watch

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 screen-
       full).   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)