You can use the unfortunately named kill function with a signal value of zero to see if a process is still alive. 

my $pid = 1234;
if( kill 0, $pid ) { 
    # it's alive
} else { 
    # it's dead
}

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In reply to Re^3: how can a perl script determine it's own PID while running by friedo
in thread how can a perl script determine it's own PID while running by Anonymous Monk

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