These docs are under active development and cover the v0.20 Kobicha security model.
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tail

tail prints the end of a file — by default, the last 10 lines.

tail [options] [file...]

$ tail server.log

It is the counterpart of head: the quick way to see the most recent lines of a file. With no file, tail reads standard input.

Choosing how much

Option Effect
-n, --lines=NUM Print the last NUM lines instead of 10.
-c, --bytes=NUM Print the last NUM bytes instead of counting lines.

If NUM is given a leading +, the meaning flips: tail prints everything from line NUM onward.

$ tail -n +20 report.txt    # from line 20 to the end

Following a growing file

tail's most useful trick is -f. Instead of printing the end and exiting, it stays running and prints new lines as they are appended — the standard way to watch a log file live.

Option Effect
-f, --follow Keep the file open and print new data as it is added.
-F Follow the file by name, and keep retrying if it is missing. Equivalent to --follow=name --retry. This survives log rotation — when the file is replaced, -F picks up the new one.
--retry Keep trying to open a file that is not yet accessible.
--pid=PID While following, stop once process PID exits.
-s, --sleep-interval=N Wait N seconds between checks of the file.

Press Ctrl-C to stop a tail -f.

Headers for multiple files

As with head, when given more than one file tail prints a header before each.

Option Effect
-q, --quiet Never print the file-name headers.
-v, --verbose Always print the header, even for a single file.

Other options

Option Effect
-z, --zero-terminated Treat the NUL character as the line delimiter instead of newline.

Exit status

Code Meaning
0 Success.
1 A file could not be read.

See also