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

     watch -- snoop on another tty line

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

     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-

     -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

     -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/.

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

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

     pty(4), sio(4), snp(4), kldload(8)

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

     Ugen J.S. Antsilevich <ugenATNetVision.il>

     The watch utility first appeared in FreeBSD 2.1.

BSD                            November 24, 2001                           BSD