*.[hc] This gives a list of filenames that end in either .h or .c.
a?? This gives you all three-letter filenames that begin with a.
[^a]?? This gives you all three-letter filenames that do not begin with a.
a* This gives you every filename that starts with a, regardless of how many letters it has.
7. More on Files
In section 5.2 on page [*], we covered moving and renaming files with mv, copying them with cp, removing them with rm, removing directories with rmdir, and creating directories with mkdir. This chapter will cover some more aspects of working with files.
Permissions
GNU and Unix systems are set up to allow many people to use the same computer, while keeping certain files private or keeping certain people from modifying certain files. You can verify this for yourself. Log in as yourself, i.e. NOT as root.
whoami
This verifies that you are not root. Then enter the following command: