Usage: /usr/bin/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
      --help
         display this help and exit
      --version
         output version information and exit

Non-seekable input is buffered to $TMPDIR, defaulting to /tmp.

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/>
Full documentation <https://www.gnu.org/software/coreutils/tac>
or available locally via: info '(coreutils) tac invocation'