Problem with fork exec kill when redirecting output in perl
- by Edu
I created a script in perl to run programs with a timeout. If the program being executed takes longer then the timeout than the script kills this program and returns the message "TIMEOUT".
The script worked quite well until I decided to redirect the output of the executed program.
When the stdout and stderr are being redirected, the program executed by the script is not being killed because it has a pid different than the one I got from fork.
It seems perl executes a shell that executes my program in the case of redirection.
I would like to have the output redirection but still be able to kill the program in the case of a timeout.
Any ideas on how I could do that?
A simplified code of my script is:
#!/usr/bin/perl
use strict;
use warnings;
use POSIX ":sys_wait_h";
my $timeout = 5;
my $cmd = "very_long_program 1>&2 > out.txt";
my $pid = fork();
if( $pid == 0 )
{
exec($cmd) or print STDERR "Couldn't exec '$cmd': $!";
exit(2);
}
my $time = 0;
my $kid = waitpid($pid, WNOHANG);
while ( $kid == 0 )
{
sleep(1);
$time ++;
$kid = waitpid($pid, WNOHANG);
print "Waited $time sec, result $kid\n";
if ($timeout > 0 && $time > $timeout)
{
print "TIMEOUT!\n";
#Kill process
kill 9, $pid;
exit(3);
}
}
if ( $kid == -1)
{
print "Process did not exist\n";
exit(4);
}
print "Process exited with return code $?\n";
exit($?);
Thanks for any help.
