.TH TEX 1 "24 January 2026" "Web2C 2026"
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.\"=====================================================================
.SH NAME
tex, initex \- text formatting and typesetting
.SH SYNOPSIS
.B tex
.RI [ options ]
.RI [ \fB&\fPformat ]
\h'.25' [ \fIfile\fP [ \fImore-input\fP ] \h'.5'|\h'.5' [ \fB\e\fP\fImore-input\fP ]
.\"=====================================================================
.SH DESCRIPTION
Run the \*(TX typesetter on
.IR file [.tex],
usually creating
.IR file.dvi .
If the file argument has no extension, ".tex" will be appended to it. 
.PP
The normal usage is to run
.IP
tex paper
.PP
to process \fIpaper.tex\fP with \*(TX.
The name
.I paper
will be the so-called "jobname", and is used in forming
output filenames.
If \*(TX doesn't get a filename in the first line, the jobname is
.IR texput .
When looking for a file, \*(TX looks for the name with and without the
default extension
.RI ( .tex )
appended, unless the name already contains that extension.  If
.I paper
is the jobname,
a log of error messages, with rather more detail than normally appears
on the screen, will be written to
.IR paper.log ,
and the output file will be
.IR paper.dvi .
The \fB--jobname\fP option sets the jobname explicitly.
.PP
\*(TX
formats the interspersed text and commands contained in the input
and outputs a so-called
.I DVI
file, which is short for
.IR "DeV\h'.02'ice Independent" .
DVI files are a device-independent binary representation of the pages in
the output document. They can be displayed online (e.g.,
.BR xdvi (1)),
translated to PDF
.RB ( dvipdfmx (1)),
PostScript
.RB ( dvips (1)),
or otherwise manipulated. Other engines
.RB ( pdftex (1),
.BR luatex (1)),
descendants of original \*(TX, can output PDF directly.
.PP
\*(TX's capabilities and language are described in many places (see the
references), including Donald Knuth's original book,
.IR "The \*(OXbook" .
\*(TX is normally used with a large body of precompiled macros, called a
format. Knuth's original format is named \fIplain\fP. Other formats,
notably \fBlatex\fP(1), are much larger, but still implemented entirely
as \*(TX macros.
.PP
.B Command line processing
.PP
To process the command line, after first reading any \fIoption\fR(s)
(listed below), if the first non-option argument does not begin with an
escape character (normally a backslash), \*(TX internally prepends
\fB\einput\fP to the non-option arguments. Whether the \fB\einput\fP was
prepended or not, \*(TX then processes the text as normal \*(TX input,
including macro expansion.
.PP
With no non-option arguments, \*(TX gives you a \fB**\fP interactive
prompt; whatever text you enter is processed in exactly the same way as
non-option command line arguments.
.PP
Examples:
.TP
.B tex foo
executes "\einput foo".
.TP
.B tex foo bar
executes "\einput foo bar", which inputs
\fIfoo.tex\fP and then typesets the string "bar".
.TP
.B tex \e\eend
executes \eend; here the double backslash is one common way of escaping
the backslash for the shell. \*(TX must see only one backslash.
.PP
To reiterate, the text of an input filename, as well as any text
following a filename, is subject to \*(TX's macro expansion. As a
result, a ~ character is normally not usable within a filename, since ~
is conventionally defined to be an active character that expands into
several primitive tokens, which can't be part of a filename. You can
usually use \estring~ to get a literal ~ character. More on input
filenames: https://tug.org/texinfohtml/web2c.html#Input-filenames
.PP
.B Format (.fmt) selection
.PP
With an argument 
\fB&\fIformat\fR, \*(TX reads the set of precompiled commands
contained in the (binary) file
.IR format .fmt
instead of the default tex.fmt (searched for using the TEXFORMATS path; see
environment section below). This is sometimes more convenient than the
.B -fmt
.I format
option, which is equivalent.
