#!/usr/bin/perl
use warnings;
use strict;
use IPC::Open3;

my $pid = open3(\*WRITE, \*READ, \*ERROR,"your_command");
if( ! $pid ){ die "$!\n";}

#my $pid = open3(\*WRITE, \*READ,0,"your_command");
#if \*ERROR is false, STDERR is sent to STDOUT 

#while(1){

print "Enter a string to evaluate\n";
chomp(my $query = <STDIN>);

#send query to command
print WRITE "$query\n";

#give small time to output
select(undef,undef,undef,.5); #half second delay

#get the answer from command
chomp(my $answer = <READ>);
print "$query = $answer\n";
# you may need something with sysread, if <READ> hangs
# my $bytes_read = sysread(READ, my $buf, 1024);
# print "$query = $buf\n";

#get the error from command
chomp(my $error = <ERROR>);
print "$query error = $error\n";

#}
waitpid($pid, 1);
# It is important to waitpid on your child process,  
# otherwise zombies could be created.