Aliases.
b
- Bindings (editor commands).
c
- Commands (builtin or external commands).
C
- External commands which begin with the supplied path prefix.
d
- Directories.
D
- Directories which begin with the supplied path prefix.
e
- Environment variables.
f
- Filenames.
F
- Filenames which begin with the supplied path prefix.
g
- Groupnames.
j
- Jobs.
l
- Limits.
n
- Nothing.
s
- Shell variables.
S
- Signals.
t
- Plain (“text”) files.
T
- Plain (“text”) files which begin with the supplied path prefix.
v
- Any variables.
u
- Usernames.
x
- Like ‘
n
’, but prints select whenlist-choices
is used. X
- Completions.
$
var- Words from the variable var.
(...)
- Words from the given list.
`...`
- Words from the output of command.
select is an optional glob-pattern. If given, words from only list that match select are considered and the
fignore
shell variable is ignored. The list types ‘$var
’, ‘(...)
’, and ‘`...`
’ may not have a select pattern, and ‘x
’ uses select as an explanatory message when thelist-choices
editor command is used.suffix is a single character to be appended to a successful completion. If null, no character is appended. If omitted (in which case the fourth delimiter can also be omitted), a slash is appended to directories and a space to other words.
command invoked from list ‘
`...`
’ has the additional environment variableCOMMAND_LINE
set, which contains (as its name indicates) contents of the current (already typed in) command line. One can examine and use contents of theCOMMAND_LINE
environment variable in a custom script to build more sophisticated completions (see completion for svn(1) included in this package).Now for some examples. Some commands take only directories as arguments, so there's no point completing plain files.
> complete cd 'p/1/d/'
completes only the first word following ‘
cd
’ (‘p/1
’) with a directory. ‘p
’-type completion can also be used to narrow down command completion:> co[^D] complete compress > complete -co* 'p/0/(compress)/' > co[^D] > compress
This completion completes commands (words in position 0, ‘
p/0
’) which begin with ‘co
’ (thus matching ‘co*
’) to ‘compress
’ (the only word in the list). The leading ‘-
’ indicates that this completion is to be used with only ambiguous commands.> complete find 'n/-user/u/'
is an example of ‘
n
’-type completion. Any word following ‘find
’ and immediately following ‘-user
’ is completed from the list of users.> complete cc 'c/-I/d/'
demonstrates ‘
c
’-type completion. Any word following ‘cc
’ and beginning with ‘-I
’ is completed as a directory. ‘-I
’ is not taken as part of the directory because we used lowercase ‘c
’.Different lists are useful with different commands.
> complete alias 'p/1/a/' > complete man 'p/*/c/' > complete set 'p/1/s/' > complete true 'p/1/x:Truth has no options./'
These complete words following ‘
alias
’ with aliases, ‘man
’ with commands, and ‘set
’ with shell variables.true
doesn't have any options, so ‘x
’ does nothing when completion is attempted and printswhen completion choices are listed.Truth has no options.
Note that the ‘
man
’ example, and several other examples below, could just as well have used ‘'c/*'
’ or ‘'n/*'
’ as ‘'p/*'
’.Words can be completed from a variable evaluated at completion time,
> complete ftp 'p/1/$hostnames/' > set hostnames = (rtfm.mit.edu tesla.ee.cornell.edu) > ftp [^D] rtfm.mit.edu tesla.ee.cornell.edu > ftp [^C] > set hostnames = (rtfm.mit.edu tesla.ee.cornell.edu uunet.uu.net) > ftp [^D] rtfm.mit.edu tesla.ee.cornell.edu uunet.uu.net
or from a command run at completion time:
> complete kill 'p/*/`ps | awk \{print\ \$1\}`/' > kill -9 [^D] 23113 23377 23380 23406 23429 23529 23530 PID
Note that the
complete
command does not itself quote its arguments, so the braces, space and ‘$
’ in ‘{print $1}
’ must be quoted explicitly.One command can have multiple completions:
> complete dbx 'p/2/(core)/' 'p/*/c/'
completes the second argument to ‘
dbx
’ with the word ‘core
’ and all other arguments with commands. Note that the positional completion is specified before the next-word completion. Because completions are evaluated from left to right, if the next-word completion were specified first it would always match and the positional completion would never be executed. This is a common mistake when defining a completion.The select pattern is useful when a command takes files with only particular forms as arguments. For example,
> complete cc 'p/*/f:*.[cao]/'
completes ‘
cc
’ arguments to files ending in only ‘.c
’, ‘.a
’, or ‘.o
’. select can also exclude files, using negation of a glob-pattern as described under Filename substitution. One might use> complete rm 'p/*/f:^*.{c,h,cc,C,tex,1,man,l,y}/'
to exclude precious source code from ‘
rm
’ completion. Of course, one could still type excluded names manually or override the completion mechanism using thecomplete-word-raw
orlist-choices-raw
editor commands.The ‘
C
’, ‘D
’, ‘F
’, and ‘T
’ lists are like ‘c
’, ‘d
’, ‘f
’, and ‘t
’ respectively, but they use the select argument in a different way: to restrict completion to files beginning with a particular path prefix. For example, the Elm mail program uses ‘=
’ as an abbreviation for one's mail directory. One might use> complete elm c@=@F:$HOME/Mail/@
to complete
as if it wereelm -f =
Note that we used the separator ‘elm -f ~/Mail/
@
’ instead of ‘/
’ to avoid confusion with the select argument, and we used ‘$HOME
’ instead of ‘~
’ because home directory substitution works at only the beginning of a word.suffix is used to add a nonstandard suffix (not space or ‘
/
’ for directories) to completed words.> complete finger 'c/*@/$hostnames/' 'p/1/u/@'
completes arguments to ‘
finger
’ from the list of users, appends an ‘@
’, and then completes after the ‘@
’ from the ‘hostnames
’ variable. Note again the order in which the completions are specified.Finally, here's a complex example for inspiration:
> complete find \ 'n/-name/f/' 'n/-newer/f/' 'n/-{,n}cpio/f/' \ ´n/-exec/c/' 'n/-ok/c/' 'n/-user/u/' \ 'n/-group/g/' 'n/-fstype/(nfs 4.2)/' \ 'n/-type/(b c d f l p s)/' \ ´c/-/(name newer cpio ncpio exec ok user \ group fstype type atime ctime depth inum \ ls mtime nogroup nouser perm print prune \ size xdev)/' \ 'p/*/d/'
This completes words following ‘
-name
’, ‘-newer
’, ‘-cpio
’, or ‘-ncpio
’ (note the pattern which matches both) to files, words following ‘-exec
’ or ‘-ok
’ to commands, words following ‘-user
’ and ‘-group
’ to users and groups respectively and words following ‘-fstype
’ or ‘-type
’ to members of the given lists. It also completes the switches themselves from the given list (note the use of ‘c
’-type completion) and completes anything not otherwise completed to a directory. Whew.Remember that programmed completions are ignored if the word being completed is a tilde substitution (beginning with ‘
~
’) or a variable (beginning with ‘$
’). See also theuncomplete
builtin command. continue
- Continues execution of the nearest enclosing
while
orforeach
. The rest of the commands on the current line are executed. default:
- Labels the default case in a
switch
statement. It should come after allcase
labels.
dirs
[-l
] [-n
|-v
]dirs
-S
|-L
[filename] (+)dirs
-c
(+)- The first form prints the directory stack. The top of the stack is at the
left and the first directory in the stack is the current directory. With
-l
, ‘~
’ or ‘~name
’ in the output is expanded explicitly tohome
or the pathname of the home directory for user name. (+) With-n
, entries are wrapped before they reach the edge of the screen. (+) With-v
, entries are printed one per line, preceded by their stack positions. (+) If more than one of-n
or-v
is given,-v
takes precedence.-p
is accepted but does nothing.The second form with
-S
saves the directory stack to filename as a series ofcd
andpushd
commands. The second form with-L
sources filename, which is presumably a directory stack file saved by the-S
option or thesavedirs
mechanism. In either case,dirsfile
is used if filename is not given and ~/.cshdirs is used ifdirsfile
is unset.Note that login shells do the equivalent of
on startup and, ifdirs -L
savedirs
is set,before exiting. Because only ~/.tcshrc is normally sourced before ~/.cshdirs,dirs -S
dirsfile
should be set in ~/.tcshrc rather than ~/.login.The third form clears the directory stack.
echo
[-n
] word ...- Writes each word to the shell's standard output,
separated by spaces and terminated with a newline. The
echo_style
shell variable may be set to emulate (or not) the flags and escape sequences of the BSD and/or System V versions of echo(1); see Escape sequences (+) and echo(1). echotc
[-sv
] arg ... (+)- Exercises the terminal capabilities (see
termcap(5)) in
arg. For example,
sends the cursor to the home position,
echotc home
sends it to column 3 and row 10, andechotc cm 3 10
printsechotc ts 0; echo "This is a test."; echotc fs
in the status line.This is a test.
If arg is ‘
baud
’, ‘cols
’, ‘lines
’, ‘meta
’, or ‘tabs
’, prints the value of that capability (“yes” or “no” indicating that the terminal does or does not have that capability). One might use this to make the output from a shell script less verbose on slow terminals, or limit command output to the number of lines on the screen:> set history=`echotc lines` > @ history--
Termcap strings may contain wildcards which will not echo correctly. One should use double quotes when setting a shell variable to a terminal capability string, as in the following example that places the date in the status line:
> set tosl="`echotc ts 0`" > set frsl="`echotc fs`" > echo -n "$tosl";date; echo -n "$frsl"
With
-s
, nonexistent capabilities return the empty string rather than causing an error. With-v
, messages are verbose.
eval
arg ...- Treats the arguments as input to the shell and executes the resulting
command(s) in the context of the current shell. This is usually used to
execute commands generated as the result of command or variable
substitution, because parsing occurs before these substitutions. See
tset(1) for a sample use of
eval
. exec
command ...- Executes the specified command in place of the current shell.
exit
[expr]- The shell exits either with the value of the specified expr (an expression, as described under Expressions) or, without expr, with the value 0.
fg
[%
job ...]- Brings the specified jobs (or, without arguments, the current job) into
the foreground, continuing each if it is stopped.
job may be a number, a string,
‘
’, ‘
%
’, ‘+
’, or ‘-
’ as described under Jobs. See also therun-fg-editor
editor command. filetest -
op file ... (+)- Applies op (which is a file inquiry operator as described under File inquiry operators) to each file and returns the results as a space-separated list.
foreach
name(
wordlist)
...
end
- Successively sets the variable name to each member
of wordlist and executes the sequence of commands
between this command and the matching
end
. (Bothforeach
andend
must appear alone on separate lines.) The builtin commandcontinue
may be used to continue the loop prematurely and the builtin commandbreak
to terminate it prematurely. When this command is read from the terminal, the loop is read once prompting with(orforeach?
prompt2
) before any statements in the loop are executed. If you make a mistake typing in a loop at the terminal you can rub it out.
getspath
(+)- Prints the system execution path. (TCF only)
getxvers
(+)- Prints the experimental version prefix. (TCF only)
glob
word ...- Like
echo
, but the-n
parameter is not recognized and words are delimited by null characters in the output. Useful for programs which wish to use the shell to filename expand a list of words. goto
word- word is filename and command-substituted to yield a
string of the form ‘label’. The shell
rewinds its input as much as possible, searches for a line of the form
possibly preceded by blanks or tabs, and continues execution after that line.
label:
hashstat
- Prints a statistics line indicating how effective the internal hash table
has been at locating commands (and avoiding
exec
's). Anexec
is attempted for each component of thepath
where the hash function indicates a possible hit, and in each component which does not begin with a ‘/
’.On machines without vfork(2), prints only the number and size of hash buckets.
history
[-hTr
] [n]history
-S
|-L
|-M
[filename] (+)history
-c
(+)- The first form prints the history event list. If n
is given only the n most recent events are printed
or saved. With
-h
, the history list is printed without leading numbers. If-T
is specified, timestamps are printed also in comment form. This can be used to produce files suitable for loading withorhistory -L
source -h
With
-r
, the order of printing is most recent first rather than oldest first.The second form with
-S
saves the history list to filename. If the first word of thesavehist
shell variable is set to a number, at most that many lines are saved. If the second word ofsavehist
is set to ‘merge
’, the history list is merged with the existing history file instead of replacing it (if there is one) and sorted by time stamp. (+) Merging is intended for an environment like the X Window System with several shells in simultaneous use. If the second word ofsavehist
is ‘merge
’ and the third word is set to ‘lock
’, the history file update will be serialized with other shell sessions that would possibly like to merge history at exactly the same time.The second form with
-L
appends filename (which is presumably a history list saved by the-S
option or thesavehist
mechanism) to the history list.-M
is like-L
, but the contents of filename are merged into the history list and sorted by timestamp. In either case,histfile
is used if filename is not given and ~/.history is used ifhistfile
is unset.Note that
is exactly likehistory -L
except that it does not require a filename.source -h
Note that login shells do the equivalent of
on startup and, ifhistory -L
savehist
is set,before exiting. Because only ~/.tcshrc is normally sourced before ~/.history,history -S
histfile
should be set in ~/.tcshrc rather than ~/.login.If
histlit
is set, the first and second forms print and save the literal (unexpanded) form of the history list.The third form clears the history list.
hup
[command] (+)- With command, runs command
such that it will exit on a hangup signal and arranges for the shell to
send it a hangup signal when the shell exits. Note that commands may set
their own response to hangups, overriding
hup
. Without an argument, causes the non-interactive shell only to exit on a hangup for the remainder of the script. See also Signal handling and thenohup
builtin command. if
(
expr)
command- If expr (an expression, as described under
Expressions) evaluates true, then
command is executed. Variable substitution on
command happens early, at the same time it does for
the rest of the
if
command. command must be a simple command, not an alias, a pipeline, a command list or a parenthesized command list, but it may have arguments. Input/output redirection occurs even if expr is false and command is thus not executed; this is a bug.
if
(
expr) then
...
else if
(
expr2) then
...
else
...
endif
- If the specified expr is true then the commands to
the first
else
are executed; otherwise if expr2 is true then the commands to the secondelse
are executed, etc. Any number ofelse if
pairs are possible; only oneendif
is needed. Theelse
part is likewise optional. (The wordselse
andendif
must appear at the beginning of input lines; theif
must appear alone on its input line or after anelse
.)
inlib
shared-library ... (+)- Adds each shared-library to the current environment. There is no way to remove a shared library. (Domain/OS only)
jobs
[-l
]jobs
-Z
[title] (+)- The first form lists the active jobs. With
-l
, lists process IDs in addition to the normal information. On TCF systems, prints the site on which each job is executing.The second form with the
-Z
option sets the process title to title using setproctitle(3) where available. If no title is provided, the process title will be cleared. kill
-l
kill
[-s
signal]%
job|pid ...- The first form lists the signal names.
The second form sends the specified signal (or, if none is given, the TERM (terminate) signal) to the specified jobs or processes. job may be a number, a string, ‘
’, ‘
%
’, ‘+
’, or ‘-
’ as described under Jobs. Signals are either given by number or by name (as given in /usr/include/signal.h, stripped of the prefix ‘SIG’).There is no default job; entering just
does not send a signal to the current job. If the signal being sent is TERM (terminate) or HUP (hangup), then the job or process is sent a CONT (continue) signal as well.kill
limit
[-h
] [resource [maximum-use]]- Limits the consumption by the current process and each process it creates
to not individually exceed maximum-use on the
specified resource.
If no maximum-use is given, then the current limit for resource is printed.
If no resource is given, then all limitations are given.
If the
-h
flag is given, the hard limits are used instead of the current limits. The hard limits impose a ceiling on the values of the current limits. Only the super-user may raise the hard limits, but a user may lower or raise the current limits within the legal range.Controllable resource types currently include (if supported by the OS):
- resource
- Resource description
concurrency
- Maximum number of threads for this process.
coredumpsize
- Size of the largest core dump that will be created.
cputime
- Maximum number of cpu-seconds to be used by each process.
datasize
- Maximum growth of the data+stack region via sbrk(2) beyond the end of the program text.
descriptors
oropenfiles
- Maximum number of open files for this process.
filesize
- Largest single file which can be created.
heapsize
- Maximum amount of memory a process may allocate per brk(2) system call.
kqueues
- Maximum number of kqueues allocated for this process.
maxlocks
- Maximum number of locks for this user.
maxmessage
- Maximum number of bytes in POSIX mqueues for this user.
maxnice
- Maximum nice priority the user is allowed to raise mapped from [19...-20] to [0...39] for this user.
maxproc
- Maximum number of simultaneous processes for this user id.
maxrtprio
- Maximum realtime priority for this user.
maxrttime
- Timeout for RT tasks in microseconds for this user.
maxsignal
- Maximum number of pending signals for this user.
maxthread
- Maximum number of simultaneous threads (lightweight processes) for this user id.
memorylocked
- Maximum size which a process may lock into memory using mlock(2).
memoryuse
- Maximum amount of physical memory a process may have allocated to it at a given time.
posixlocks
- Maximum number of POSIX advisory locks for this user.
pseudoterminals
- Maximum number of pseudo-terminals for this user.
sbsize
- Maximum size of socket buffer usage for this user.
stacksize
- Maximum size of the automatically-extended stack region.
swapsize
- Maximum amount of swap space reserved or used for this user.
threads
- Maximum number of threads for this process.
vmemoryuse
- Maximum amount of virtual memory a process may have allocated to it at a given time (address space).
maximum-use may be given as a (floating point or integer) number followed by a scale factor. For all limits other than
cputime
the default scale is ‘k
’ or ‘kilobytes
’ (1024 bytes); a scale factor of ‘m
’ or ‘megabytes
’ (1048576 bytes) or ‘g
’ or ‘gigabytes
’ (1073741824 bytes) may also be used. Forcputime
the default scaling is ‘seconds
’, while ‘m
’ for minutes or ‘h
’ for hours, or a time of the form ‘mm:
ss’ giving minutes and seconds may be used.If maximum-use is ‘
unlimited
’, then the limitation on the specified resource is removed (this is equivalent to theunlimit
builtin command).For both resource names and scale factors, unambiguous prefixes of the names suffice.
log
(+)- Prints the
watch
shell variable and reports on each user indicated inwatch
who is logged in, regardless of when they last logged in. See alsowatchlog
. login
- Terminates a login shell, replacing it with an instance of /bin/login. This is one way to log off, included for compatibility with sh(1).
logout
- Terminates a login shell. Especially useful if
ignoreeof
is set. ls-F
[-
switch ...] [file ...] (+)- Lists files like
but much faster.
ls -F
ls-F
identifies each type of special file in the listing with a special character suffix:- Suffix
- Special file type
/
- Directory.
*
- Executable.
#
- Block device.
%
- Character device.
|
- Named pipe (systems with named pipes only).
=
- Socket (systems with sockets only).
@
- Symbolic link (systems with symbolic links only).
+
- Hidden directory (AIX only) or context dependent (HP/UX only).
:
- Network special (HP/UX only).
If the
listlinks
shell variable is set, symbolic links are identified in more detail (on only systems that have them, of course):- Suffix
- Symbolic link type
@
- Symbolic link to a non-directory.
>
- Symbolic link to a directory.
&
- Orphaned (broken) symbolic link.
listlinks
also slows downls-F
and causes partitions holding files pointed to by symbolic links to be mounted.If the
listflags
shell variable is set to ‘x
’, ‘a
’, or ‘A
’, or any combination thereof (e.g., ‘xA
’), they are used as flags tols-F
, making it act likels -xF ls -Fa ls -FA
or a combination, for example
ls -FxA
On machines where
is not the default,ls -C
ls-F
acts likeunlessls -CF
listflags
contains an ‘x
’, in which case it acts likels -xF
ls-F
passes its arguments to ls(1) if it is given any switches, sogenerally does the right thing.alias ls ls-F
The
ls-F
builtin can list files using different colors depending on the file type or extension. See thecolor
shell variable and theCLICOLOR_FORCE
,LSCOLORS
, andLS_COLORS
environment variables.
migrate
[-
site] pid|%
jobid ... (+)migrate
-
site (+)- The first form migrates the process or job to the site specified or the
default site determined by the system path. (TCF only)
The second form is equivalent to
in that it migrates the current process to the specified site. Migrating the shell itself can cause unexpected behavior, because the shell does not like to lose its tty. (TCF only)migrate -site
$$
newgrp
[-
] [group] (+)- Equivalent to
as per newgrp(1). Available only if the shell was so compiled; see the
exec newgrp
version
shell variable. nice
[+
number] [command]- Increments the scheduling priority for the shell by
number, or, without number, by
4. With command, runs command
at the appropriate priority. The greater the number,
the less cpu the process gets. The super-user may decrement the priority
by using
nice -number
...
command is always executed in a sub-shell, and the restrictions placed on commands in simple
if
statements apply. nohup
[command]- With command, runs command
such that it will ignore hangup signals. Note that commands may set their
own response to hangups, overriding
nohup
.Without an argument, causes the non-interactive shell only to ignore hangups for the remainder of the script. See also Signal handling and the
hup
builtin command. notify
[%
job ...]- Causes the shell to notify the user asynchronously when the status of any
of the specified jobs (or, without
%
job, the current job) changes, instead of waiting until the next prompt as is usual. job may be a number, a string, ‘’, ‘
%
’, ‘+
’, or ‘-
’ as described under Jobs. See also thenotify
shell variable. onintr
[-
|label]- Controls the action of the shell on interrupts. Without arguments,
restores the default action of the shell on interrupts, which is to
terminate shell scripts or to return to the terminal command input level.
With ‘
-
’, causes all interrupts to be ignored.With label, causes the shell to execute a
when an interrupt is received or a child process terminates because it was interrupted.goto label
onintr
is ignored if the shell is running detached and in system startup files (see FILES), where interrupts are disabled anyway. popd
[-p
] [-l
] [-n
|-v
] [+
n]- Without arguments, pops the directory stack and returns to the new top
directory.
With a number ‘
+n
’, discards the nth entry in the stack.Finally, all forms of
popd
print the final directory stack, just likedirs
. Thepushdsilent
shell variable can be set to prevent this and the-p
flag can be given to overridepushdsilent
. The-l
,-n
, and-v
flags have the same effect onpopd
as ondirs
. (+) printenv
[name] (+)- Prints the names and values of all environment variables or, with name, the value of the environment variable name.
pushd
[-p
] [-l
] [-n
|-v
] [name|+
n]- Without arguments, exchanges the top two elements of the directory stack.
If
pushdtohome
is set,pushd
without arguments acts aslikepushd ~
cd
. (+)With name, pushes the current working directory onto the directory stack and changes to name. If name is ‘
-
’ it is interpreted as the previous working directory (see Filename substitution). (+) Ifdunique
is set,pushd
removes any instances of name from the stack before pushing it onto the stack. (+)With a number ‘
+n
’, rotates the nth element of the directory stack around to be the top element and changes to it. Ifdextract
is set, however,extracts the nth directory, pushes it onto the top of the stack and changes to it. (+)pushd +n
Finally, all forms of
pushd
print the final directory stack, just likedirs
. Thepushdsilent
shell variable can be set to prevent this and the-p
flag can be given to overridepushdsilent
. The-l
,-n
, and-v
flags have the same effect onpushd
as ondirs
. (+) rehash
- Causes the internal hash table of the contents of the directories in the
path
variable to be recomputed. This is needed if theautorehash
shell variable is not set and new commands are added to directories inpath
while you are logged in. Withautorehash
, a new command will be found automatically, except in the special case where another command of the same name which is located in a different directory already exists in the hash table. Also flushes the cache of home directories built by tilde expansion. repeat
count command- The specified command, which is subject to the same
restrictions as the command in the one line
if
statement above, is executed count times. I/O redirections occur exactly once, even if count is 0. rootnode
//
nodename (+)- Changes the rootnode to
//nodename, so that
‘
/
’ will be interpreted as ‘//nodename
’. (Domain/OS only)
sched
(+)sched
[+
]hh:
mm command (+)sched
-
n (+)- The first form prints the scheduled-event list. The
sched
shell variable may be set to define the format in which the scheduled-event list is printed.The second form adds command to the scheduled-event list. For example,
> sched 11:00 echo It\'s eleven o\'clock.
causes the shell to echo
at 11 AM.It's eleven o'clock.
The time may be in 12-hour AM/PM format
> sched 5pm set prompt='[%h] It\'s after 5; go home: >'
or may be relative to the current time:
> sched +2:15 /usr/lib/uucp/uucico -r1 -sother
A relative time specification may not use AM/PM format.
The third form removes item n from the event list:
> sched 1 Wed Apr 4 15:42 /usr/lib/uucp/uucico -r1 -sother 2 Wed Apr 4 17:00 set prompt=[%h] It's after 5; go home: > > sched -2 > sched 1 Wed Apr 4 15:42 /usr/lib/uucp/uucico -r1 -sother
A command in the scheduled-event list is executed just before the first prompt is printed after the time when the command is scheduled. It is possible to miss the exact time when the command is to be run, but an overdue command will execute at the next prompt. A command which comes due while the shell is waiting for user input is executed immediately. However, normal operation of an already-running command will not be interrupted so that a scheduled-event list element may be run.
This mechanism is similar to, but not the same as, the at(1) command on some Unix systems. Its major disadvantage is that it may not run a command at exactly the specified time. Its major advantage is that because
sched
runs directly from the shell, it has access to shell variables and other structures. This provides a mechanism for changing one's working environment based on the time of day. set
set
name ...set
name=
word ...set
[-r
] [-f
|-l
] name=(
wordlist)
... (+)set
name[
index]=
word ...set
-r
(+)set
-r
name ... (+)set
-r
name=
word ... (+)- The first form of the command prints the value of all shell variables.
Variables which contain more than a single word print as a parenthesized
word list.
The second form sets name to the null string.
The third form sets name to the single word.
The fourth form sets name to the list of words in wordlist.
In all cases the value is command and filename expanded. If
-r
is specified, the value is set read-only. If-f
or-l
are specified, set only unique words keeping their order.-f
prefers the first occurrence of a word, and-l
the last.The fifth form sets the index'th component of name to word; this component must already exist.
The sixth form lists only the names of all shell variables that are read-only.
The seventh form makes name read-only, whether or not it has a value.
The eighth form is the same as the third form, but make name read-only at the same time.
These arguments can be repeated to set and/or make read-only multiple variables in a single set command. Note, however, that variable expansion happens for all arguments before any setting occurs. Note also that ‘
=
’ can be adjacent to both name and word or separated from both by whitespace, but cannot be adjacent to only one or the other. See also theunset
builtin command.
setenv
[name [value]]- Without arguments, prints the names and values of all environment
variables.
With name, sets the environment variable name to value or, without value, to the null string.
setpath
path (+)- Equivalent to setpath(1). (Mach only)
setspath
LOCAL
|site|cpu ... (+)- Sets the system execution path. (TCF only)
settc
cap value (+)- Tells the shell to believe that the terminal capability
cap (as defined in
termcap(5)) has the value
value. No sanity checking is done. Concept terminal
users may have to
to get proper wrapping at the rightmost column.
settc xn no
setty
[-d
|-q
|-x
] [-a
] [[+
|-
]mode] (+)- Controls which tty modes (see
Terminal management (+))
the shell does not allow to change.
-d
,-q
, or-x
tellssetty
to act on the ‘edit’, ‘quote’, or ‘execute’ set of tty modes respectively; without-d
,-q
, or-x
, ‘execute’ is used.Without other arguments,
setty
lists the modes in the chosen set which are fixed on (‘+
mode’) or off (‘-
mode’). The available modes, and thus the display, vary from system to system. With-a
, lists all tty modes in the chosen set whether or not they are fixed. With+
mode,-
mode, or mode, fixes mode on or off or removes control from mode in the chosen set. For example,fixes ‘setty +echok echoe
echok
’ mode on and allows commands to turn ‘echoe
’ mode on or off, both when the shell is executing commands. setxvers
[string] (+)- Set the experimental version prefix to string, or removes it if string is omitted. (TCF only)
shift
[variable]- Without arguments, discards
argv
[1] and shifts the members ofargv
to the left. It is an error forargv
not to be set or to have fewer than one word as value.With variable, performs the same function on variable.
source
[-h
] name [args ...]- The shell reads and executes commands from name. The
commands are not placed on the history list. If any
args are given, they are placed in
argv
. (+)source
commands may be nested; if they are nested too deeply the shell may run out of file descriptors. An error in asource
at any level terminates all nestedsource
commands.With
-h
, commands are placed on the history list instead of being executed, much likehistory -L
stop %
job|pid ...- Stops the specified jobs or processes which are executing in the
background. job may be a number, a string,
‘
’, ‘
%
’, ‘+
’, or ‘-
’ as described under Jobs.There is no default job; entering just
does not stop the current job.stop
suspend
- Causes the shell to stop in its tracks, much as if it had been sent a stop
signal with
^Z
. This is most often used to stop shells started by su(1).
switch
(
string)
case
str1:...
breaksw
...
default:
...
breaksw
endsw
- Each case label is successively matched, against the specified
string which is first command and filename expanded.
The file metacharacters ‘
*
’, ‘?
’, and ‘[...]
’ may be used in the case labels, which are variable expanded. If none of the labels match before adefault
label is found, then the execution begins after thedefault
label. Each case label and thedefault
label must appear at the beginning of a line. The commandbreaksw
causes execution to continue after theendsw
. Otherwise control may fall through case labels and default labels as in C. If no label matches and there is no default, execution continues after theendsw
.
telltc
(+)- Lists the values of all terminal capabilities (see termcap(5)).
termname
[termtype] (+)- Tests if termtype (or the current value of
TERM
if no termtype is given) has an entry in the hosts termcap(5) or terminfo(5) database. Prints the terminal type to stdout and returns 0 if an entry is present otherwise returns 1. time
[command]- Executes command (which must be a simple command,
not an alias, a pipeline, a command list or a parenthesized command list)
and prints a time summary as described under the
time
variable. If necessary, an extra shell is created to print the time statistic when the command completes.Without command, prints a time summary for the current shell and its children.
umask
[value]- Sets the file creation mask to value, which is given
in octal. Common values for the mask are 002, giving all access to the
group and read and execute access to others, and 022, giving read and
execute access to the group and others.
Without value, prints the current file creation mask.
unalias
pattern- Removes all aliases whose names match pattern. Thus
removes all aliases. It is not an error for nothing to be
unalias *
unalias
ed. uncomplete
pattern (+)- Removes all completions whose names match pattern.
Thus
removes all completions. It is not an error for nothing to be
uncomplete *
uncomplete
d. unhash
- Disables use of the internal hash table to speed location of executed programs.
universe
universe (+)- Sets the universe to universe. (Masscomp/RTU only)
unlimit
[-hf
] [resource]- Removes the limitation on resource or, if no
resource is specified, all
resource limitations.
With
-h
, the corresponding hard limits are removed. Only the super-user may do this.Note that
unlimit
may not exit successful, since most systems do not allowdescriptors
to be unlimited.With
-f
errors are ignored. unset
pattern- Removes all variables whose names match pattern,
unless they are read-only. Thus
removes all variables unless they are read-only; this is a bad idea.
unset *
It is not an error for nothing to be
unset
. unsetenv
pattern- Removes all environment variables whose names match
pattern. Thus
removes all environment variables; this is a bad idea.
unsetenv *
It is not an error for nothing to be
unsetenv
ed. ver
[systype [command]] (+)- Without arguments, prints
SYSTYPE
.With systype, sets
SYSTYPE
to systype.With systype and command, executes command under systype. systype may be ‘
bsd4.3
’ or ‘sys5.3
’.(Domain/OS only)
wait
- The shell waits for all background jobs. If the shell is interactive, an interrupt will disrupt the wait and cause the shell to print the names and job numbers of all outstanding jobs.
warp
universe (+)- Sets the universe to universe. (Convex/OS only)
watchlog
(+)- An alternate name for the
log
builtin command. Available only if the shell was so compiled; see theversion
shell variable. where
command (+)- Reports all known instances of command, including
aliases, builtins and executables in
path
. which
command (+)- Displays the command that will be executed by the shell after
substitutions,
path
searching, etc. The builtin command is just like which(1), but it correctly reportstcsh
aliases and builtins and is 10 to 100 times faster. See also thewhich-command
editor command.
while
(
expr)
...
end
- Executes the commands between the
while
and the matchingend
while expr (an expression, as described under Expressions) evaluates non-zero.while
andend
must appear alone on their input lines.break
andcontinue
may be used to terminate or continue the loop prematurely. If the input is a terminal, the user is prompted the first time through the loop as withforeach
.
Special aliases (+)
If set, each of these aliases executes automatically at the indicated time. They are all initially undefined.
Supported special aliases are:
beepcmd
- Runs when the shell wants to ring the terminal bell.
cwdcmd
- Runs after every change of working directory. For example, if the user is
working on an X window system using
xterm(1) and a re-parenting
window manager that supports title bars such as
twm(1) and does
> alias cwdcmd 'echo -n "^[]2;${HOST}:$cwd ^G"'
then the shell will change the title of the running xterm(1) to be the name of the host, a ‘
:
’, and the full current working directory. A fancier way to do that is> alias cwdcmd 'echo -n "^[]2;${HOST}:$cwd^G^[]1;${HOST}^G"'
This will put the hostname and working directory on the title bar but only the hostname in the icon manager menu.
Note that putting a
cd
,pushd
, orpopd
incwdcmd
may cause an infinite loop. It is the author's opinion that anyone doing so will get what they deserve. jobcmd
- Runs before each command gets executed, or when the command changes state.
This is similar to
postcmd
, but it does not print builtins.> alias jobcmd 'echo -n "^[]2\;\!#:q^G"'
then executing
will put the command string in the xterm title bar.vi foo.c
helpcommand
- Invoked by the
run-help
editor command. The command name for which help is sought is passed as sole argument. For example, if one does> alias helpcommand '\!:1 --help'
then the help display of the command itself will be invoked, using the GNU help calling convention.
Currently there is no easy way to account for various calling conventions (e.g., the customary Unix ‘
-h
’), except by using a table of many commands. periodic
- Runs every
tperiod
minutes. This provides a convenient means for checking on common but infrequent changes such as new mail. For example, if one does> set tperiod = 30 > alias periodic checknews
then the checknews(1) program runs every 30 minutes.
If
periodic
is set buttperiod
is unset or set to 0,periodic
behaves likeprecmd
. precmd
- Runs just before each prompt is printed. For example, if one does
> alias precmd date
then date(1) runs just before the shell prompts for each command.
There are no limits on what
precmd
can be set to do, but discretion should be used. postcmd
- Runs before each command gets executed.
> alias postcmd 'echo -n "^[]2\;\!#:q^G"'
then executing
will put the command string in the xterm title bar.vi foo.c
shell
- Specifies the interpreter for executable scripts which do not themselves
specify an interpreter. The first word should be a full path name to the
desired interpreter (e.g.,
‘
/bin/csh
’ or ‘/usr/local/bin/tcsh
’).
Special shell variables
The variables described in this section have special meaning to the shell.
The shell sets addsuffix
,
argv
, autologout
,
csubstnonl
, command
,
echo_style
, edit
,
gid
, group
,
home
, loginsh
,
oid
, path
,
prompt
, prompt2
,
prompt3
, shell
,
shlvl
, tcsh
,
term
, tty
,
uid
, user
, and
version
at startup; they do not change thereafter
unless changed by the user. The shell updates cwd
,
dirstack
, owd
, and
status
when necessary, and sets
logout
on logout.
The shell synchronizes group
,
home
, path
,
shlvl
, term
, and
user
with the environment variables of the same
names: whenever the environment variable changes the shell changes the
corresponding shell variable to match (unless the shell variable is
read-only) and vice versa. Note that although cwd
and PWD
have identical meanings, they are not
synchronized in this manner, and that the shell automatically converts
between the different formats of path
and
PATH
.
Supported special shell variables are:
addsuffix
(+)- If set, filename completion adds ‘
/
’ to the end of directories and a space to the end of normal files when they are matched exactly. Set by default. afsuser
(+)- If set,
autologout
's autolock feature uses its value instead of the local username for kerberos authentication. ampm
(+)- If set, all times are shown in 12-hour AM/PM format.
anyerror
(+)- This variable selects what is propagated to the value of the
status
variable. For more information see the description of thestatus
variable below. argv
- The arguments to the shell. Positional parameters are taken from
argv
, i.e., ‘$1
’ is replaced by ‘$argv[1]
’, etc. Set by default, but usually empty in interactive shells. autocorrect
(+)- If set, the
spell-word
editor command is invoked automatically before each completion attempt. autoexpand
(+)- If set, the
expand-history
editor command is invoked automatically before each completion attempt.If this is set to ‘
onlyhistory
’, then only history will be expanded and a second completion will expand filenames. autolist
(+)- If set, possibilities are listed after an ambiguous completion.
If set to ‘
ambiguous
’, possibilities are listed only when no new characters are added by completion. autologout
(+)- The first word is the number of minutes of inactivity before automatic
logout. The optional second word is the number of minutes of inactivity
before automatic locking. When the shell automatically logs out, it prints
sets the variable
auto-logout
logout
to ‘automatic
’ and exits. When the shell automatically locks, the user is required to enter their password to continue working. Five incorrect attempts result in automatic logout.Set to ‘
60
’ (automatic logout after 60 minutes, and no locking) by default in login and superuser shells, but not if the shell thinks it is running under a window system (i.e., theDISPLAY
environment variable is set), the tty is a pseudo-tty (pty) or the shell was not so compiled (see theversion
shell variable).Unset
autologout
or set it to ‘0
’ to disable automatic logout. See also theafsuser
andlogout
shell variables. autorehash
(+)- If set, the internal hash table of the contents of the directories in the
path
variable will be recomputed if a command is not found in the hash table. In addition, the list of available commands will be rebuilt for each command completion or spelling correction attempt if set to ‘complete
’ or ‘correct
’ respectively; if set to ‘always
’, this will be done for both cases. backslash_quote
(+)- If set, backslashes (`\') always quote
‘
\
’, ‘'
’, and ‘"
’. This may make complex quoting tasks easier, but it can cause syntax errors in csh(1) scripts. catalog
- The file name of the message catalog. If set,
tcsh
uses tcsh.${catalog} as a message catalog instead of default tcsh. cdpath
- A list of directories in which
cd
should search for subdirectories if they aren't found in the current directory. cdtohome
(+)- If not set,
cd
requires a directory name, and will not go to thehome
directory if it's omitted. This is set by default. color
- If set, it enables color display for the builtin
ls-F
and it passes--color=auto
to ls(1) (or--color=always
ifCLICOLOR_FORCE
is set). Alternatively, it can be set to only ‘ls-F
’ or only ‘ls
’ to enable color for a specific command. Setting it to nothing is equivalent to setting it to ‘(ls-F ls)
’. Color is disabled if the output is not directed to a terminal, unlessCLICOLOR_FORCE
is set. colorcat
- If set, it enables color escape sequence for NLS message files, and display colorful NLS messages.
command
(+)- If set, the command which was passed to the shell with the
-c
flag. compat_expr
(+)- If set, the shell will evaluate expressions right to left, like the original csh(1).
complete
(+)- If set to ‘
igncase
’, the completion becomes case insensitive.If set to ‘
enhance
’, completion ignores case and considers hyphens and underscores to be equivalent; it will also treat periods, hyphens and underscores (‘.
’, ‘-
’, and ‘_
’) as word separators.If set to ‘
Enhance
’, completion matches uppercase and underscore characters explicitly and matches lowercase and hyphens in a case-insensitive manner; it will treat periods, hyphens and underscores as word separators. continue
(+)- If set to a list of commands, the shell will continue the listed commands, instead of starting a new one.
continue_args
(+)- Same as continue, but the shell will execute:
echo `pwd` $argv > ~/.<cmd>_pause; %<cmd>
correct
(+)- If set to ‘
cmd
’, commands are automatically spelling-corrected.If set to ‘
complete
’, commands are automatically completed.If set to ‘
all
’, the entire command line is corrected. csubstnonl
(+)- If set, newlines and carriage returns in command substitution are replaced by spaces. Set by default.
cwd
- The full pathname of the current directory. See also the
dirstack
andowd
shell variables. dextract
(+)- If set,
extracts the nth directory from the directory stack rather than rotating it to the top.
pushd +n
dirsfile
(+)- The default location in which
and
dirs -S
look for a history file. If unset, ~/.cshdirs is used. Because only ~/.tcshrc is normally sourced before ~/.cshdirs,dirs -L
dirsfile
should be set in ~/.tcshrc rather than ~/.login. dirstack
(+)- An array of all the directories on the directory stack.
‘$dirstack[1]’ is the current working directory,
‘$dirstack[2]’ the first directory on the stack, etc. Note
that the current working directory is ‘$dirstack[1]’ but
‘
=0
’ in directory stack substitutions, etc. One can change the stack arbitrarily by settingdirstack
, but the first element (the current working directory) is always correct. See also thecwd
andowd
shell variables. dspmbyte
(+)- Has an effect only if ‘
dspm
’ is listed as part of theversion
shell variable.If set to ‘
euc
’, it enables display and editing EUC-kanji(Japanese) code.If set to ‘
sjis
’, it enables display and editing Shift-JIS(Japanese) code.If set to ‘
big5
’, it enables display and editing Big5(Chinese) code.If set to ‘
utf8
’, it enables display and editing Utf8(Unicode) code.If set to exactly 256 characters in the following format, it enables display and editing of original multi-byte code format:
> set dspmbyte = NNN...[250 characters]...NNN
Each character N in the 256 character value corresponds (from left to right) to the ASCII codes 0x00, 0x01, 0x02, ..., 0xfd, 0xfe, 0xff at the same index. Each character is set to number 0, 1, 2 or 3, with the meaning:
For example, if set to 256 characters starting with ‘
001322
’, the value is interpreted as:Character ASCII Multi-byte character use 0
0x00 Not used. 0
0x01 Not used. 1
0x02 First byte. 3
0x03 First byte and second byte. 2
0x04 Second byte. 2
0x05 Second byte. The GNU coreutils version of ls(1) cannot display multi-byte filenames without the
-N
(--literal
) option. If you are using this version, set the second word of dspmbyte to ‘ls
’. If not, for example,cannot display multi-byte filenames.ls-F -l
Note that this variable can only be used if KANJI and DSPMBYTE has been defined at compile time.
dunique
(+)- If set,
pushd
removes any instances of name from the stack before pushing it onto the stack. echo
- If set, each command with its arguments is echoed just before it is
executed. For non-builtin commands all expansions occur before echoing.
Builtin commands are echoed before command and filename substitution,
because these substitutions are then done selectively. Set by the
-x
command line option. echo_style
(+)- The style of the
echo
builtin. May be set to:Set by default to the local system default. The BSD and System V options are described in the echo(1) man pages on the appropriate systems.
edit
(+)- If set, the command-line editor is used. Set by default in interactive shells.
editors
(+)- A list of command names for the
run-fg-editor
editor command to match. If not set, theEDITOR
(‘ed
’ if unset) andVISUAL
(‘vi
’ if unset) environment variables will be used instead. ellipsis
(+)- If set, the ‘
%c
’, ‘%.
’, and ‘%C
’ prompt sequences (see theprompt
shell variable) indicate skipped directories with an ellipsis (‘...
’) instead of ‘/<skipped
’.>
euid
(+)- The user's effective user ID.
euser
(+)- The first matching passwd entry name corresponding to the effective user ID.
fignore
(+)- Lists file name suffixes to be ignored by completion.
filec
- In
tcsh
, completion is always used and this variable is ignored by default.If
edit
is unset, then the traditional csh(1) completion is used.If set in csh(1), filename completion is used.
gid
(+)- The user's real group ID.
globdot
(+)- If set, wild-card glob patterns will match files and directories beginning
with ‘
.
’ except for ‘.’ and ‘..’. globstar
(+)- If set, the ‘
**
’ and ‘***
’ file glob patterns will match any string of characters including ‘/
’ traversing any existing sub-directories. For example,will list all the .c files in the current directory tree.ls **.c
If used by itself, it will match zero or more sub-directories. For example,
will list any file named ‘ls /usr/include/**/time.h
time.h
’ in the /usr/include directory tree; whereaswill match any file in the /usr/include directory tree ending in ‘ls /usr/include/**time.h
time.h
’.To prevent problems with recursion, the ‘
**
’ glob-pattern will not descend into a symbolic link containing a directory. To override this, use ‘***
’. group
(+)- The user's group name.
highlight
- If set, the incremental search match (in
i-search-back
andi-search-fwd
) and the region between the mark and the cursor are highlighted in reverse video.Highlighting requires more frequent terminal writes, which introduces extra overhead. If you care about terminal performance, you may want to leave this unset.
histchars
- A string value determining the characters used in
History substitution.
The first character of its value is used as the history substitution character, replacing the default character ‘
!
’.The second character of its value replaces the character ‘
^
’ in quick substitutions. histdup
(+)- Controls handling of duplicate entries in the history list.
If set to ‘
all
’ only unique history events are entered in the history list.If set to ‘
prev
’ and the last history event is the same as the current command, then the current command is not entered in the history.If set to ‘
erase
’ and the same event is found in the history list, that old event gets erased and the current one gets inserted.Note that the ‘
prev
’ and ‘all
’ options renumber history events so there are no gaps. histfile
(+)- The default location in which
and
history -S
look for a history file.history -L
If unset, ~/.history is used.
histfile
is useful when sharing the same home directory between different machines, or when saving separate histories on different terminals. Because only ~/.tcshrc is normally sourced before ~/.history,histfile
should be set in ~/.tcshrc rather than ~/.login. histlit
(+)- If set, builtin and editor commands and the
savehist
mechanism use the literal (unexpanded) form of lines in the history list. See also thetoggle-literal-history
editor command. history
- The first word indicates the number of history events to save.
The optional second word (+) indicates the format in which history is printed; if not given, ‘
%h\t%T\t%R\n
’ is used. The format sequences are described below underprompt
; note the variable meaning of ‘%R
’.Set to ‘
100
’ by default. home
- Initialized to the home directory of the invoker. The filename expansion
of ‘
~
’ refers to this variable. ignoreeof
- If set to the empty string or ‘
0
’ and the input device is a terminal, theend-of-file
command (usually generated by the user by typing^D
on an empty line) causes the shell to printinstead of exiting. This prevents the shell from accidentally being killed. Historically this setting exited after 26 successive EOF's to avoid infinite loops.Use "exit" to leave tcsh.
If set to a number ‘n’, the shell ignores n - 1 consecutive
end-of-file
s and exits on the nth (+).If unset, ‘
1
’ is used, i.e., the shell exits on a single^D
. implicitcd
(+)- If set, the shell treats a directory name typed as a command as though it
were a request to change to that directory.
If set to
verbose
, the change of directory is echoed to the standard output.This behavior is inhibited in non-interactive shell scripts, or for command strings with more than one word. Changing directory takes precedence over executing a like-named command, but it is done after alias substitutions. Tilde and variable expansions work as expected.
inputmode
(+)- If set to ‘
insert
’ or ‘overwrite
’, puts the editor into that input mode at the beginning of each line. killdup
(+)- Controls handling of duplicate entries in the kill ring.
If set to ‘
all
’ only unique strings are entered in the kill ring.If set to ‘
prev
’ and the last killed string is the same as the current killed string, then the current string is not entered in the ring.If set to ‘
erase
’ and the same string is found in the kill ring, the old string is erased and the current one is inserted. killring
(+)- Indicates the number of killed strings to keep in memory.
Set to ‘
30
’ by default.If unset or set to less than ‘
2
’, the shell will only keep the most recently killed string.Strings are put in the killring by the editor commands that delete (kill) strings of text, e.g.
backward-delete-word
,kill-line
, etc, as well as thecopy-region-as-kill
command. Theyank
editor command will yank the most recently killed string into the command-line, whileyank-pop
(see Editor commands (+)) can be used to yank earlier killed strings. listflags
(+)- If set to ‘
x
’, ‘a
’, or ‘A
’, or any combination thereof (e.g., ‘xA
’), they are used as flags tols-F
, making it act likels -xF ls -Fa ls -FA
or a combination, for example
ls -FxA
If the first word contains ‘
a
’, shows all files (even if they start with a ‘.
’).If the first word contains ‘
A
’, shows all files but ‘.
’ and ‘..
’.If the first word contains ‘
x
’, sorts across instead of down.If the second word of
listflags
is set, it is used as the path to ls(1). listjobs
(+)- If set, all jobs are listed when a job is suspended.
If set to ‘
long
’, the listing is in long format. listlinks
(+)- If set, the
ls-F
builtin command shows the type of file to which each symbolic link points. listmax
(+)- The maximum number of items which the
list-choices
editor command will list without asking first. listmaxrows
(+)- The maximum number of rows of items which the
list-choices
editor command will list without asking first. loginsh
(+)- Set by the shell if it is a login shell. Setting or unsetting it within a
shell has no effect. See also
shlvl
. logout
(+)- Set by the shell to ‘
normal
’ before a normal logout, ‘automatic
’ before an automatic logout, and ‘hangup
’ if the shell was killed by a hangup signal (see Signal handling). See also theautologout
shell variable. mail
- A list of files and directories to check for incoming mail, optionally
preceded by a numeric word. Before each prompt, if 10 minutes have passed
since the last check, the shell checks each file and displays
(or, if
You have new mail.
mail
contains multiple files,) if the filesize is greater than zero in size and has a modification time greater than its access time.You have new mail in name.
If you are in a login shell, then no mail file is reported unless it has been modified after the time the shell has started up, to prevent redundant notifications. Most login programs will tell you whether or not you have mail when you log in.
If a file specified in
mail
is a directory, the shell will count each file within that directory as a separate message, and will reportorYou have n mails.
as appropriate. This functionality is provided primarily for those systems which store mail in this manner, such as the Andrew Mail System.You have n mails in name.
If the first word of
mail
is numeric it is taken as a different mail checking interval, in seconds.Under very rare circumstances, the shell may report
instead ofYou have mail.
You have new mail.
matchbeep
(+)- If set to ‘
never
’, completion never beeps.If set to ‘
nomatch
’, it beeps only when there is no match.If set to ‘
ambiguous
’, it beeps when there are multiple matches.If set to ‘
notunique
’, it beeps when there is one exact and other longer matches.If unset, ‘
ambiguous
’ is used. nobeep
(+)- If set, beeping is completely disabled. See also
visiblebell
. noclobber
- If set, restrictions are placed on output redirection to insure that files
are not accidentally destroyed and that
‘
>>
’ redirections refer to existing files, as described in the Input/output section.If contains ‘
ask
’, an interacive confirmation is presented, rather than an error.If contains ‘
notempty
’, ‘>
’ is allowed on empty files. noding
- If set, disable the printing of
in the
DING!
prompt
time specifiers at the change of hour. noglob
- If set, Filename substitution and Directory stack substitution (+) are inhibited. This is most useful in shell scripts which do not deal with filenames, or after a list of filenames has been obtained and further expansions are not desirable.
nokanji
(+)- If set and the shell supports Kanji (see the
version
shell variable), it is disabled so that the meta key can be used. nonomatch
- If set, a Filename
substitution or
Directory stack
substitution (+) which does not match any existing files is left
untouched rather than causing an error. It is still an error for the
substitution to be malformed. For example,
still gives an error.
echo [
nostat
(+)- A list of directories (or glob-patterns which match directories; see Filename substitution) that should not be stat(2)ed during a completion operation. This is usually used to exclude directories which take too much time to stat(2), for example /afs.
notify
- If set, the shell announces job completions asynchronously. The default is to present job completions just before printing a prompt.
oid
(+)- The user's real organization ID. (Domain/OS only)
owd
(+)- The old working directory, equivalent to the
‘
-
’ used bycd
andpushd
. See also thecwd
anddirstack
shell variables. padhour
- If set, enable the printing of padding '0' for hours, in 24 and 12 hour formats. E.g., ‘07:45:42’ versus ‘7:45:42’.
parseoctal
- To retain compatibily with older versions numeric variables starting with 0 are not interpreted as octal. Setting this variable enables proper octal parsing.
path
- A list of directories in which to look for executable commands.
A null word specifies the current directory.
If there is no
path
variable then only full path names will execute.path
is set by the shell at startup from thePATH
environment variable or, ifPATH
does not exist, to a system-dependent default, such as(/usr/local/bin /usr/bsd /bin /usr/bin .)
The shell may put ‘
.
’ first or last inpath
or omit it entirely depending on how it was compiled; see theversion
shell variable.A shell which is given neither the
-c
nor the-t
option hashes the contents of the directories inpath
after reading ~/.tcshrc and each timepath
is reset.If one adds a new command to a directory in
path
while the shell is active, one may need to do arehash
for the shell to find it. printexitvalue
(+)- If set and an interactive program exits with a non-zero status, the shell
prints
Exit status
prompt
- The string which is printed before reading each command from the terminal.
prompt
may include any of the following formatting sequences (+), which are replaced by the given information:- Format
- Prompt information
%/
- The current working directory.
%~
- The current working directory, but with one's home directory
represented by ‘
~
’ and other users' home directories represented by ‘~user
’ as per Filename substitution. ‘~user
’ substitution happens only if the shell has already used ‘~user
’ in a pathname in the current session. %c[[0]
n]
,%.[[0]
n]
- The trailing component of the current working directory, or
n trailing components if a digit
n is given. If n begins
with ‘
0
’, the number of skipped components precede the trailing component(s) in the format ‘/<skipped
’. If the>trailing
ellipsis
shell variable is set, skipped components are represented by an ellipsis so the whole becomes ‘...trailing
’. ‘~
’ substitution is done as in ‘%~
’ above, but the ‘~
’ component is ignored when counting trailing components. %C
- Like ‘
%c
’, but without ‘~
’ substitution. %h
,%!
,!
- The current history event number.
%M
- The full hostname.
%m
- The hostname up to the first
‘
.
’. %S
(%s
)- Start (stop) standout mode.
%B
(%b
)- Start (stop) boldfacing mode.
%U (%u)
- Start (stop) underline mode.
%t
,%@
- The time of day in 12-hour AM/PM format.
%T
- Like ‘
%t
’, but in 24-hour format (but see theampm
shell variable). %p
- The ‘precise’ time of day in 12-hour AM/PM format, with seconds.
%P
- Like ‘
%p
’, but in 24-hour format (but see theampm
shell variable). \
c- c is parsed as in
bindkey
. ^
c- c is parsed as in
bindkey
. %%
- A single ‘
%
’. %n
- The user name.
%N
- The effective user name.
%j
- The number of jobs.
%d
- The weekday in ‘Day’ format.
%D
- The day in ‘dd’ format.
%w
- The month in ‘Mon’ format.
%W
- The month in ‘mm’ format.
%y
- The year in ‘yy’ format.
%Y
- The year in ‘yyyy’ format.
%l
- The shell's tty.
%L
- Clears from the end of the prompt to end of the display or the end of the line.
%$
- Expands the shell or environment variable name immediately after the
‘
$
’. %#
- ‘
>
’ (or the first character of thepromptchars
shell variable) for normal users, ‘#
’ (or the second character ofpromptchars
) for the superuser. %{
string%}
- Includes
string
as a literal escape sequence. It should be used only to change terminal attributes and should not move the cursor location. This cannot be the last sequence inprompt
. %?
- The return code of the command executed just before the prompt.
%R
- In
prompt2
, the status of the parser. Inprompt3
, the corrected string. Inhistory
, the history string.
‘
%B
’, ‘%S
’, ‘%U
’, and ‘%{string
’ are available in only eight-bit-clean shells; see the%}
version
shell variable.The bold, standout and underline sequences are often used to distinguish a superuser shell. For example,
> set prompt = "%m [%h] %B[%@]%b [%/] you rang? "
tut [37]
[2:54pm]
[/usr/accts/sys] you rang? _
If ‘
%t
’, ‘%@
’, ‘%T
’, ‘%p
’, or ‘%P
’ is used, andnoding
is not set, then printon the change of hour (i.e, ‘:00’ minutes) instead of the actual time.DING!
Set by default to ‘
%#
’ in interactive shells. prompt2
(+)- The string with which to prompt in
while
andforeach
loops and after lines ending in ‘\
’. The same format sequences may be used as inprompt
; note the variable meaning of ‘%R
’.Set by default to ‘
%R?
’ in interactive shells. prompt3
(+)- The string with which to prompt when confirming automatic spelling
correction. The same format sequences may be used as in
prompt
; note the variable meaning of ‘%R
’.Set by default to ‘
CORRECT>%R (y|n|e|a)?
’ in interactive shells. promptchars
(+)- If set (to a two-character string), the
‘
%#
’ formatting sequence in theprompt
shell variable is replaced with the first character for normal users and the second character for the superuser. pushdtohome
(+)- If set,
pushd
without arguments doeslikepushd ~
cd
. pushdsilent
(+)- If set,
pushd
andpopd
do not print the directory stack. recexact
(+)- If set, completion completes on an exact match even if a longer match is possible.
recognize_only_executables
(+)- If set, command listing displays only files in the path that are executable. Slow.
rmstar
(+)- If set, the user is prompted before
is executed.
rm *
rprompt
(+)- The string to print on the right-hand side of the screen (after the
command input) when the prompt is being displayed on the left. It
recognizes the same formatting characters as
prompt
. It will automatically disappear and reappear as necessary, to ensure that command input isn't obscured, and will appear only if the prompt, command input, and itself will fit together on the first line.If
edit
isn't set, thenrprompt
will be printed after the prompt and before the command input. savedirs
(+)- If set, the shell does
before exiting.
dirs -S
If the first word is set to a number, at most that many directory stack entries are saved.
savehist
- If set, the shell does
before exiting.
history -S
If the first word is set to a number, at most that many lines are saved. (The number should be less than or equal to the number
history
entries; if it is set to greater than the number ofhistory
settings, onlyhistory
entries will be saved.)If the second word is set to ‘
merge
’, the history list is merged with the existing history file instead of replacing it (if there is one) and sorted by time stamp and the most recent events are retained.If the second word is set to ‘
merge
’ and the third word is set to ‘lock
’, the history file update will be serialized with other shell sessions that would possibly like to merge history at exactly the same time. (+) sched
(+)- The format in which the
sched
builtin command prints scheduled events; if not given, ‘%h\t%T\t%R\n
’ is used. The format sequences are described above underprompt
; note the variable meaning of ‘%R
’. shell
- The file in which the shell resides. This is used in forking shells to interpret files which have execute bits set, but which are not executable by the system. (See the description of Builtin and non-builtin command execution.) Initialized to the (system-dependent) home of the shell.
shlvl
(+)- The number of nested shells. Reset to 1 in login shells. See also
loginsh
. status
- The exit status from the last command or backquote expansion, or any
command in a pipeline is propagated to
status
. (This is also the default csh(1) behavior.) This default does not match what POSIX mandates (to return the status of the last command only). To match the POSIX behavior, you need to unsetanyerror
.If the
anyerror
variable is unset, the exit status of a pipeline is determined only from the last command in the pipeline, and the exit status of a backquote expansion is not propagated tostatus
.If a command terminated abnormally, then 0200 is added to the status. Builtin commands which fail return exit status ‘
1
’, all other builtin commands return status ‘0
’. symlinks
(+)- Can be set to several different values to control symbolic link
(‘symlink’) resolution:
If set to ‘
chase
’, whenever the current directory changes to a directory containing a symbolic link, it is expanded to the real name of the directory to which the link points. This does not work for the user's home directory; this is a bug.If set to ‘
ignore
’, the shell tries to construct a current directory relative to the current directory before the link was crossed. This means thatthrough a symbolic link and thencd
returns one to the original directory. This affects only builtin commands and filename completion.cd ..
If set to ‘
expand
’, the shell tries to fix symbolic links by actually expanding arguments which look like path names. This affects any command, not just builtins. Unfortunately, this does not work for hard-to-recognize filenames, such as those embedded in command options. Expansion may be prevented by quoting. While this setting is usually the most convenient, it is sometimes misleading and sometimes confusing when it fails to recognize an argument which should be expanded. A compromise is to use ‘ignore
’ and use the editor commandnormalize-path
(bound by default to^X-n
) when necessary.Some examples are in order. First, let's set up some play directories:
> cd /tmp > mkdir from from/src to > ln -s from/src to/dst
Here's the behavior with
symlinks
unset,> cd /tmp/to/dst; echo $cwd /tmp/to/dst > cd ..; echo $cwd /tmp/from
Here's the behavior with
symlinks
set to ‘chase
’,> cd /tmp/to/dst; echo $cwd /tmp/from/src > cd ..; echo $cwd /tmp/from
Here's the behavior with
symlinks
set to ‘ignore
’,> cd /tmp/to/dst; echo $cwd /tmp/to/dst > cd ..; echo $cwd /tmp/to
Here's the behavior with
symlinks
set to ‘expand
’.> cd /tmp/to/dst; echo $cwd /tmp/to/dst > cd ..; echo $cwd /tmp/to > cd /tmp/to/dst; echo $cwd /tmp/to/dst > cd ".."; echo $cwd /tmp/from > /bin/echo .. /tmp/to > /bin/echo ".." ..
Note that ‘
expand
’ expansion:- Works just like ‘
ignore
’ for builtins likecd
. - Is prevented by quoting.
- Happens before filenames are passed to non-builtin commands.
- Works just like ‘
tcsh
(+)- The version number of the shell in the format ‘R.VV.PP’, where ‘R’ is the major release number, ‘VV’ the current version, and ‘PP’ the patchlevel.
term
- The terminal type. Usually set in ~/.login as described under Startup and shutdown.
time
- If set to a number, then the
time
builtin executes automatically after each command which takes more than that many CPU seconds.If there is a second word, it is used as a format string for the output of the
time
builtin.(u) The following sequences may be used in the
time
format string:- Format
- Time information
%U
- The time the process spent in user mode in cpu seconds.
%S
- The time the process spent in kernel mode in cpu seconds.
%E
- The elapsed (wall clock) time in seconds.
%P
- The CPU percentage computed as (%U + %S) / %E.
%W
- Number of times the process was swapped.
%X
- The average amount in (shared) text space used in Kbytes.
%D
- The average amount in (unshared) data/stack space used in Kbytes.
%K
- The total space used (%X + %D) in Kbytes.
%M
- The maximum memory the process had in use at any time in Kbytes.
%F
- The number of major page faults (page needed to be brought from disk).
%R
- The number of minor page faults.
%I
- The number of input operations.
%O
- The number of output operations.
%r
- The number of socket messages received.
%s
- The number of socket messages sent.
%k
- The number of signals received.
%w
- The number of voluntary context switches (waits).
%c
- The number of involuntary context switches.
Only the first four sequences are supported on systems without BSD resource limit functions. The default time format is ‘
%Uu %Ss %E %P %X+%Dk %I+%Oio %Fpf+%Ww
’ for systems that support resource usage reporting and ‘%Uu %Ss %E %P
’ for systems that do not.Under Sequent's DYNIX/ptx, ‘
%X
’, ‘%D
’, ‘%K
’, ‘%r
’, and ‘%s
’ are not available, but the following additional sequences are:- Format
- Description Sequent DYNIX/ptx time information
%Y
- The number of system calls performed.
%Z
- The number of pages which are zero-filled on demand.
%i
- The number of times a process's resident set size was increased by the kernel.
%d
- The number of times a process's resident set size was decreased by the kernel.
%l
- The number of read system calls performed.
%m
- The number of write system calls performed.
%p
- The number of reads from raw disk devices.
%q
- The number of writes to raw disk devices.
and the default time format is ‘
%Uu %Ss %E %P %I+%Oio %Fpf+%Ww
’.Note that the CPU percentage can be higher than 100% on multi-processors.
tperiod
(+)- The period, in minutes, between executions of the
periodic
special alias. tty
(+)- The name of the tty, or empty if not attached to one.
uid
(+)- The user's real user ID.
user
- The user's login name.
verbose
- If set, causes the words of each command to be printed, after history
substitution (if any). Set by the
-v
command line option. version
(+)- The version ID stamp. It contains the shell's version number (see
tcsh
), origin, release date, vendor, operating system and machine (seeVENDOR
,OSTYPE
, andMACHTYPE
) and a comma-separated list of options which were set at compile time. Options which are set by default in the distribution are noted.Supported
version
options include:- Option
- Description
8b
- The shell is eight bit clean; default.
7b
- The shell is not eight bit clean.
wide
- The shell is multi-byte encoding clean (like UTF-8).
nls
- The system's NLS is used; default for systems with NLS.
lf
- Login shells execute /etc/csh.login before instead of after /etc/csh.cshrc and ~/.login before instead of after ~/.tcshrc and ~/.history.
dl
- ‘
.
’ is put last inpath
for security; default. nd
- ‘
.
’ is omitted frompath
for security. vi
- vi(1)-style editing is the default rather than emacs(1)-style.
dtr
- Login shells drop DTR when exiting.
bye
bye
is a synonym forlogout
andlog
is an alternate name forwatchlog
.al
autologout
is enabled; default.kan
- Kanji is used if appropriate according to locale settings, unless the
nokanji
shell variable is set. sm
- The system's malloc(3) is used.
hb
- The
convention is emulated when executing shell scripts.
#!interpreter arg
...
ng
- The
newgrp
builtin is available. rh
- The shell attempts to set the
REMOTEHOST
environment variable. afs
- The shell verifies your password with the kerberos server if local
authentication fails. The
afsuser
shell variable or theAFSUSER
environment variable override your local username if set.
An administrator may enter additional strings to indicate differences in the local version.
vimode
(+)- If unset, various key bindings change behavior to be more
emacs(1)-style: word boundaries
are determined by
wordchars
versus other characters.If set, various key bindings change behavior to be more vi(1)-style: word boundaries are determined by
wordchars
versus whitespace versus other characters; cursor behavior depends upon current vi mode (command, delete, insert, replace).This variable is unset by
bindkey
-e
and set bybindkey
-v
.vimode
may be explicitly set or unset by the user after thosebindkey
operations if required. visiblebell
(+)- If set, a screen flash is used rather than the audible bell. See also
nobeep
. watch
(+)- A list of user/terminal pairs to watch for logins and logouts. If either
the user is ‘
any
’ all terminals are watched for the given user and vice versa. Settingwatch
towatches all users and terminals. For example,(any any)
set watch = (george ttyd1 any console $user any)
reports activity of the user ‘
george
’ on ‘ttyd1
’, any user on the console, and oneself (or a trespasser) on any terminal.Logins and logouts are checked every 10 minutes by default, but the first word of
watch
can be set to a number to check every so many minutes. For example,set watch = (1 any any)
reports any login/logout once every minute. For the impatient, the
log
builtin command triggers awatch
report at any time. All current logins are reported (as with thelog
builtin) whenwatch
is first set.The
who
shell variable controls the format ofwatch
reports. who
(+)- The format string for
watch
messages. The following sequences are replaced by the given information:- Format
- Who information
%n
- The name of the user who logged in/out.
%a
- The observed action, i.e., ‘logged on’, ‘logged off’, or ‘replaced olduser on’.
%l
- The terminal (tty) on which the user logged in/out.
%M
- The full hostname of the remote host, or ‘local’ if the login/logout was from the local host.
%m
- The hostname of the remote host up to the first ‘.’. The full name is printed if it is an IP address or an X Window System display.
‘
%M
’ and ‘%m
’ are available on only systems that store the remote hostname in /etc/utmp.If unset,
is used, or%n has %a %l from %m.
on systems which don't store the remote hostname.%n has %a %l.
wordchars
(+)- A list of non-alphanumeric characters to be considered part of a word by
the
forward-word
,backward-word
, etc., editor commands.If unset, the default value is determined based on the state of
vimode
: ifvimode
is unset, ‘*?_-.[]~=
’ is used as the default; ifvimode
is set, ‘_
’ is used as the default.
ENVIRONMENT
AFSUSER
(+)- Equivalent to the
afsuser
shell variable. CLICOLOR_FORCE
- Color sequences for
ls-F
are normally disabled if the output is not directed to a terminal. This can be overridden by setting this variable, which also changes thels-F
invocation of ls(1) to use--color=always
instead of--color=auto
.Note that
color
must be set for this environment variable to be effective; by itselfCLICOLOR_FORCE
does not enable colorls-F
. COMMAND_LINE
- Set by
tcsh
to the current command line when invoking programs for thecomplete
list mode ‘`...`
’. Seecomplete
in Builtin commands. COLUMNS
- The number of columns in the terminal. See Terminal management (+).
DISPLAY
- Used by X Window System (see X(1)).
If set, the shell does not set
autologout
. EDITOR
- The pathname to a default editor. Used by the
run-fg-editor
editor command if the theeditors
shell variable is unset. See also theVISUAL
environment variable. GROUP
(+)- Equivalent to the
group
shell variable. HOME
- Equivalent to the
home
shell variable. HOST
(+)- Initialized to the name of the machine on which the shell is running, as determined by the gethostname(2) system call.
HOSTTYPE
(+)- Initialized to the type of machine on which the shell is running, as determined at compile time. This variable is obsolete and will be removed in a future version.
HPATH
(+)- A
‘
:
’-separated list of directories in which therun-help
editor command looks for command documentation. LANG
- Gives the preferred character environment. See Native Language System support (+).
LC_CTYPE
- If set, only ctype character handling is changed. See Native Language System support (+).
LINES
- The number of lines in the terminal. See Terminal management (+).
LSCOLORS
- One of two environment variables that may be used to define the per-file
colors used by
ls-F
(along withLS_COLORS
). This variable is used by some BSD versions of ls(1).On
tcsh
startup,LS_COLORS
takes priority overLSCOLORS
. If bothLSCOLORS
orLS_COLORS
aresetenv
, the most recentsetenv
is used. IfLSCOLORS
isunsetenv
whileLS_COLORS
is stillsetenv
, thenLS_COLORS
is parsed again (with any warnings suppressed) to reapply its settings.This variable is a 22 character string containing a concatenation of 11 pairs of the format fb, where f is the foreground color and b is the background color. If fewer than 11 pairs are provided, default colors are used for the remaining entries. If more than 11 pairs are provided, the extra values are ignored.
The order of the color attribute pairs to the equivalent
LS_COLORS
variable, the file type, and default color, is as follows:Index Var File type. [Default color] 1 di
Directory. [Bold blue] 2 ln
Symbolic link. [Bold cyan] 3 so
Socket. [Bold magenta] 4 pi
Named pipe (FIFO). [Yellow (or brown)] 5 ex
Executable file. [Bold green] 6 bd
Block device. [Bold yellow] 7 cd
Character device. [Bold yellow] 8 su
Setuid file. [White on red] 9 sg
Setgid file. [Black on yellow] 10 tw
Sticky and other writable directory. [Black on green] 11 ow
Other writable but not sticky directory. [Blue on green] The color code designators are as follows:
- Code
- Description
a
- Black.
b
- Red.
c
- Green.
d
- Yellow (or brown).
e
- Blue.
f
- Magenta.
g
- Cyan.
h
- Light grey.
A
- Bold black, usually shows up as dark grey.
B
- Bold red.
C
- Bold green.
D
- Bold yellow.
E
- Bold blue.
F
- Bold magenta.
G
- Bold cyan.
H
- Bold light grey; looks like bright white.
x
- Default foreground or background.
Note that the above are standard ANSI colors. The actual display may differ depending on the color capabilities of the terminal in use.
The default colors are as per the color variables in
LS_COLORS
, and are not the same default colors as those used by some BSD versions of ls(1). LS_COLORS
- One of two environment variables that may be used to define the per-file
colors used by
ls-F
(along withLSCOLORS
). This variable is used by the GNU coreutils version of ls(1) and may be setup by dircolors(1).On
tcsh
startup,LS_COLORS
takes priority overLSCOLORS
. If bothLSCOLORS
orLS_COLORS
aresetenv
, the most recentsetenv
is used. IfLS_COLORS
isunsetenv
whileLSCOLORS
is stillsetenv
, thenLSCOLORS
is parsed again (with any warnings suppressed) to reapply its settings.The format of this variable is reminiscent of the termcap(5) file format; a ‘
:
’-separated list of expressions of the form"
xx=
value"
or"*
ext=
value"
.The first form
"
xx=
value"
, where"
xx"
is a two-character variable name, supports the following variables, their associated default ISO 6429 color code or escape sequences, and file type:Var Default File type. [Default color] no
0
Normal (non-filename) text. fi
0
Regular file. di
01;34
Directory. [Bold blue] ln
01;36
Symbolic link. [Bold cyan] pi
33
Named pipe (FIFO). [Yellow (or brown)] so
01;35
Socket. [Bold magenta] do
01;35
Door. [Bold magenta] bd
01;33
Block device. [Bold yellow] cd
01;33
Character device. [Bold yellow] ex
01;32
Executable file. [Bold green] mi
(none) Missing file (orphaned symbolic link target). Defaults to fi
.or
(none) Orphaned (broken) symbolic link. Defaults to ln
.lc
^[[
Left code. rc
m
Right code. ec
(none) End code. Replaces lc
+no
+rc
.su
37;41
Setuid file. [White on red] sg
30;43
Setgid file. [Black on yellow] tw
30;42
Sticky and other writable directory. [Black on green] ow
34;42
Other writable but not sticky directory. [Blue on green] st
37;44
Sticky but not other writable directory. [White on blue] mh
(none) File with multiple hard links. You need to include only the variables you want to change from the default.
The second form
"*
ext=
value"
colorizes file names based on extension. For example, using ISO 6429 codes, to color all C-language source files blue you would specify"*.c=34"
. This would color all files ending in ‘.c
’ in blue foreground (34) color.Control characters can be written either in C-style-escaped notation, or in stty-like ^-notation. The C-style notation adds ‘
^[
’ for Escape, ‘_
’ for a normal space character, and ‘?
’ for Delete. In addition, the ‘^[
’ escape character can be used to override the default interpretation of ‘^[
’, ‘^
’, ‘:
’, and ‘=
’.Each filename will be output to the terminal as
lc color-code
rc
filenameec
If the ‘
ec
’ code is undefined, the sequencewill be used instead. This is generally more convenient to use, but less general.lc no rc
The left code (‘
lc
’), right code (‘rc
’), and end codes (‘ec
’) are provided so you don't have to type common parts over and over again and to support weird terminals; you will generally not need to change them at all unless your terminal does not use ISO 6429 color codes but a different system.If your terminal uses ISO 6429 color codes, you can compose the type codes (i.e., all except the ‘
lc
’, ‘rc
’, and ‘ec
’ codes) from numerical ISO 6429 color codes separated by ‘;
’. For example, ‘01;32
’ is bright green foreground with default background.The most common ISO 6429 color codes are:
- Color
- Description
0
- To restore default color.
1
- Bold / brighter colors.
4
- Underlined text.
5
- Flashing text.
30
- Black foreground.
31
- Red foreground.
32
- Green foreground.
33
- Yellow (or brown) foreground.
34
- Blue foreground.
35
- Magenta foreground.
36
- Cyan foreground.
37
- White (or gray) foreground.
40
- Black background.
41
- Red background.
42
- Green background.
43
- Yellow (or brown) background.
44
- Blue background.
45
- Magenta background.
46
- Cyan background.
47
- White (or gray) background.
Not all ISO 6429 color codes will work on all systems or display devices.
A few terminal programs do not recognize the default end code properly. If all text gets colorized after you do a directory listing, try changing the ‘
no
’ and ‘fi
’ codes from 0 to the numerical codes for your standard foreground and background colors.For symbolic links the ‘
ln
’ keyword can be set to ‘target
’, which makes the file color the same as the color of the link target. MACHTYPE
(+)- The machine type (microprocessor class or machine model), as determined at compile time.
NOREBIND
(+)- If set, printable characters are not rebound to
self-insert-command
. See Native Language System support (+). OSTYPE
(+)- The operating system, as determined at compile time.
PATH
- A
‘
:
’-separated list of directories in which to look for executables. Equivalent to thepath
shell variable, but in a different format. PWD
(+)- Equivalent to the
cwd
shell variable, but not synchronized to it; updated only after an actual directory change. REMOTEHOST
(+)- The host from which the user has logged in remotely, if this is the case
and the shell is able to determine it. Set only if the shell was so
compiled; see the
version
shell variable. SHLVL
(+)- Equivalent to the
shlvl
shell variable. SYSTYPE
(+)- The current system type. (Domain/OS only)
TERM
- Equivalent to the
term
shell variable. TERMCAP
- The terminal capability string. See Terminal management (+).
USER
- Equivalent to the
user
shell variable. VENDOR
(+)- The vendor, as determined at compile time.
VISUAL
- The pathname to a default full-screen editor. Used by the
run-fg-editor
editor command if the theeditors
shell variable is unset. See also theEDITOR
environment variable.
FILES
- /etc/csh.cshrc
- Read first by every shell.
ConvexOS, Stellix and Intel use /etc/cshrc.
NeXTs use /etc/cshrc.std.
A/UX, AMIX, Cray and IRIX have no equivalent in csh(1), but read this file in
tcsh
anyway.Solaris 2.x does not have it either, but
tcsh
reads /etc/.cshrc.(+)
- /etc/csh.login
- Read by login shells after /etc/csh.cshrc.
ConvexOS, Stellix and Intel use /etc/login.
NeXTs use /etc/login.std.
Solaris 2.x uses /etc/.login.
A/UX, AMIX, Cray and IRIX use /etc/cshrc.
- ~/.tcshrc (+)
- Read by every shell after /etc/csh.cshrc or its equivalent.
- ~/.cshrc
- Read by every shell, if ~/.tcshrc doesn't exist,
after /etc/csh.cshrc or its equivalent.
This manual uses ‘~/.tcshrc’ to mean “~/.tcshrc or, if ~/.tcshrc is not found, ~/.cshrc”.
- ~/.history
- Read by login shells after ~/.tcshrc if
savehist
is set, but see alsohistfile
. - ~/.login
- Read by login shells after ~/.tcshrc or
~/.history.
The shell may be compiled to read ~/.login before instead of after ~/.tcshrc and ~/.history; see the
version
shell variable. - ~/.cshdirs (+)
- Read by login shells after ~/.login if
savedirs
is set, but see alsodirsfile
. - /etc/csh.logout
- Read by login shells at logout.
ConvexOS, Stellix and Intel use /etc/logout. NeXTs use /etc/logout.std.
A/UX, AMIX, Cray and IRIX have no equivalent in csh(1), but read this file in
tcsh
anyway.Solaris 2.x does not have it either, but
tcsh
reads /etc/.logout. (+) - ~/.logout
- Read by login shells at logout after /etc/csh.logout or its equivalent.
- /bin/sh
- Used to interpret shell scripts not starting with a
‘
#
’. - /tmp/sh*
- Temporary file for ‘
<<
’. - /etc/passwd
- Source of home directories for ‘~name’ substitutions.
The order in which startup files are read may differ if the shell
was so compiled; see Startup and
shutdown and the version
shell variable.
NEW FEATURES (+)
This manual describes tcsh
as a single
entity, but experienced csh(1) users
will want to pay special attention to tcsh
's new
features.
A command-line editor, which supports emacs(1)-style or vi(1)-style key bindings. See The command-line editor (+) and Editor commands (+).
Programmable, interactive word completion and listing. See
Completion and listing
(+) and the complete
and
uncomplete
builtin commands.
Spelling correction (+) of filenames, commands and variables.
Editor commands (+)
which perform other useful functions in the middle of typed commands,
including documentation lookup (run-help
), quick
editor restarting (run-fg-editor
), and command
resolution (which-command
).