.PP
The \*(TX implementation in \*(TX Live (a.k.a. Web2C) looks at
its command line to find the name it was invoked as. When called as
.BR initex
(or when the
.B -ini
option is given, which is equivalent) it can be used to precompile
macros into a
.I .fmt
file.  When called as
.B virtex
it will use the
.I plain
format.  Nowadays, if either or both of the executables
.B initex
and
.B virtex
exist, they are symbolic links to the
.B tex
executable; the
.B virtex
symlink is not made by default in \*(TX Live.
.PP
When invoked as any other name, \*(TX will use that name as
the name of the format to use.  Most notably, when invoked as
.B tex
the format file
.I tex.fmt
is read, which is identical to the
.I plain
format.  The commands defined by the
.I plain
format are described in Appendix\~B of
.IR "The \*(OXbook" ,
among other places (see references below). The other \*(TX engines
follow the same convention; for example, the
.B latex
command is a symlink to the
.B pdftex
binary, and reads \fIlatex.fmt\fP.
.PP
This implementation of \*(TX can look in the first line of the file
.I paper.tex
to see if it begins with the magic two-character sequence
.IR %& .
If the first line begins with
.BI %& format
.BI -translate-file \ tcxname
then \*(TX will use the named format and (if specified) translation table
.I tcxname
to process the source file.  Either the format name or the
.B -translate-file
specification may be omitted, but not both.  This overrides the
format selection based on the name by which the program is invoked.
The
.B -parse-first-line
option or the
.I parse_first_line
configuration variable controls whether this behavior is enabled.  It is
disabled for the original \*(TX, and enabled for all other engines.
.PP
.B Input encodings
.PP
\*(TX, predating Unicode as it does, reads input byte by byte, and has
no native recognition for UTF-8 or any other encoding. This is also the
case for pdf\*(TX. However, to a large extent, UTF-8 can be parsed at
the \*(TX macro level, and packages have been developed for this. For
native recognition of Unicode, the engines
.BR luatex (1)
and
.BR xetex (1)
are available, with corresponding formats.
.PP
.B Error handling
.PP
\*(TX's error messages can be rather unfortunately cryptic. As general
advice, sometimes only the first error matters, so it's worth trying to
fix that first. Cutting down the input file can be helpful if mysteries
remain. For more advice, including on a few specific problems:
https://texfaq.org/index#errors
.PP
A convenient file in most distributions is
.IR null.tex ,
containing nothing.
When \*(TX can't find a file it thinks you want to input, it keeps
asking you for another filename; responding "null" gets you out
of the loop if you don't want to input anything.  You can also type your
EOF character (usually control-D).
.PP
When \*(TX reports an error, by default it puts you into an interactive
dialog with a ? prompt. Responding with another ? shows you
the available responses, for example, \fIx\fP quits immediately. The
.I e
response to \*(TX's error prompt causes the system default editor to
start up at the current line of the current file. The environment
variable TEXEDIT can be used to change the editor used. It may contain a
string with "%s" indicating where the filename goes and "%d" indicating
where the decimal line number (if any) goes. For example, a TEXEDIT
string specifying emacs to be run can be set like this (in Bourne shell
syntax):
.IP
TEXEDIT="emacs +%d %s"; export TEXEDIT
.PP
To debug problems with finding files, see the \fB--kpathsea-debug\fP
option below.
.\"=====================================================================
.SH OPTIONS
\*(TX (in \*(TX Live and Web2C) understands the following command line
options. Most of these options are also supported by the derived
engines.
.PP
Options can be started with either - or --; in this and other
documentation, we use "-" and "--" interchangeably. Options can be
separated from their values with either an = character or whitespace.
Put filenames or other non-options that start with a dash after an
option --. All the programs in the \*(TX family (and many non-\*(TX
programs; this command-line parsing comes originally from the GNU
getopt_long_only(3) library function) follow these conventions.
.PP
In \*(TX and the other engines, all options must precede any non-option
arguments, due to the peculiarities of \*(TX's first-line parsing
described above. For the \*(TX utilities, options and non-options can be
given in any order.
.TP
.B -help
Print help message and exit.
.TP
.BI -cnf-line \ string
Parse
.I string
as a
.I texmf.cnf
configuration line.  See the Kpathsea manual.
