See fork. If you need to run a separate program in this separate process, you can also look at exec. If you want to fork an external program and have a pipe to either its standard input or output, then open can take care of this for you (see perlopentut for a tutorial on that).

I don't need access to it's standard input or input, and exec won't work because I still want the main program to be able to continue doing other stuff.

Then you probably want to use fork and exec together like this:

# we're in the "main program"...

my $child = fork();
die "fork failed: $!" unless ( defined( $child ));
if ( $child == 0 ) {
    # the child process does this:
    exec( 'other_program', @args );
}
# the parent now goes on to do whatever follows, while the child is ru
+nning...
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Som good documentations are perldoc perlipc and the info documentation of gnu libc.

$SIG{CHLD}='IGNORE';    #Make sure there are no zombies after children
+ die.
my $pid=fork;
print "Failed to fork: $!\n" unless(defined($pid));
unless ($pid)
{
        #Child process here. 
}
#Parent process continues.
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