#!/usr/bin/perl
use v5.12;
use warnings;

chdir("/");
for my $backup_dir (glob("/backup/*")) {
    next unless -f "$backup_dir/active";
    say STDERR "unmounting $backup_dir";
    system("/bin/umount", $backup_dir);
    if ($backup_dir =~ m{(luks-[^/]+)}) {
        say STDERR "closing $1";
        system("/sbin/cryptsetup", "close", $1)
    }
}