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WATCH(1)			 User Commands			      WATCH(1)

       watch - execute a program periodically, showing output fullscreen

       watch [options] command

       watch  runs  command  repeatedly, displaying its	output and errors (the
       first screenfull).  This	allows you to watch the	program	output	change
       over  time.   By	default, command is run	every 2	seconds	and watch will
       run until interrupted.

       -d, --differences [permanent]
	      Highlight	the differences	between	 successive  updates.	Option
	      will  read optional argument that	changes	highlight to be	perma-
	      nent, allowing to	see what has changed at	least once since first

       -n, --interval seconds
	      Specify  update  interval.   The	command	will not allow quicker
	      than 0.1 second interval,	in which the smaller values  are  con-
	      verted. Both '.' and ',' work for	any locales.

       -p, --precise
	      Make watch attempt to run	command	every interval seconds.	Try it
	      with  ntptime  and  notice  how  the  fractional	seconds	 stays
	      (nearly) the same, as opposed to normal mode where they continu-
	      ously increase.

       -t, --no-title
	      Turn off the header showing the interval,	command,  and  current
	      time  at	the top	of the display,	as well	as the following blank

       -b, --beep
	      Beep if command has a non-zero exit.

       -e, --errexit
	      Freeze updates on	command	error, and exit	after a	key press.

       -g, --chgexit
	      Exit when	the output of command changes.

       -c, --color
	      Interpret	ANSI color and style sequences.

       -x, --exec
	      Pass command to exec(2) instead of sh -c which reduces the  need
	      to use extra quoting to get the desired effect.

       -h, --help
	      Display help text	and exit.

       -v, --version
	      Display version information and exit.

	      0	     Success.
	      1	     Various failures.
	      2	     Forking the process to watch failed.
	      3	     Replacing	child  process	stdout	with  write  side pipe
	      4	     Command execution failed.
	      5	     Closing child process write pipe failed.
	      7	     IPC pipe creation failed.
	      8	     Getting  child  process  return  value  with   waitpid(2)
		     failed, or	command	exited up on error.
	      other  The  watch	 will  propagate  command exit status as child
		     exit status.
       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.
       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.

       Combining  Characters  that are supposed	to display on the character at
       the last	column on the screen may display one column early, or they may
       not display at all.

       Combining  Characters  never  count as different	in --differences mode.
       Only the	base character counts.

       Blank lines directly after a line which ends in the last	column do  not

       --precise mode doesn't yet have advanced	temporal distortion technology
       to compensate for a command that	takes more than	 interval  seconds  to
       execute.	  watch	also can get into a state where	it rapid-fires as many
       executions of command as	it can to catch	up from	a previous  executions
       running longer than interval (for example, netstat taking ages on a DNS
       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 "'"'$$'"'"
       To see the effect of precision time keeping, try	adding -p to
	      watch -n 10 sleep	1
       You can watch for your administrator to install the latest kernel with
	      watch uname -r
       (Note that -p isn't guaranteed to work across  reboots,	especially  in
       the face	of ntpdate or other bootup time-changing mechanisms)

procps-ng			  2018-03-03			      WATCH(1)


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