#!/usr/bin/perl -w

## Demonstration of chatting with a bash shell.

use strict ;

use IPC::Run qw( start pump finish timeout ) ;

$IPC::Run::debug = 10 ;

my ( $in, $out ) ;

die "usage: runsu <user> <password>" unless @ARGV ;

my $user = @ARGV > 1 ? shift : $ENV{USER} || $ENV{USERNAME} ;
my $passwd = shift ;

my $h = start(
   [qw(su - ), $user], '<pty<', \$in, '>pty>', \$out,
      timeout( 5 ),
) ;

pump $h until $out =~ /^password/im ;

$in = "$passwd\n" ;

## Assume atomic prompt writes
## and that a non-word is the last char in the prompt.
$out = '' ;
pump $h until $out =~ /([^\r\n\w]\s*)(?!\n)$/ ;
my $prompt = $1 ;

print "Detected prompt string = '$prompt'\n" ;

$prompt = quotemeta $prompt ;

for ( qw( ls ps fOoBaR pwd ) ) {
   $in = $_ . "\n" ;
   $out = '' ;
   $h->timeout( 5 ) ; # restart the timout
   pump $h until $out =~ s/\A((?s:.*))(?=^.*?$prompt(?!\n)\Z)//m ;
   print map { "su: $_\n" } split( /\n/m, $1 ) ;
}

$in = "exit\n" ;
finish $h ;