update awesome widget with mpc current song

update_song_display

#!/usr/bin/env perl 
# François Serman <aifsair@gmail.com>
# 07 nov 2012

# Initial version: updates awesome widget perdiodicaly, or when killed
# via SIGUSR1
#
# Awesome setup:
# mpdbox = widget({ type = "textbox", name = "mpdbox" })
# ...
# mywibox[s].widgets = { 
# {
#    ... ,
#    mpdbox,
#    ...

sub current_song
{
        open (my $mpc, "mpc current 2>&1 |") or die "mpc: $!";
        my $music = <$mpc>;
        close ($mpc);
        $music =~ s@\n@@;
        return 0 if ($music =~ /error/) ;
        $music;
}

sub update_display
{
        my $song = current_song;
        my $full_cmd = sprintf(qq/mpdbox.text = "[ %s ]"/, ($song ? $song : "MPD"));
        open(my $process, "| awesome-client") or die "awesome-client: $!";
        print $process $full_cmd;
        close ($process);
}

$SIG{"USR1"} = \&update_display;

while (1) {
        update_display;
        sleep 2;
}