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✏️ Editing: 5.B.top

#!/usr/bin/perl
#	Here we set manual_stty on the process so we can do things like
#hit ^Z to stop it instead of the ^Z going to the process on the other machine.
#	This is to say, normally when you interact with a process STDIN is
#put in raw mode so everything you type talks to the process at the other end.
#	Picture this. When you telnet somewhere and start a process (top
#for example) you are talking to telnet in raw mode. If you press ^Z it
#goes through telnet to the shell on the remote machine and the process
#at the other end is stopped. Here we're going to make it so raw mode is
#never set and when you press ^Z or ^C it will stop/interrupt Expect.
#	Also briefly demonstrated is the use of Expect::interconnect(),
#a more general/versatile alternative to interact.

use Expect;

# Debugging anyone?
# $Expect::Log_Stdout=1;
# $Expect::Exp_Internal=1;
# $Expect::Debug=1;

$RSH='/usr/bin/ssh';

$host_to_login_to=shift(@ARGV);

print "Enter password: ";
$|=1;
# First we have to initialize STDIN in to an expect object.
$stdin=Expect->exp_init(\*STDIN);
# Now turn off echoing
$stdin->exp_stty('-echo');
# The easy way to do this is:
#$password=<STDIN>;
#chop $password;
# The somewhat harder way is to use $stdin->expect. This would look like:
#
 ($match_num,$error,$match,$before,$after)=$stdin->expect(undef,"\n");
 $password = $before;
# Turn echo back on
$stdin->exp_stty('echo');
# print that newline that wasn't echoed
print "\n";

#$Expect::Exp_Internal=1;

$rsh=Expect->spawn($RSH,$host_to_login_to);

# Look for a password prompt.
$rsh->expect(30,'-re','word:\s$')||(die"Never got password prompt\n");

print $rsh "$password\r";

# Look for a prompt. Prompt can be # $ > or ] followed by a whitespace.
$prompt  = '[\]\$\>\#]\s$';

# Note the use of -re
$rsh->expect(30,'-re',$prompt)||(die "Never got prompt on host\n");

# Start top
print $rsh "exec top\r";

# We already have an inited handle for STDIN above which we can use.
# We don't just do $rsh->interact because it will go monkeying
# with tty settings by default (set it raw).
$stdin->manual_stty(1);
# Instead we use interconnect directly. 
# The trick here is to make sure:
# 1. Everything listening to a handle is added to its
# listen group.
# 2. Only what you want is jabbering at STDOUT.
# 
# In this case only $rsh will talk to STDOUT so we don't have to 
# change any log_stdout() settings.
$stdin->set_group($rsh);
Expect::interconnect($stdin,$rsh);

MR SKB