#!/usr/bin/perl

print '',( `acpi` =~ /(\d+)%/ )[ 0 ] // '??', "%";

##</code><code>##

#!/usr/bin/perl
#battery.pl

use strict;
use warnings;
use 5.012;

my $battery_charge;

$battery_charge = `acpi`;

if($battery_charge =~ /\d{2}%/ )
{

        print "Battery: $&\n";
}