If you are on Win32:

 "system(1, @args)" spawns an external process and immediately 
returns its process designator, without waiting for it to terminate.
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Update: I forgot to include that this only works in combination with fork. For a nice PM node discussing how to use fork and exec together to get back control immediately after starting a child process see Fork and exec. This chapter that O'Reilly has posted from one of their books, has some good examples: see 10.10 Forking/Spawning Child Processes

ELISHEVA: I think you have made a mistake. exec() on it's own will replace the currently running perl process with the new program, so a sucessfull call to exec will never return.

Perhaps you are thinking of a fork/exec or one of the many inter process comumnication methods described in perlipc.

To answer the original question, it depened on what shayak means by 'stops responding' Assuming that he can deduce that, then I would say the simplest method would be to start the process with open or fork/exec eg:

my $child_pid = open $handle, '-|', '/path/to/program' or die "Error s
+tarting program $!";

# Some time later the program stops responding
kill($child_pid);
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or:

my $child_pid = fork();
if( 0 == $child_pid )
{
  # Child
  exec '/path/to/program';
  die "error starting program $!";
}

# Some time later the program stops responding
kill($child_pid);
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Exec didnt work..

Exec should give you back control. If it didn't we're going to have to brainstorm together and that is quite hard to do with something as vague as "didn't work".

Could you be more precise about what you mean by "didn't work". Didn't work as in "didn't run"? Didn't work as in "didn't get back control"? If you know your script started, how did you know that? What did you see/look for? If you didn't get back control, how did you know that?

At this point, I think it might help if you reduced your code to the smallest possible number of lines that illustrate the problem and then post those lines (preferrably by updating your original post so everyone can see it). How exactly did you make the call to exec? What went before? What came after?

If you are lucky, getting things down to the smallest number of lines that illustrate the problem (and I do mean smallest), might actually tell you why it didn't work. Otherwise, we'll all be in a better position to brainstorm with you.

You can do this in perl with fork()+exec(), either directly or through a module like the aforementioned Proc::Background or Parallel::ForkManager. Or you can let the shell do the same trick with backgrounding the process:

perl -e 'system("emacs &"); print "yes";'
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