The subroutine as your have coded it doesn't actually have a meaningful return value. The problem is that the "system" command does not capure the output text of the command. Perl has a different operator for that:

sub ctrl {
   return qx/xmmsctrl print %T/;
}

my $ctrl = ctrl();
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The qx operation could also be written using backticks:

sub ctrl {
   return `xmmsctrl print %T`;
}
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