Have a look at IPC::Run for a robust implementation of this, or for simple uses that don't require pty emulation and you don't need to capture the output, open will do what you want. Here's a barebones look at both:

    use 5.010;
    use autodie;

    # With basic open()
    open my $sort, '|-', 'sort -n';
    printf $sort "%d\n", rand 100 for 1..10;
    close $sort;
    
    # With IPC::Run
    use IPC::Run qw/start finish pump/;
    print "IPC::Run output:\n";
    my $r = start [ 'perl' ], \my $in, \my $out, \my $err
        or die "Can't start: $!";
    $in .= 'print "Hello, world!\n";';
    finish $r;
    say $out;
    die 'ERROR: $err' if length $err;
[download]

Output:

13
14
34
37
44
63
83
86
90
95
IPC::Run output:
Hello, world!
[download]

See perlipc for general information: there are several ways to do that.