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 differ­
       ent interval.

       The  -d  or  --differences flag will highlight the differ­
       ences 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


              watch uname -r

       (Just kidding.)


BUGS

       Upon  terminal  resize,  the  screen will not be correctly
       repainted until the next scheduled update.  All  --differ­
       ences 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.


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