Submitting password changes to external program

[Dietz]

Fellow Monks!

I'm working on this for over 2 days now to no avail, and I must admit IPC is one of my weakest fields. I have got the task to automate resetting passwords without user input on AIX /w HACMP. Although I'm allowed to test as root user, I'm not allowed to install any modules like Expect.

When I run the external command over the command line, I type in the passwords which get not displayed and all is OK:

# /usr/es/sbin/cluster/sbin/cl_chpasswd -cspoc -f -k testuser
Changing password for "testuser"
testuser's New password: 
Enter the new password again:
# echo $?
0
#

When run by my test script and hitting <Ctrl+C> after the second password display:

# ./test.pl
testuser's New password: testpass
testpass

3004-657 Terminating from signal.

# echo $?
130
#

When run by my test script and typing in the password followed by <ENTER> after second password display:

# ./test.pl
testuser's New password: testpass
testpass

Enter the new password again:
# echo $?
0
#

So I can see the passwords get printed but the external program doesn't get the input.
Any ideas?
Thanks in advance!
Below my test script:

#!/usr/bin/perl
use strict;
use warnings;
$ENV{ODMDIR} = '/etc/objrepos/'; # needed for external program
my $user = 'testuser';
my $password = 'testpass';
my $cmd = "/usr/es/sbin/cluster/sbin/cl_chpasswd -cspoc -f -k $user";
#print $cmd, $/x2; # verified - OK

use IPC::Open2;
my $pid = open2(*Reader, *Writer, $cmd);

# No success with following variations:
#my $pid = open2(*Reader, *Writer, "$cmd </dev/tty");
#my $pid = open2(*Reader, *Writer, "$cmd </dev/tty >/dev/tty");
$| = 1;

# Verify device:
#use POSIX;
#my $tty = POSIX::ctermid();
#print "\nTTY: '$tty'\n\n"; # prints: TTY: '/dev/tty'

local *STDOUT;
open( STDOUT, ">>/dev/tty" );

# wait until external program is ready
sleep 5; 

# Enter password:
#print Writer "$password\n"; # neither displayed nor accepted as input
print "$password\n"; # will be displayed but not accepted as input
sleep 2;

# Repeat password:
#print Writer "$password\n";
print "$password\n";

waitpid $pid, 0;
close Reader;
close Writer;