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Wednesday, 19 July 2017

tail Linux Command

tail

tail [options] [files]

Print the last 10 lines of each named file (or standard input if - is specified) on standard output. If more than one file is specified, the output includes a header at the beginning of each file:

= =>filename<= =

For options that take the number of bytes or lines as an argument, you prepend a plus sign (+) to num to begin printing with the numth item. These options can also specify a block size:

b
512 bytes

k
1 kilobyte

m
1 megabyte

Options

-c num, --bytes num
Print the last num bytes.

-f, --follow[=name|descriptor]
Don't quit at the end of file; "follow" file as it grows and end when the user presses Ctrl-C. Following by file descriptor is the default, so -f, --follow, and --follow=descriptor are equivalent. Use --follow=name to track the actual name of a file even if the file is renamed, as with a rotated logfile.

-F
Identical to --follow=name --retry.

--help
Print a help message and exit.

-n num, --lines=num
Print the last num lines.

--max-unchanged-stats=num
Used with --follow=name to reopen a file whose size hasn't changed after num iterations (default 5), to see if it has been unlinked or renamed (as with rotated logfiles).

--pid=pid
Used with -f to end when process ID pid dies.

-q, --quiet, --silent
Suppress filename headers.

--retry
With -f, keep trying to open a file even if it isn't accessible when tail starts or if it becomes inaccessible later.

-s sec, --sleep-interval=sec
With -f, sleep approximately sec seconds between iterations. Default is 1 second.

-v, --verbose
With multiple files, always output the filename headers.

--version
Print version information and then exit.

Examples

Show the last 20 lines containing instances of .Ah:

grep '\.Ah' file | tail -20

Show the last 10 characters of variable name:

echo "$name" | tail -c

Print the last two blocks of bigfile:

tail -2b bigfile
Annamalai Thangaraj

Annamalai is working as Technical Lead in Leading Telecom company with 5+ years experience in Identity and Access Management , Telecom and Networks, BigData, Java, Spring, Struts, Hibernate, AngularJS, and Enterprise Web Application Development.

Website: Java Tutorials Corner

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Item Reviewed: tail Linux Command Rating: 5 Reviewed By: Annamalai Thangaraj