Check if a file is really a file, whether a string contains anything, and whether you can run a program with these vital patterns.

Editor's Note: This article has been updated by its author. Thank you, Pat. Have you ever wanted to change the names of many files at once? Or, have you ever needed to use a default value for a ...

Few aspects of Unix system administration are more intimate than the relationship between the admin and their chosen shell. After all, the shell is the most fundamental interface to the system, the ...