.TP
.B -enc
Enable the enc\*(TX extensions.  This option is only effective in
combination with
.BR -ini .
For documentation of the enc\*(TX extensions see
http://www.olsak.net/enctex.html.
.TP
.B -[no-]file-line-error
Print error messages in the form
.I file:line:error
which is similar to the way many other compilers format them. By
default, or with \fB-no-\fP, \*(TX's default error format is used,
usually starting with an ! character.
.TP
.B -file-line-error-style
This is the old name of the
.B -file-line-error
option.
.TP
.BI -fmt \ format
Use
.I format
as the name of the format to be used, instead of the name by which
\*(TX was called or a
.I %&
line. (See above and below for more on formats.)
.TP
.B -halt-on-error
Exit with an error code when an error is encountered during processing.
.TP
.B -ini
Start in
.I INI
mode, which is used to dump formats.  The
.I INI
mode can be used for typesetting, but no format is preloaded, and
basic initializations like setting catcodes may be required.
.TP
.BI -interaction \ mode
Sets the interaction mode.  The mode can be either
.IR batchmode ,
.IR nonstopmode ,
.IR scrollmode ,
and
.IR errorstopmode .
The meaning of these modes is the same as that of the corresponding
\ecommands.
.TP
.B -ipc
Send DVI output to a socket as well as the usual output file.  Whether
this option is available is the choice of the installer.
.TP
.B -ipc-start
As
.BR -ipc ,
and starts the server at the other end as well.  Whether this option
is available is the choice of the installer.
.TP
.BI -jobname \ name
Use
.I name
for the job name, instead of deriving it from the name of the input file.
(See above.)
.TP
.BI -kpathsea-debug \ bitmask
Sets path searching debugging flags according to the bitmask.  See the
.I Kpathsea
manual for details: https://tug.org/texinfohtml/kpathsea.html#Debugging
.TP
.BI -[no-]mktex \ fmt
Enable (disable)
.RI mktex fmt ,
where
.I fmt
must be
.IF fmt ,
.IR tex ,
or
.IR tfm .
See the Kpathsea manual: https://tug.org/texinfohtml/kpathsea.html#mktex-scripts
.TP
.B -mltex
Enable ML\*(TX (Multi-lingual \*(TX) extensions.  Only effective in
combination with
.BR -ini .
More info: https://tug.org/texinfohtml/web2c.html#MLTeX
.TP
.BI -output-comment \ string
Use
.I string
for the
.I DVI
file comment instead of the date.
.TP
.BI -output-directory \ directory
Write output files in
.I directory
instead of the current directory.  Look up input files in
.I directory
first, then along the normal search path. See also the description below
of the TEXMFOUTPUT environment variable.
.TP
.B -[no-]parse-first-line
Enable (or disable) checking the first line of the main input file
for
.I %&
and, if so, parsing it to look for a format name or a
.B -translate-file
option.
.TP
.BI -progname \ name
Pretend to be program \fIname\fP for purposes of Kpathsea lookups. This
affects both the format used and the search paths.
.TP
.B -recorder
Enable the filename recorder. This outputs a machine-readable trace of
all files opened for input and output in a file with the usual jobname
and extension
.IR .fls .
.TP
.B -[no-]shell-escape
Allow (or disallow) documents to execute arbitrary shell commands via the
.BI \ewrite18{ command }
construct. This feature is normally restricted for security reasons to a
very few known-safe programs. You should use this option, which enables
execution of any command at all, only for trusted documents. More on
shell escapes: https://tug.org/texinfohtml/web2c.html#Shell-escapes
.TP
.B -src-specials
Insert source specials into the dvi file. This is used for
.BR synctex (1).
In editors that support Sync\*(TX, you can click in the output window
and get back to the corresponding location in the source.
.TP
.BI -src-specials \ where
Insert source specials in certain places of the
.I DVI
file;
.I where
is a comma-separated value list:
.IR cr ,
.IR display ,
.IR hbox ,
.IR math ,
.IR par ,
.IR parent ,
or
.IR vbox .
