# starting the application
my $handle = start \@args, \$in, \$out, \$err;

##</code><code>##

my ($in, $out, $err);
for($in,$out,$err) { $_ = \my $x }

# starting the application
my $handle = start \@args, $in, $out, $err;

# wait until prompted for input
pump $handle until $$out =~ /Login:/;        # note the dereferencing - $$out
$in .= "Boris\n";

# wait until prompted for password
pump $handle until $$out =~ /Password:/;

# and so on ...

# store them
$client_descr->{"Handle"} = $handle;
$client_descr->{"In"}     = $in;
$client_descr->{"Out"}    = $out;
$client_descr->{"Err"}    = $err;

##</code><code>##

$in .= "new data\n";
pump $handle until $$out =~ /data arrived:/; # note the dereferencing - $$out
print $$out;

##</code><code>##

$client_descr->{"Handle"} = $handle;
$client_descr->{"In"}     = \$in;
$client_descr->{"Out"}    = \$out;
$client_descr->{"Err"}    = \$err;

# later ...
my ($handle, $in, $out) = ($client_descr->{"Handle"}, $client_descr->{"In"}, $client_descr->{"Out"});
$in .= "new data\n";
pump $handle until $$out =~ /data arrived:/; # note the dereferencing - $$out
print $$out;