tail - Unix, Linux Command
NAME
tail - output the last part of files
SYNOPSIS
tail [OPTION]... [FILE]...
DESCRIPTION
Print the last 10 lines of each FILE to standard output.
With more than one FILE, precede each with a header giving the file name.
With no FILE, or when FILE is -, read standard input.
Mandatory arguments to long options are mandatory for short options too.
Tag | Description |
--retry
|
keep trying to open a file even if it is
inaccessible when tail starts or if it becomes
inaccessible later; useful when following by name,
i.e., with --follow=name
|
-c, --bytes=N
| |
output the last N bytes
|
-f, --follow[={name|descriptor}]
| |
output appended data as the file grows;
-f, --follow, and --follow=descriptor are
equivalent
|
-F
|
same as --follow=name --retry
|
-n, --lines=N
| |
output the last N lines, instead of the last 10
|
--max-unchanged-stats=N
| |
with --follow=name, reopen a FILE which has not
changed size after N (default 5) iterations
to see if it has been unlinked or renamed
(this is the usual case of rotated log files)
|
--pid=PID
| |
with -f, terminate after process ID, PID dies
|
-q, --quiet, --silent
| |
never output headers giving file names
|
-s, --sleep-interval=S
| |
with -f, sleep for approximately S seconds
(default 1.0) between iterations.
|
-v, --verbose
| |
always output headers giving file names
|
--help
|
display this help and exit
|
--version
| |
output version information and exit
|
If the first character of N (the number of bytes or lines) is a +,
print beginning with the Nth item from the start of each file, otherwise,
print the last N items in the file. N may have a multiplier suffix:
b 512, k 1024, m 1024*1024.
With --follow (-f), tail defaults to following the file descriptor, which
means that even if a tailed file is renamed, tail will continue to track
its end. This default behavior is not desirable when you really want to
track the actual name of the file, not the file descriptor (e.g., log
rotation). Use --follow=name in that case. That causes tail to track the
named file by reopening it periodically to see if it has been removed and
recreated by some other program.
_POSIX2_VERSION COMPATIBILITY ISSUES:
On older systems, the leading - can be replaced by + in
the obsolete option syntax with the same meaning as in counts, and
obsolete usage overrides normal usage when the two conflict.
This obsolete behavior can be enabled or disabled with the
_POSIX2_VERSION environment variable, but portable scripts should
avoid commands whose behavior depends on this variable.
For example, use tail -- - main.c or tail main.c rather than
the ambiguous tail - main.c, tail -c4 or tail -c 10
4 rather than the ambiguous tail -c 4, and tail ./+4
or tail -n +4 rather than the ambiguous tail +4.
You can work around those compatibility problems by setting
_POSIX2_VERSION=199209 in your environment.
AUTHOR
Written by Paul Rubin, David MacKenzie, Ian Lance Taylor, and Jim Meyering.
REPORTING BUGS
Report bugs to <bug-coreutils@gnu.org>.
COPYRIGHT
Copyright © 2006 Free Software Foundation, Inc.
This is free software. You may redistribute copies of it under the terms of
the GNU General Public License <http://www.gnu.org/licenses/gpl.html>.
There is NO WARRANTY, to the extent permitted by law.
SEE ALSO
tail is maintained as a Texinfo manual. If the
info and
tail programs are properly installed at your site, the command
should give you access to the complete manual.
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