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POHow do I get the PID of the process I start with Perl's system()?
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  1. POHow do I get the PID of the process I start with Perl's system()?
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    copied!<p>I'm writing a Perl script that runs 4 simultaneous, identical processes with different input parameters (see background <a href="https://stackoverflow.com/questions/1961682/using-perl-with-multiple-cores"> here</a> - the rest of my question will make much more sense after reading that).</p> <p>I am making a system() call to a program that generates data (XFOIL, again see above link). My single-core version of this program looks like this:</p> <pre><code>eval{ local $SIG{ALRM} = sub{die "TIMEOUT"}; alarm 250; system("xfoil &lt;command_list &gt;xfoil_output"); alarm 0; }; if ($@){ # read the output log and run timeout stuff... system('killall xfoil') # Kill the hung XFOIL. now it's a zombie. } </code></pre> <p>Essentially, XFOIL should take only about 100 seconds to run - so after 250 seconds the program is hanging (presumably waiting for user input that it's never going to get).</p> <p>The problem now is, if I do a killall in the multi-core version of my program, I'm going to kill 3 other instances of XFOIL, and those processes are generating data. So I need to kill only the hung instance, and this requires getting a PID. </p> <p>I don't know very much about forks and such. From what I can tell so far, I would run an exec('xfoil') inside the child process that I fork. But the PID of the exec() will be different than the PID of the child process (or is it? It's a separate process so I'd assume it is, but again I've no experience with this..), so this still doesn't help when I want to forcefully kill the process since I won't have the PID anyway. How do I go about doing this?</p> <p>Thanks a ton for your help!</p>
 

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