how to TIMEOUT a system()?

[Weirong Zhu]

A beginner question!
I have a piece of code

#!/usr/bin/perl -w

print "$$ \n";


eval{
local $SIG{ALRM} = sub { die "Timeout Alarm" };
alarm 5;
$rt = system("/home/user/tmp/long");
alarm 0;
};
if ($@ = ~/Timeout Alarm/) {
print "**** Time Out\n";
}

blahblah......

----------------------------

when it finishes, the child process invoked by system() does not
terminated. But I want to kill it when it's timed out. How to do this?
The reason that I want to use the system(), because I want to get the
return value when it's not timed out.

 

[Ben Morrow]

eval{
local $SIG{ALRM} = sub { die "Timeout Alarm" };
alarm 5;
$rt = system("/home/user/tmp/long");
alarm 0;
};
if ($@ = ~/Timeout Alarm/) {
print "**** Time Out\n";
}

when it finishes, the child process invoked by system() does not
terminated. But I want to kill it when it's timed out. How to do this?
The reason that I want to use the system(), because I want to get the
return value when it's not timed out.

You want to use the technique in 'Safe Pipe Opens' in perlipc to get
the pid of the child process, and then kill it in the signal handler.

Ben