my %commands = (
        cmd1 => \&do_cmd1,
        cmd2 => \&do_cmd2,
        ....
    );

##</code><code>##

    ## untested, just something I thought up right now
    chomp( $input = <STDIN> );
    my( $cmd, @args ) = split( /\s+/, $input );

    if( defined( $commands{ $cmd } ) ) {
        $command{ $cmd }->( @args );
    }