tac — concatenate and print files in reverse


tac [OPTION...] [FILE...]


Write each FILE to standard output, last line first. With no FILE, or when FILE is −, read standard input.

Mandatory arguments to long options are mandatory for short options too.

−b, −−before

attach the separator before instead of after

−r, −−regex

interpret the separator as a regular expression

−s, −−separator=STRING

use STRING as the separator instead of newline


display this help and exit


output version information and exit

GNU coreutils online help: <> Report tac translation bugs to <>


Written by Jay Lepreau and David MacKenzie.



The full documentation for tac is maintained as a Texinfo manual. If the info and tac programs are properly installed at your site, the command

  • info coreutils 'tac invocation'

should give you access to the complete manual.


Copyright © 2014 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <>.

This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.