Does anyone know of an image thumbnail generator? It's running on a 
server, so I do not have many libraries installed.

What I need it to do is to read in an image file and generate a 
thumbnail image file in the same format. It needs to take all arguments 
on the command line because it will be embedded in a script.

Something like this..
$ thumbs file.jpg > thumbnail.jpg

Anyone know of a package like this?

Thanks in advance.