watch

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



NAME
       watch - execute a program periodically, showing output fullscreen

SYNOPSIS
       watch  [-dhvt]  [-n  <seconds>]	[--differences[=cumulative]] [--help]
       [--interval=<seconds>] [--no-title] [--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.	 The -t or --no-title option turns off the header showing the
       interval, command, and current time at the top of the display, as well
       as the following blank line.

       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)