# simplest way, but ignores error handing
my $pid;
if($pid = fork() == 0)
    {                                                       
      exec("other_tk_script");
    }                                          
 
##</code><code>##

#!/usr/bin/perl
my $kidpid;

if ( !defined( $kidpid = fork() ) ) {
    #fork returned undef, so failed
    die "Cannot fork: $!";
}
elsif ( $kidpid == 0 ) {
    # fork returned 0, so this branch is child
    exec("xterm -e top");
    # if exec fails, fall through to the next statement
    die "can't exec : $!";
}
else {

    # fork returned 0 nor undef
    # so this branch is parent
    sleep(5);
    my $result = kill "TERM", $kidpid;
    print "Killed child process $kidpid (result $result)\n";
    sleep(5);

}