tail - output the last part of files


tail [-c [+]N[bkm]] [-n [+]N] [-fqv] [--bytes=[+]N[bkm]] [--lines=[+]N] [--follow] [--quiet] [--silent] [--verbose] [--help] [--version] [file...] tail [{-,+}Nbcfklmqv] [file...]


This manual page documents the GNU version of tail. tail prints the last part (10 lines by default) of each given file; it reads from standard input if no files are given or when a filename of `-' is encountered. If more than one file is given, it prints a header consisting of the file's name enclosed in `==>' and `<==' before the output for each file.

The GNU tail can output any amount of data, unlike the Unix version, which uses a fixed size buffer. It has no -r option (print in reverse). Reversing a file is really a different job from printing the end of a file; the BSD tail can only reverse files that are at most as large as its buffer, which is typically 32k. A reliable and more versatile way to reverse files is the GNU tac command.


tail accepts two option formats: the new one, in which numbers are arguments to the option letters, and the old one, in which a `+' or `-' and optional number precede any option letters.

If a number (`N') starts with a `+', tail begins printing with the Nth item from the start of each file, instead of from the end.

-c N, --bytes N
Tail by N bytes. N is a nonzero integer, optionally followed by one of the following characters to specify a different unit.

512-byte blocks.

1-kilobyte blocks.

1-megabyte blocks.

-f, --follow
Loop forever trying to read more characters at the end of the file, on the assumption that the file is growing. Ignored if reading from a pipe. If more than one file is given, tail prints a header whenever it gets output from a different file, to indicate which file that output is from.
-l, -n N, --lines N
Tail by N lines. -l is only recognized using the old option format.
-q, --quiet, --silent
Never print filename headers.
-v, --verbose
Always print filename headers.
Print a usage message and exit with a status code indicating success.
Print version information on standard output then exit.