Canceling a Process
You may decide that you shouldn’t have put a process in the background or the process is taking too long to execute. You can cancel a background process if you know its process ID.
Tip
Mac OS X includes a very helpful utility called Force Quit, accessible from the Apple menu, which can be quite useful when applications are stuck or nonresponsive. However, commands entered into the Terminal window can only be cancelled from the command line—they don’t show up in Force Quit. In addition, Force Quit doesn’t show you administrative processes. To stop Unix programs and administrative processes, you must use the command line or the Activity Monitor.
kill
The
kill
command terminates a process. This has the
same result as using the Finder’s Force Quit
command. The kill
command’s
format is:
kill PID(s)
kill
terminates the designated process IDs (shown
under the PID heading in the ps
listing). If you
do not know the process ID, do a ps
first to
display the status of your processes.
In the
following example, the sleep
n
command simply causes a process to
“go to sleep” for
n seconds. We enter two commands,
sleep
and who
, on the same
line, as a background process.
$(sleep 60;who) &
[1] 472 $ ps PID TT STAT TIME COMMAND 347 std S 0:00.36 -bash 472 std S 0:00.00 -bash 473 std S 0:00.01 sleep 60 $kill 473
$ -bash: line 53: 473 Terminated sleep 60 taylor console Sep 24 22:38 taylor ttyp1 Sep 24 22:40 [1]+ Done ( sleep 60; who ) $
We decided that 60 seconds was too long to wait ...
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