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)