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

$|=1;

my $pid=open3(\*IN,\*OUT,\*ERR,'/bin/bash -i');

my $cmd = 'builtin alias';

#send cmd to bash
print IN "$cmd\n";

my $result_err = <ERR>;
print "ERR->$result_err\n";

my @aliases;

my $buf;
my $timeout = 1; #after 1 seconds no bash output, script continues

 eval{ local $SIG{ALRM} = sub { goto END }; 
       alarm $timeout;

        while( sysread(OUT, $buf, 512)){
          #print $buf;
          push @aliases,$buf; 
    
    }

             alarm 0;
       };
END:

print "@aliases\n";