in reply to Run and Stop another program in perl

fast:

If you use fork (on an operating system that supports it well), you can set up the I/O streams and fork off the task. Then you'll have the PID (process identifier) for the forked job, and you can kill it when you decide to. Something like:

my $child_PID = fork;
if ($child_PID == 0) {
   # We're in the child process, so redirect I/O handles and run progr
+am...
   close STDOUT;
   open STDOUT, '>', 'foobar.log' or die $!;
   exec 'foobar.exe', 'argument_1', 'second argument', 'etc...';

   die "Couldn't find foobar.exe!";    # should never get here...
}
else {
   # We're in the parent, so wait a few seconds, and kill the child.
   sleep 10;
   kill 9, $child_PID;
}

[download]

Untested code. Testing (and any repairs required) left as an exercise for the reader...

...roboticus

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Re^2: Run and Stop another program in perl
by BrowserUk (Patriarch) on Aug 21, 2010 at 06:18 UTC

    Why would you use forking fork instead of the built-in forking open which works everywhere? :)

[reply]

      BrowserUk:

      I don't normally tie programs together in perl, thus I rarely use fork or open to connect programs together. Hence, I just used the first one I thought of. As I'm a C/C++ programmer, fork naturally came to mind. Perhaps I'll think of open next time... ;^)

      ...roboticus

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Re^2: Run and Stop another program in perl
by JavaFan (Canon) on Aug 21, 2010 at 08:42 UTC
    Funny that both you and BrowserUK decide to kill using SIGKILL. That's not very friendly, and not "the appropriate way" - it doesn't give the program a chance to shutdown gracefully (for instance, if the killed process would be a Perl program, sending it SIGKILL robs the program of its opportunity to run END blocks. Or to call DESTROY. Or to cleanly shut down database connections.). Send it a SIGTERM (often 15, but technically, it's architecture dependent - check $Config::Config{sig_name} if you want to cover portability issues).
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      In my case, there is good reason for that. Did you notice the OPs program name: program.exe?

      On win32, it makes no difference. The following code does kill 15, but notice that it is reported by the terminatng process as sigbreak: 

      Perl> $pid = open CMD, '-|', q[perl.exe -le"$SIG{TERM}=sub{print 'here
+' }; $|++; print ++$i while sleep 1"] or die $!;;

Perl> print scalar <CMD> for 1 .. 10;;
1
2
3
4
5
6
7
8
9
10

Perl> kill 15, $pid;;
Terminating on signal SIGBREAK(21)

      [download]

      The pseudo signals perl provides on win32 are useful, but limited. And bear very little resemblance to POSIX signal handling.

      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.
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