#!/usr/bin/perl

use strict;
use warnings;

my @cmd_list = ( 'echo 1', 'echo 2', 'echo 3', 'echo 4' );

$|++;  # turn off buffering

my $shpid = open( my $sh, '|-', '/bin/bash' )
    or die "Can't open a shell process: $!\n";

for my $cmd ( @cmd_list ) {
    print $sh "$cmd\n";
}
print $sh "exit\n";
close $sh;
waitpid( $shpid, 0 );

print "Shell's all done.  Moving right along...\n";