sub get_acpi_info {
open P, "-|", "/usr/bin/acpi -a -b";
my $acpi_string = join '', <P>;
close P;
my ($charge) = ($acpi_string =~ m{(\d+)%});
my ($remaining) = ($acpi_string =~ m{(\d\d:\d\d:\d\d)});
$acpi_string =~ /on-line/ ? "$charge% online"
: "$charge% $remaining";
}