watch (Unix)

watch is a command-line tool, part of the Linux procps and procps-ng packages, that runs the specified command repeatedly and displays the results on standard output so you can watch it change over time. By default, the command is run every two seconds, although this is adjustable with the -n secs argument. Since the command is passed to sh -c, you may need to encase it in quotes for it to run correctly.

Syntax

watch [options] command [command options]

Example

watch "ps -e | grep php"

This will generate a list of processes every two seconds, filter for all lines that contain the word "php", and display the results on the screen. The output might look something like this:

Every 2s: ps -e | grep php                             Tue Jan 30 14:56:33 2007

reconst  30028  0.0  0.0  7044 2596 ?        S    Jan23   0:00 vim -r core/html_api.php
cinonet  28009  0.0  0.2 20708 11064 ?       SN   Jan25   0:30 php5.cgi
donoiz   23810  0.0  0.2 22740 10996 ?       SN   Jan27   0:30 php.cgi 43/pdf

The watch command is useful for viewing changes over time, like repeatedly running the ls -l command to watch a file's size change, or running ps as in the above example to monitor certain processes continuously.

Arguments

-d – Highlights differences between iterations
-h – Displays a help message, then exits
-n secs – Specifies the interval between executions of the command in seconds
-t – Tells watch not to display the header
-v – Prints version information, then exits

External links

watch(1): execute a program periodically, showing output fullscreen – Linux User Commands Manual
procps
procps-ng

Unix command-line interface programs and shell builtins

File system	cat chmod chown chgrp cksum cmp cp dd du df file fsck fuser ln ls mkdir mount mv pax pwd rm rmdir split tee touch type umask

Processes	at bg chroot cron fg kill killall nice pgrep pkill ps pstree time top

User environment	clear env exit finger history logname mesg passwd su sudo uptime talk tput uname w wall who whoami write

Text processing	awk banner basename comm csplit cut diff dirname ed ex fmt fold head iconv join less more nl paste printf sed sort spell strings tail tr uniq vi wc xargs yes

Shell builtins	alias cd echo test unset wait

Networking	dig host ifconfig inetd netcat netstat nslookup ping rdate rlogin route ssh traceroute

Searching	find grep locate whatis whereis

Documentation	apropos help man

Miscellaneous	bc dc cal expr lp od sleep true and false

List of Unix commands

This article is issued from Wikipedia - version of the 6/14/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.

watch (Unix)

Syntax

Example

Arguments

See also

External links