Unix tail command
You could see last part of the file using tail command. It prints last 10 line of input files. If you give multiple file name it then it precedes with set of output with header giving file name.
- Syntax:
tail [option]… [File]…
- Options help:
To see what are all options are available for tail command please use below:
$ tail –help
javahonk$ tail --help
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.
-c, --bytes=K output the last K bytes; alternatively, use -c +K
to output bytes starting with the Kth of each file
-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=K output the last K lines, instead of the last 10;
or use -n +K to output lines starting with the Kth
--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).
With inotify, this option is rarely useful.
--pid=PID with -f, terminate after process ID, PID dies
-q, --quiet, --silent never output headers giving file names
--retry keep trying to open a file even when it is or
becomes inaccessible; useful when following by
name, i.e., with --follow=name
-s, --sleep-interval=N with -f, sleep for approximately N seconds
(default 1.0) between iterations.
With inotify and --pid=P, check process P at
least once every N seconds.
-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 K (the number of bytes or lines) is a `+',
print beginning with the Kth item from the start of each file, otherwise,
print the last K items in the file. K may have a multiplier suffix:
b 512, kB 1000, K 1024, MB 1000*1000, M 1024*1024,
GB 1000*1000*1000, G 1024*1024*1024, and so on for T, P, E, Z, Y.
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 in a way that accommodates renaming, removal and creation.
Report tail bugs to bug-coreutils@gnu.org
GNU coreutils home page: <http://www.gnu.org/software/coreutils/>
General help using GNU software: <http://www.gnu.org/gethelp/>
Report tail translation bugs to <http://translationproject.org/team/>
For complete documentation, run: info coreutils 'tail invocation'Examples:
- tail test.txt – Output last 10 lines of test.txt
- tail -f text.txt – Output last 10 lines of test.txt and watch text.txt file for any updates. If any updates happens to the file it ouputs new line that are added (Important command to check log files)
- tail test.txt -n 50 – Output last 50 lines of test.txt
- tail -f text.txt | grep Java Honk – Very useful command if you want to monitor log file in real time. Here tail monitor the text.txt file and pipes final ten lines and any new lines added. Grep command reads output and prints only lines which contains word Java Honk
- For more information on Unix command please visit Wikipedia
