tail 命令的用法

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.

       --retry
          keep trying to open a file even if it is inaccessible when  tail
          starts  or if it becomes inaccessible later; useful when follow-
          ing 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 --fol-
          low=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, other-
       wise, print the last N items in the file.  N may have a multiplier suf-
       fix: 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 descrip-
       tor (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.