Script to Create Directories

Hello,

I need a script to do the following:

1) Read list of users from text file
2) create directories for each user
3) chmod the created directories
4) test for existance of previously created directories

More info:

-Have a file users.txt which the script needs to take in and parse.
-script needs to test if /directory/username already exists
-if not exist, create /directory/username
-chmod /directory/username
-next (till EOF)

Any resources, ideas, or script pieces would be greatly appreciated.

Thanks,