打印文件末尾几行
Usage: 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
-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