#! /usr/bin/perl
use FileHandle;
use IPC::Open2;

$pid = open2(*Reader, *Writer, "./progX" );
print Writer "X\n\n1\n2\n\n\n" ;

{ local $/ ;
  $inp = <Reader> ;
}
# or @inp = <Reader>
close Writer, Reader ;

print "Reader: $inp\n" ;