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WATCH(8)		  BSD 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 util‐
     ity 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, inter‐
	     active 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 over‐
	     flows.  In all cases where a prompt would be displayed, watch
	     will exit.	 The reconnect flags are unaffected by this option.
	     When this flag is used, <control-X> is passed through to the ter‐
	     minal.

     -o	     Reconnect on overflow.  The behavior of watch if the observed tty
	     overflows is similar to the behavior if the observed 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 charac‐
	   ters.

SEE ALSO
     pty(4), sio(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.

BSD			       November 24, 2001			   BSD

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