GNU/Linux man pages
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GNU/Linux |
CentOS 5.3 |
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tail(1) |
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tail − output the last part of files
tail [OPTION]... [FILE]...
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.
−−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
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−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
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−−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 tail’ed 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.
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.
Written by Paul Rubin, David MacKenzie, Ian Lance Taylor, and Jim Meyering.
Report bugs to <bug−coreutils@gnu.org>.
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.
The full documentation for tail is maintained as a Texinfo manual. If the info and tail programs are properly installed at your site, the command
info tail
should give you access to the complete manual.
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tail(1) | |