.TP
.BI -translate-file \ tcxname
Use the
translation table in the file
.I tcxname
to set the mapping of input characters and
re-mapping of output characters.
.TP
.BI -default-translate-file \ tcxname
Like
.B -translate-file
except that a
.I %&
line can override this setting.
.TP
.B -8bit
Make all characters printable by default.
.TP
.B -version
Print version information and exit.
.\"=====================================================================
.SH ENVIRONMENT
Numerous environment variables can be used to find files. A few are
mentioned here, but see the Kpathsea(rch) library documentation (e.g.,
https://tug.org/texinfohtml/kpathsea.html#TeX-support) for a more
comprehensive list, and how they are used. The
.BR kpsewhich (1)
utility can be used to query the values of the variables. In Kpathsea
specifications, "//" means to search subdirectories recursively.
.PP
Every variable setting in \fItexmf.cnf\fR can be overridden by the
environment variable of the same (or associated) name, as explained
tersely at the top of \fItexmf.cnf\fR, and more completely in the
Kpathsea documentation.
.TP
.B TEXMFOUTPUT
Normally, \*(TX puts its output files in the current directory.  If
any output file cannot be opened there, it tries to open it in the
directory specified in the environment variable TEXMFOUTPUT.
There is no default value for that variable.  For example, if you say
.I tex paper
and the current directory is not writable, if TEXMFOUTPUT has
the value
.IR /tmp ,
\*(TX attempts to create
.I /tmp/paper.log
(and
.IR /tmp/paper.dvi ,
if any output is produced.)  TEXMFOUTPUT is also checked for input
files, as \*(TX often generates files that need to be subsequently
read; for input, no suffixes (such as ".tex") are added;
the input name is simply checked as given.
.PP
If the \fB-output-directory\fP option is given, \*(TX sets TEXMFOUTPUT
in the environment to its value, so that programs invoked by \*(TX have
it available.
.PP
More on output file location:
https://tug.org/texinfohtml/web2c.html#Output-file-location
.TP
.B TEXINPUTS
Search path for
.I \einput
and
.I \eopenin
files. By default, this starts with . (a period, meaning the current
directory as usual), so that user files are found before system files.
An empty path component will be replaced with the paths defined in the
.I texmf.cnf
file.  For example, set TEXINPUTS to ".:/home/user/tex:" to prepend the
current directory and "/home/user/tex" to the standard search path.
.TP
.B TEXMFDOTDIR
In \*(TX Live's \fItexmf.cnf\fP, TEXINPUTS and other paths don't start
literally with ".", but rather with $TEXMFDOTDIR, which in turn
defaults to ".". This indirection makes it easy to, for example, search
the current directory and all its subdirectories for everything: set
TEXMFDOTDIR to ".//".
.TP
.B TEXFORMATS
Search path for format files (\fI.fmt\fP). They are typically stored
under the TEXMFSYSVAR directory. You can find the exact location
of \fItex.fmt\fP (for example) with this kpsewhich invocation:
.br
kpsewhich -engine=/ -all tex.fmt
.TP
.B TEXPOOL
Search path for \*(TX's internal strings (\fI.pool\fP); this is only
relevant for original \*(TX; the extended engines all have the strings
compiled into the binary.
.TP
.B TFMFONTS
Search path for font metric
.RI ( .tfm )
files.
.TP
.B TEXEDIT
Command template for switching to editor (see above).  The default, usually
.BR vi ,
is set when \*(TX is compiled.
.\"=====================================================================
.SH FILES
The locations of the files mentioned below varies from system to
system.  Use the
.B kpsewhich
utility to find their locations.
.TP
.I texmf.cnf
Configuration file.  This contains definitions of search paths as well
as other configuration parameters like
.IR parse_first_line .
.TP
.I tex.pool
Text file containing \*(TX's internal strings.
.TP
.I *.tfm
Metric files for \*(TX's fonts.
.TP
.I *.fmt
Predigested \*(TX format (.\|fmt) files.
.TP
.I $TEXMFMAIN/tex/plain/base/plain.tex
The basic macro package described in \fIThe \*(OXbook\fP.
