88 lines
2.3 KiB
Groff
88 lines
2.3 KiB
Groff
.TH WATCH 1 "1999 Apr 3" " " "Linux User's Manual"
|
|
.SH NAME
|
|
watch \- execute a program periodically, showing output fullscreen
|
|
.SH SYNOPSIS
|
|
.B watch
|
|
.I [\-dhvt] [\-n <seconds>] [\-\-differences[=cumulative]] [\-\-help] [\-\-interval=<seconds>] [\-\-no\-title] [\-\-version] <command>
|
|
.SH DESCRIPTION
|
|
.BR watch
|
|
runs
|
|
.I 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
|
|
.I -n
|
|
or
|
|
.I --interval
|
|
to specify a different interval.
|
|
.PP
|
|
The
|
|
.I -d
|
|
or
|
|
.I --differences
|
|
flag will highlight the differences between successive updates. The
|
|
.I --cumulative
|
|
option makes highlighting "sticky", presenting a running display of all
|
|
positions that have ever changed. The
|
|
.I -t
|
|
or
|
|
.I --no-title
|
|
option turns off the header showing the interval, command, and current
|
|
time at the top of the display, as well as the following blank line.
|
|
.PP
|
|
.BR watch
|
|
will run until interrupted.
|
|
.SH NOTE
|
|
Note that
|
|
.I command
|
|
is given to "sh -c"
|
|
which means that you may need to use extra quoting to get the desired effect.
|
|
.PP
|
|
Note that POSIX option processing is used (i.e., option processing stops at
|
|
the first non-option argument). This means that flags after
|
|
.I command
|
|
don't get interpreted by
|
|
.BR watch
|
|
itself.
|
|
.SH EXAMPLES
|
|
.PP
|
|
To watch for mail, you might do
|
|
.IP
|
|
watch \-n 60 from
|
|
.PP
|
|
To watch the contents of a directory change, you could use
|
|
.IP
|
|
watch \-d ls \-l
|
|
.PP
|
|
If you're only interested in files owned by user joe, you might use
|
|
.IP
|
|
watch \-d 'ls \-l | fgrep joe'
|
|
.PP
|
|
To see the effects of quoting, try these out
|
|
.IP
|
|
watch echo $$
|
|
.IP
|
|
watch echo '$$'
|
|
.IP
|
|
watch echo "'"'$$'"'"
|
|
.PP
|
|
You can watch for your administrator to install the latest kernel with
|
|
.IP
|
|
watch uname -r
|
|
.PP
|
|
(Just kidding.)
|
|
.SH BUGS
|
|
Upon terminal resize, the screen will not be correctly repainted until the
|
|
next scheduled update. All
|
|
.I --differences
|
|
highlighting is lost on that update as well.
|
|
.PP
|
|
Non-printing characters are stripped from program output. Use "cat -v" as
|
|
part of the command pipeline if you want to see them.
|
|
.SH AUTHORS
|
|
The original
|
|
.B 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.
|