NAME

tr - translate or delete characters

SYNOPSIS

tr [OPTION]... STRING1 [STRING2]

DESCRIPTION

Translate, squeeze, and/or delete characters from standard input, writing to standard output. STRING1 and STRING2 specify arrays of characters ARRAY1 and ARRAY2 that control the action.

-c, -C, --complement: use the complement of ARRAY1
-d, --delete: delete characters in ARRAY1, do not translate
-s, --squeeze-repeats: replace each sequence of a repeated character that is listed in the last specified ARRAY, with a single occurrence of that character
-t, --truncate-set1: first truncate ARRAY1 to length of ARRAY2
--help: display this help and exit
--version: output version information and exit

ARRAYs are specified as strings of characters. Most represent themselves. Interpreted sequences are:

\NNN: character with octal value NNN (1 to 3 octal digits)
\\: backslash
\a: audible BEL
\b: backspace
\f: form feed
\n: new line
\r: return
\t: horizontal tab
\v: vertical tab
CHAR1-CHAR2: all characters from CHAR1 to CHAR2 in ascending order
[CHAR*]: in ARRAY2, copies of CHAR until length of ARRAY1
[CHAR*REPEAT]: REPEAT copies of CHAR, REPEAT octal if starting with 0
[:alnum:]: all letters and digits
[:alpha:]: all letters
[:blank:]: all horizontal whitespace
[:cntrl:]: all control characters
[:digit:]: all digits
[:graph:]: all printable characters, not including space
[:lower:]: all lower case letters
[:print:]: all printable characters, including space
[:punct:]: all punctuation characters
[:space:]: all horizontal or vertical whitespace
[:upper:]: all upper case letters
[:xdigit:]: all hexadecimal digits
[=CHAR=]: all characters which are equivalent to CHAR

Translation occurs if -d is not given and both STRING1 and STRING2 appear. -t is only significant when translating. ARRAY2 is extended to length of ARRAY1 by repeating its last character as necessary. Excess characters of ARRAY2 are ignored. Character classes expand in unspecified order; while translating, '[:lower:]' and '[:upper:]' may be used in pairs to specify case conversion. Squeezing occurs after translation or deletion. Arguments like '[...]' should be quoted, to avoid potential shell globbing.

BUGS

Full support is available only for safe single-byte locales, in which every possible input byte represents a single character. The C locale is safe in GNU systems, so you can avoid this issue in the shell by running LC_ALL=C tr instead of plain tr.

AUTHOR

Written by Jim Meyering.

REPORTING BUGS

Report bugs to: bug-coreutils@gnu.org
GNU coreutils home page: https://www.gnu.org/software/coreutils/
General help using GNU software: https://www.gnu.org/gethelp/
Report any translation bugs to https://translationproject.org/team/

COPYRIGHT

Copyright © 2026 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later https://gnu.org/licenses/gpl.html.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.