Shell scripting concepts covered in this lesson:

• Reasons to create functions

• DRY vs WET programming concepts:

  • DRY: Don’t Repeat Yourself

  • WET: Write Everything Twice, We Enjoy Typing, Waste Everyone’s Time

• Defining functions

• Calling functions

• Sending messages to the syslog subsystem with the logger command.

• Where to place functions in your script.

• Variable scope and the local shell builtin.

• Passing in data to a function.

• Making variables read-only with the readonly shell builtin.

• How to backup files before you change them.

• Exit status of functions and the return command.