Summery
一定時間毎にコマンドを実行できる。Construction
$ watch [option] [command]
Option
-n : 実行間隔の秒数 -d : 変化部分を強調して表示
Sample
# 3秒ごとにファイルの増減を監視
watch -n 3 "ls | wc -l"
Discription
NAME
watch - execute a program periodically, showing output fullscreen
SYNOPSIS
watch [-dhvt] [-n <seconds>] [--differences[=cumulative]] [--help] [--interval=</seconds><seconds>]
[--no-title] [--version] <command />
DESCRIPTION
watch runs 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 -n or
--interval to specify a different interval.
The -d or --differences flag will highlight the differences between successive updates. The --cumu-
lative option makes highlighting "sticky", presenting a running display of all positions that have
ever changed. The -t or --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.
watch will run until interrupted.
NOTE
Note that command is given to "sh -c" which means that you may need to use extra quoting to get the
desired effect.
Note that 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.
EXAMPLES
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 "’"’$$’"’"
You can watch for your administrator to install the latest kernel with
watch uname -r
(Just kidding.)
BUGS
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.
AUTHORS
The original 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.
1999 Apr 3 WATCH(1)
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