Thursday, March 27, 2014

$! and $$ System variables(7.14.1)


$! and $$ system variables:

                  The special variables $! holds the PID value of the last background job,and the special variables $$ holds the PID value of the current shell.The last background job can be killed using the command $kill $!. The current shell can be killed using the sure kill command $kill-9$$.

       It should be noted that one can kill only his or her own processes.One of the best ways to know which processes one owns is to issue the ps command piped to grep containing his or her username.

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