use IPC::Open2 'open2';
sub backtick {
        my ($in, @cmd) = @_;
        # $in is a string to pass to STDIN,
        # @cmd is a command to run
        my $pid = open2(my $stdout, my $stdin, @cmd);
        # first we write to stdin
        print {$stdin} $in if defined $in; close $stdin;
        # then we read the response
        my $out = do { local $/; <$stdout> };
        # then we wait for the program to die
        waitpid $pid, 0;
        # beware of deadlocks!
        die "$cmd[0] returned $? / error $!\n" if $?;
        return $out;
}