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RedHat 9 (Linux i386) - man page for watch (redhat section 1)

WATCH(1)							Linux User's Manual							  WATCH(1)

NAME
watch - execute a program periodically, showing output fullscreen
SYNOPSIS
watch [-dhv] [-n <seconds>] [--differences[=cumulative]] [--help] [--interval=<seconds>] [--version] <command>
DESCRIPTION
watch runs command repeatedly, displaying its output (the first screenfull). This allows you to watch the program output change over time. By default, the program is run every 2 seconds; use -n or --interval to specify a different interval. The -d or --differences flag will highlight the differences between successive updates. The --cumulative option makes highlighting "sticky", presenting a running display of all positions that have ever changed. watch will run until interrupted.
NOTE
Note that command is given to "sh -c" which means that you may need to use extra quoting to get the desired effect. Note that POSIX option processing is used (i.e., option processing stops at the first non-option argument). This means that flags after command don't get interpreted by watch itself.
EXAMPLES
To watch for mail, you might do watch -n 60 from To watch the contents of a directory change, you could use watch -d ls -l If you're only interested in files owned by user joe, you might use watch -d 'ls -l | fgrep joe' To see the effects of quoting, try these out watch echo $$ watch echo '$$' watch echo "'"'$$'"'" You can watch for your administrator to install the latest kernel with watch uname -r (Just kidding.)
BUGS
Upon terminal resize, the screen will not be correctly repainted until the next scheduled update. All --differences highlighting is lost on that update as well. Non-printing characters are stripped from program output. Use "cat -v" as part of the command pipeline if you want to see them.
AUTHORS
The original watch was written by Tony Rems <rembo@unisoft.com> in 1991, with mods and corrections by Francois Pinard. It was reworked and new features added by Mike Coleman <mkc@acm.org> in 1999. 1999 Apr 3 WATCH(1)