linux--watch命令使用

linux--watch命令使用 1.watch命令簡介  www.2cto.com  watch [options] commandThe watch program executes a given command at regular inter-vals; the default is every two seconds. The command is passed to the shell (so be sure to quote or escape any special characters), and the results are displayed in a full-screen mode, so you can observe the output conveniently and see what has changed. For example, 每隔一段時間重複運行一個命令，預設間隔時間是2秒。要啟動並執行命令直接傳給shell（注意引用和轉義特殊字元）。結果會展示為全螢幕模式，這樣你可以很方便的觀察改變。例如: watch -n 60 date executes the date command once a minute, sort of a poor man’s clock. Type ^C to exit.執行date命令每分鐘一次，輸入^C  退出。  www.2cto.com  2.Useful options常用選項 -n seconds Set the time between executions, in seconds.    設定已耗用時間間隔，以秒為單位-d Highlight differences in the output, to emphasize what has changed from one execution to the next.    高亮輸出不同，強調兩次執行的不同。 3.watch 手冊NAME       watch - execute a program periodically, showing output fullscreen       watch - 定期執行程式，輸出全屏 SYNOPSIS       watch  [-dhvt]  [-n  <seconds>]  [--differences[=cumulative]]  [--help]       [--interval=<seconds>] [--no-title] [--version] <command> DESCRIPTION       watch runs command repeatedly, displaying its output (the first screen-full).   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.       監視重複運行命令，展示輸出（全屏）。讓你監視程式輸出變化。預設程式2s運行一次；使用-n或--interval 指定不同的間隔時間        The  -d  or  --differences  flag will highlight the differences between successive  updates.   The  --differences[=cumulative]  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.       -d 或 --differences 會高亮顯示新內容。--cumulative 選項讓高亮保持，展示運行中所有的修改的內容。 -t 或 --no-title 選項關閉頭部展示，只展示空白行。        watch will run until interrupted.       watch會一直運行，知道中斷。 NOTE       Note that command is given to "sh -c" which means that you may need  to use extra quoting to get the desired effect.       注意，命令"sh -c" 你需要應用起來才能達到預期的效果。        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.       注意，使用POSIX選項（選項會停在第一個非選項參數）意味著你不能在命令後再設定間隔。  www.2cto.com   EXAMPLES       To watch for mail, you might do       查看郵件 watch -n 60 from       To watch the contents of a directory change, you could use       查看目錄變化： watch -d ls -l       If you’re only interested in files owned by user joe, you might use       想找joe使用者的檔案，是下面的命令 watch -d ’ls -l | fgrep joe’       To see the effects of quoting, try these out       看引號的使用      watch echo $$     watch echo ’$$’     watch echo "’"’$$’"’"結束