I know this isn't your question, but you can accomplish the same task with Net::Telnet. Here's a script:

#!/usr/bin/perl

use Net::Telnet;

my $dow = `date '+%w' --date '1 days ago'`;
my $router = "IP_OF_ROUTER";
my $user = "username";
my $pass = "password";
my $enable = "enable_password";
my $tftp_server = "IP_OF_SERVER";
my $t = new Net::Telnet(Timeout => 10);

$t->open( $router );
$t->waitfor( '/Username:/' );
$t->print( "$user" );
sleep 2;
$t->waitfor( '/Password:/' );
$t->print( "$pass" );
sleep 2;
$t->print( "enable" );
$t->waitfor( '/Password:/' );
$t->print( "$enable" );
sleep 2;
$t->print( "copy startup-config tftp" );
sleep 2;
$t->print( "$tftp_server" );
sleep 2;
$t->print( "router.$dow" );
sleep 3;
$t->print( "quit" );

exit( 0 );
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