in reply to Capture PID from child process on Windows.

The problem you are encountering is that fork creates a pseudo-process (a thread) and the "pid" returned is a (negative) threadid, not a process id.

The simplest way is to use the piped open, which spawns a real process and returns a real pid: 

perl> $pid = open KID, 'perl -e"1 while sleep 1 |' or die $!;;
perl> kill 21, $pid;;
Terminating on signal SIGBREAK(21)
perl> close KID;;

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