im currently working on a bash script to backup my ubuntu servers web pages and mysql db. Im using a zip drive cause it just happens to have one and figure would be fun to try to do it..(Dont have alot of scriptting experience) Ive gotten my script to check if the zip is mounted, if not mounts it. Then I even have it strip the % of the disk in use from df. Now my question is:

Is there a way in linux to create a completely useless file at a specific size?

I am looking for an easy way to test my script with the amount of disk in use without having to copy random files over to this disk. would like to just be able to create a file that uses say 90% of it. A LONG time ago I had a program for DOS that did this Resize.exe i think it was called but long since lost that file. Thanks!