use strict;
use warnings;

my $cmd_1 = "perl hello.pl";

open (CMD, "$cmd_1 2>&1|") or warn ("!!! Can't run program: $!\n");

while (my $line = <CMD>)
{
	print $line;
        #if ($line =~ m/^xyz/)
        #{
        #   # do some string manipulation and write it to another file
	#}
}
close CMD;