.TP
.I $TEXMFMAIN/tex/plain/config/tex.ini
The driver file that builds the plain format file, \fItex.fmt\fP, in
\*(TX Live.
.\"=====================================================================
.SH BUGS
This version of \*(TX implements a number of extensions, which
technically conflict with the definition of original \*(TX (although
almost never make a difference in practice). When such extensions are
enabled, the banner printed when \*(TX starts is changed to print "TeXk"
instead of "TeX".
.PP
This version of \*(TX fails to trap arithmetic overflow when dimensions
are added or subtracted. Cases where this occurs are rare, but when it
does the program may crash, and/or the generated DVI file will be
invalid. Patches to catch such overflow cases would be welcome.
.PP
Knuth still accepts new bug reports for \*(TX, but only reviews them
every several years. They are vetted in advance by a small group of
experienced volunteers. For a list of submitted reports and other
information: https://tug.org/texmfbug.
.PP
Naturally, bugs in engines other than original \*(TX should be directed
to their respective mailing lists and maintainers.
.\"=====================================================================
.SH "SEE ALSO"
.BR mf (1),
.BR pdftex (1),
.BR latex (1),
.BR luatex (1),
and plenty more.
.br
Donald E. Knuth,
.IR "The \*(OXbook" ,
Addison-Wesley.
.br
Leslie Lamport,
.IR "\*(OL: A Document Preparation System" ,
Addison-Wesley.
.PP
Some free documentation on the \*(TX language:
.br
Petr Olsak, \*(TX in a Nutshell:
https://ctan.org/pkg/tex-nutshell
.br
Plain \*(TX documentation topic on CTAN:
https://ctan.org/topic/tut-plaintex
.br
Victor Eijkhout,
.IR "\*(OX By Topic" ,
A \*(TXnician's reference:
https://www.eijkhout.net/tex/tex-by-topic.html
.br
Paul W. Abrahams, Kathryn Hargreaves, Karl Berry,
.IR "\*(OX for the Impatient" ,
on \*(TX, plain \*(TX, and
.BR eplain (1);
available in French and Chinese translations:
https://ctan.org/pkg/impatient
.PP
Some online information:
.br
Getting Started with TeX, LaTeX, and friends,
a short web page with selected resources:
https://tug.org/begin
.br
David Bausum, \*(TX primitive control sequences:
https://tug.org/utilities/plain/cseq.html
.br
Levels of \*(TX, briefly describing the various engines and formats:
https://tug.org/levels
.br
\*(TX Live web pages:
https://tug.org/texlive
.br
Web2C Texinfo manual and web page:
https://tug.org/web2c
.br
Kpathsea Texinfo manual and web page:
https://tug.org/kpathsea
.br
Sources for the \*(TX-world literate programs, as pdf:
https://ctan.org/pkg/knuth-pdf
.br
.I TUGboat
(the journal of the \*(TX Users Group; submissions welcome):
https://tug.org/TUGboat
.PP
If you find \*(TX useful, please consider joining or supporting the
\*(TX Users Group, or another user group in your area:
.br
https://tug.org
.br
https://tug.org/usergroups.html
.\"=====================================================================
.SH TRIVIA
\*(TX, pronounced properly, rhymes with ``blecchhh''.  The proper
spelling in typewriter-like fonts is ``TeX'' and not ``TEX'' or ``tex''.
.\"=====================================================================
.SH AUTHORS
\*(TX was created by Donald E. Knuth, who implemented it using his WEB
system for Pascal programs. It was ported to Unix at Stanford by Howard
Trickey, and at Cornell by Pavel Curtis. The version now included in
\*(TX Live, the current Unix \*(TX distribution, is generated by the
Web2C system originally written by Tomas Rokicki and Tim Morgan.
.PP
Bug reports in original \*(TX (exceedingly rare): https://tug.org/texmfbug
.br
Public mailing list for implementation questions and reports:
https://lists.tug.org/tex-k
.br
Public discussion list for \*(TX Live:
https://lists.tug.org/tex-live
.br
Public discussion list for all things \*(TX (and \*(LX):
https://lists.tug.org/texhax