An enhanced history mechanism. Events in the history list are
time-stamped. See also the history
command and its
associated shell variables, the previously undocumented
‘#
’ event specifier and new modifiers
under History substitution,
the down-history
,
expand-history
,
history-search-backward
,
history-search-forward
,
i-search-back
, i-search-fwd
,
toggle-literal-history
,
vi-search-back
,
vi-search-fwd
, and
up-history
editor commands and the
histlit
shell variable.
Enhanced directory parsing and directory stack handling. See the
cd
, pushd
,
popd
, and dirs
commands and
their associated shell variables, the description of
Directory stack
substitution (+), the dirstack
,
owd
, and symlinks
shell
variables and the normalize-command
and
normalize-path
editor commands.
Negation in glob-patterns. See Filename substitution.
New File inquiry
operators and a filetest
builtin which uses
them.
A variety of Automatic, periodic and timed events (+) including scheduled events, special aliases, automatic logout and terminal locking, command timing and watching for logins and logouts.
Support for the Native Language System (see
Native Language
System support (+)), OS variant features (see
OS variant support (+) and
the echo_style
shell variable) and system-dependent
file locations (see FILES).
Extensive terminal-management capabilities. See Terminal management (+).
New builtin commands including builtins
,
hup
, ls-F
,
newgrp
, printenv
,
which
, and where
.
New variables that make useful information easily available to the
shell. See the gid
, loginsh
,
oid
, shlvl
,
tcsh
, tty
,
uid
, and version
shell
variables and the HOST
,
REMOTEHOST
, VENDOR
,
OSTYPE
, and MACHTYPE
environment variables.
A new syntax for including useful information in the prompt string
(see prompt
), and special prompts for loops and
spelling correction (see prompt2
and
prompt3
).
Read-only variables. See Variable substitution.
THE T IN TCSH
In 1964, DEC produced the PDP-6. The PDP-10 was a later re-implementation. It was re-christened the DECsystem-10 in 1970 or so when DEC brought out the second model, the KI10.
TENEX was created at Bolt, Beranek & Newman (a Cambridge, Massachusetts think tank) in 1972 as an experiment in demand-paged virtual memory operating systems. They built a new pager for the DEC PDP-10 and created the OS to go with it. It was extremely successful in academia.
In 1975, DEC brought out a new model of the PDP-10, the KL10; they intended to have only a version of TENEX, which they had licensed from BBN, for the new box. They called their version TOPS-20 (their capitalization is trademarked). A lot of TOPS-10 users (`The OPerating System for PDP-10') objected; thus DEC found themselves supporting two incompatible systems on the same hardware--but then there were 6 on the PDP-11!
TENEX, and TOPS-20 to version 3, had command completion via a user-code-level subroutine library called ULTCMD. With version 3, DEC moved all that capability and more into the monitor (`kernel' for you Unix types), accessed by the COMND% JSYS (`Jump to SYStem' instruction, the supervisor call mechanism [are my IBM roots also showing?]).
The creator of tcsh was impressed by this feature and several others of TENEX and TOPS-20, and created a version of csh which mimicked them.
LIMITATIONS
The system limits argument lists to ARG_MAX characters.
The number of arguments to a command which involves filename expansion is limited to 1/6th the number of characters allowed in an argument list.
Command substitutions may substitute no more characters than are allowed in an argument list.
To detect looping, the shell restricts the number of
alias
substitutions on a single line to 20.
SEE ALSO
csh(1), dircolors(1), emacs(1), ls(1), newgrp(1), setpath(1), sh(1), stty(1), su(1), tset(1), vi(1), x(1), access(2), execve(2), fork(2), killpg(2), pipe(2), setrlimit(2), sigvec(2), stat(2), umask(2), vfork(2), wait(2), malloc(3), setlocale(3), tty(4), a.out(5), termcap(5), environ(7), termio(7), Introduction to the C Shell
VERSION
This manual documents tcsh 6.24.14 (Astron) 2024-11-26.
AUTHORS
- William Joy.
-
Original author of csh(1). - J.E. Kulp,
- IIASA, Laxenburg, Austria.
Job control and directory stack features. - Ken Greer,
- HP Labs, 1981.
File name completion. - Mike Ellis,
- Fairchild, 1983.
Command name recognition/completion. - Paul Placeway,
- Ohio State CIS Dept., 1983-1993.
Command line editor, prompt routines, new glob syntax and numerous fixes and speedups. - Karl Kleinpaste,
- CCI, 1983-4.
Special aliases, directory stack extraction stuff, login/logout watch, scheduled events, and the idea of the new prompt format. - Rayan Zachariassen,
- University of Toronto, 1984.
ls-F
andwhich
builtins and numerous bug fixes, modifications and speedups. - Chris Kingsley,
- Caltech.
Fast storage allocator routines. - Chris Grevstad,
- TRW, 1987.
Incorporated 4.3BSD csh(1) intotcsh
. - Christos S. Zoulas,
- Cornell U. EE Dept., 1987-94.
Ports to HPUX, SVR2 and SVR3, a SysV version of getwd.c, SHORT_STRINGS support and a new version of sh.glob.c. - James J Dempsey,
- BBN, and Paul Placeway, OSU, 1988.
A/UX port. - Daniel Long,
- NNSC, 1988.
wordchars
. - Patrick Wolfe,
- Kuck and Associates, Inc., 1988.
vi
mode cleanup. - David C Lawrence,
- Rensselaer Polytechnic Institute, 1989.
autolist
and ambiguous completion listing. - Alec Wolman,
- DEC, 1989.
Newlines in the prompt. - Matt Landau,
- BBN, 1989.
~/.tcshrc. - Ray Moody,
- Purdue Physics, 1989.
Magic space bar history expansion. - Mordechai ????,
- Intel, 1989.
printprompt
() fixes and additions. - Kazuhiro Honda,
- Dept. of Computer Science, Keio University, 1989.
Automatic spelling correction andprompt3
. - Per Hedeland,
- Ellemtel, Sweden, 1990-.
Various bugfixes, improvements and manual updates. - Hans J. Albertsson,
- Sun Sweden.
ampm
,settc
, andtelltc
. - Michael Bloom.
-
Interrupt handling fixes. - Michael Fine,
- Digital Equipment Corp.
Extended key support. - Eric Schnoebelen,
- Convex, 1990.
Convex support, lots of csh(1) bug fixes, save and restore of directory stack. - Ron Flax,
- Apple, 1990.
A/UX 2.0 (re)port. - Dan Oscarsson,
- LTH Sweden, 1990.
NLS support and simulated NLS support for non NLS sites, fixes. - Johan Widen,
- SICS Sweden, 1990.
shlvl
, Mach support,correct-line
, 8-bit printing. - Matt Day,
- Sanyo Icon, 1990.
POSIX termio support, SysV limit fixes. - Jaap Vermeulen,
- Sequent, 1990-91.
Vi mode fixes, expand-line, window change fixes, Symmetry port. - Martin Boyer,
- Institut de recherche d'Hydro-Quebec, 1991.
autolist
beeping options, modified the history search to search for the whole string from the beginning of the line to the cursor. - Scott Krotz,
- Motorola, 1991.
Minix port. - David Dawes,
- Sydney U. Australia, Physics Dept., 1991.
SVR4 job control fixes. - Kimmo Suominen,
- 1991-.
Various portability and other fixes. Added ‘$''
’ (dollar-single-quotes). - Jose Sousa,
- Interactive Systems Corp., 1991.
Extendedvi
fixes andvi
delete command. - Marc Horowitz,
- MIT, 1991.
ANSIfication fixes, new exec hashing code, imake fixes,where
. - Luke Mewburn,
- 1991-.
Enhanced directory printing inprompt
. Addedellipsis
andrprompt
.vimode
improvements. Manual page improvements. - Bruce Sterling Woodcock,
- sterling@netcom.com, 1991-1995.
ETA and Pyramid port, Makefile and lint fixes,ignoreeof=
n addition, and various other portability changes and bug fixes. - Jeff Fink,
- 1992.
complete-word-fwd
andcomplete-word-back
. - Harry C. Pulley,
- 1992.
Coherent port. - Andy Phillips,
- Mullard Space Science Lab U.K., 1992.
VMS-POSIX port. - Beto Appleton,
- IBM Corp., 1992.
Walking process group fixes, csh(1) bug fixes, POSIX file tests, POSIX SIGHUP. - Scott Bolte,
- Cray Computer Corp., 1992.
CSOS port. - Kaveh R. Ghazi,
- Rutgers University, 1992.
Tek, m88k, Titan and Masscomp ports and fixes. Added autoconf support. - Mark Linderman,
- Cornell University, 1992.
OS/2 port. - Mika Liljeberg,
- liljeber@kruuna.Helsinki.FI, 1992.
Linux port. - Tim P. Starrin,
- NASA Langley Research Center Operations, 1993.
Read-only variables. - Dave Schweisguth,
- Yale University, 1993-4.
New man page and tcsh.man2html. - Larry Schwimmer,
- Stanford University, 1993.
AFS and HESIOD patches. - Edward Hutchins,
- Silicon Graphics Inc., 1996.
Added implicit cd. - Martin Kraemer,
- 1997.
Ported to Siemens Nixdorf EBCDIC machine. - Amol Deshpande,
- Microsoft, 1997.
Ported to WIN32 (Windows/95 and Windows/NT); wrote all the missing library and message catalog code to interface to Windows. - Taga Nayuta,
- 1998.
Color ls additions.
THANKS TO
Bryan Dunlap, Clayton Elwell, Karl Kleinpaste, Bob Manson, Steve Romig, Diana Smetters, Bob Sutterfield, Mark Verber, Elizabeth Zwicky and all the other people at Ohio State for suggestions and encouragement
All the people on the net, for putting up with, reporting bugs in, and suggesting new additions to each and every version
Richard M. Alderson III, for writing the T in tcsh section
BUGS
When a suspended command is restarted, the shell prints the directory it started in if this is different from the current directory. This can be misleading (i.e., wrong) as the job may have changed directories internally.
Shell builtin functions are not stoppable/restartable. Command sequences of the form
a ; b ; c
b
’, the shell will then immediately
execute ‘c
’. This is especially
noticeable if this expansion results from an alias
. It
suffices to place the sequence of commands in
‘()
’'s to force it to a subshell, i.e.,
( a ; b ; c )
Control over tty output after processes are started is primitive; perhaps this will inspire someone to work on a good virtual terminal interface. In a virtual terminal interface much more interesting things could be done with output control.
Alias substitution is most often used to clumsily simulate shell procedures; shell procedures should be provided rather than aliases.
Control structures should be parsed rather than being recognized
as built-in commands. This would allow control commands to be placed
anywhere, to be combined with ‘|
’, and
to be used with ‘&
’ and
‘;
’ metasyntax.
foreach
doesn't ignore here documents when
looking for its end
.
It should be possible to use the
‘:
’ modifiers on the output of command
substitutions.
The screen update for lines longer than the screen width is very
poor if the terminal cannot move the cursor up (i.e., terminal type
‘dumb
’).
HPATH
and NOREBIND
don't need to be environment variables.
Glob-patterns which do not use
‘?
’,
‘*
’, or
‘[]
’, or which use
‘{}
’ or
‘~
’ are not negated correctly.
The single-command form of if
does output
redirection even if the expression is false and the command is not
executed.
ls-F
includes file identification
characters when sorting filenames and does not handle control characters in
filenames well. It cannot be interrupted.
Command substitution supports multiple commands and conditions,
but not cycles or backward goto
s.
Report bugs at https://bugs.astron.com/ preferably with fixes. If you want to help maintain and test tcsh, add yourself to the mailing list in https://mailman.astron.com/mailman/listinfo/tcsh
November 26, 2024 | Astron 6.24.14 |