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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] [--ver-
       sion] <command>

DESCRIPTION
       watch runs command repeatedly, displaying its output (the first screenfull).  This allows you to watch the pro-
       gram  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 --dif-
       ferences 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 <remboATunisoft.com> in 1991, with mods and corrections by Francois
       Pinard.  It was reworked and new features added by Mike Coleman <mkcATacm.org> in 1999.



                                  1999 Apr 3                          WATCH(1)