Thank's for the help. What I meant by it doesn't work, is there was something worng with the syntax and it was generating an error when I ran it. I would like to run the script with an argument being the file system. That part I can do, by saving the contents of ARGV[0] into the variable $filesystem. I would then like to check that the file system is served by the host that the program is running on. If it isn't report an error. for example: $host = `hostname`; $filesystem = $ARGV[0]; Now I would like to check those details against my hash. That is the part that is confusing me. One host could have multiple filesystems. How would I go about looking up whether the file system belongs to the host, or not? Thanks