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WATCH(8)		    System Manager's Manual		      WATCH(8)

NAME
       watch --	snoop on another tty line

SYNOPSIS
       watch [-cinotW] [-f snpdev] [tty]

DESCRIPTION
       The  watch utility allows the user to examine all data coming through a
       specified tty using the snp(4) device.  If the  snp(4)  device  is  not
       available,  watch  will	attempt	 to  load the module (snp).  The watch
       utility writes to standard output.

       The options are as follows:

       -c	  Reconnect on close.  If the tty observed by watch is closed,
		  automatically	reattach to the	same tty.  If this  option  is
		  not  specified,  watch  will request a new tty if running in
		  interactive mode or exit if running  without	a  controlling
		  tty.

       -f snpdev  If  this  option  is specified, watch	will use snpdev	as the
		  snp(4) device.  Without this option, watch will  attempt  to
		  find the next	available snp(4) device.

       -i	  Force	 interactive  mode.   Interactive mode is a default if
		  watch	is started from	a tty.	If output is redirected	 to  a
		  file,	 interactive mode can still be requested by specifying
		  this option.

       -n	  Disable the ability to switch	the watched tty	interactively.
		  This disables	both change requests made with <control-X>  as
		  well	as  automatic prompting	when the current tty is	closed
		  or overflows.	 In all	cases where a  prompt  would  be  dis-
		  played, watch	will exit.  The	reconnect flags	are unaffected
		  by  this  option.   When  this  flag is used,	<control-X> is
		  passed through to the	terminal.

       -o	  Reconnect on overflow.  The behavior of  watch  if  the  ob-
		  served  tty  overflows is similar to the behavior if the ob-
		  served tty is	closed.	 For more info see snp(4).

       -t	  Print	the date and time when observation of a	given  tty  is
		  started.

       -W	  Allow	write access to	observed tty.

       tty	  Tty may be specified as a tty-style device, such as a	pseudo
		  tty device, a	virtual	console, or a serial line, etc.	 Names
		  may be preceded by /dev/.

OPERATION
       While  running  in interactive mode, all	user input is discarded	except
       for:

       <control-G>
	     Exit watch.
       <control-W>
	     Clear screen.
       <control-X>
	     Change attached tty, unless this feature is  disabled,  in	 which
	     case  control-X  is  passed to the	terminal as with other control
	     characters.

SEE ALSO
       pty(4), snp(4), kldload(8)

HISTORY
       The watch utility first appeared	in FreeBSD 2.1.

AUTHORS
       Ugen J.S. Antsilevich <ugen@NetVision.net.il>

BUGS
       No terminal emulation is	performed.  All	user output is reproduced  as-
       is.

FreeBSD	15.0		       November	24, 2001		      WATCH(8)

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<https://man.freebsd.org/cgi/man.cgi?query=watch&manpath=FreeBSD+15.0-RELEASE+and+Ports>

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