#!/usr/bin/perl -wT
#

BEGIN {
    delete @ENV{qw(IFS CDPATH ENV BASH_ENV)};
    $ENV{PATH} = "";
}
use strict;

process_ssh_command($ENV{SSH_ORIGINAL_COMMAND});
exit;

sub process_ssh_command {
    my $ssh_command =  shift || '';
    if ( ! $ssh_command ){
        print "Error: You must specify the command to run\n";
        return;
    }
    if ( $ssh_command =~ /^scriptname\s+(options_regex)$/ ){
        my $options= $1 || '';
        # do something if options not set
        chomp(my $stdin = <STDIN>); # if you need it
        # untaint stdin
        system("/path/to/scriptname", $options);
        return;
    }
    print "Error: Unknown command or incorrect format \"$ssh_command\"\n";
    return;
}