use IO::Pty;

sub run_in_pty {
    my @cmd = @_;

    my $pty = IO::Pty->new();
    
    my $pid = fork;  die "Couldn' fork: $!" unless defined $pid;
    if ($pid) {  # parent
        $pty->close_slave();
    
    } else {     # child
        my $slv = $pty->slave() or die "Couldn't get slave: $!";
        close $pty;
    
        open STDOUT, ">&".$slv->fileno() or die "Couldn't reopen STDOUT: $!";
        open STDERR, ">&".$slv->fileno() or die "Couldn't reopen STDERR: $!";
    
        exec @cmd;
        die "Couldn't exec(@cmd): $!";
    }

    return join '', (<$pty>);
}

my $cmd = "./bsub";

my $out = run_in_pty($cmd);

print "$cmd: '$out'\n";

##</code><code>##

#!/usr/bin/perl

if (-t STDERR) {  # connected to terminal?
    print STDERR "msg-to-stderr\n";
}
print "msg-to-stdout\n";

##</code><code>##

$ ./bsub >output 2>&1