A script that starts using
#!/bin/bashoperates in a new invocation of the shell. This shell first executes standard system and user startup scripts. It also inherits exported variables from the parent shell.
Like binary programs, scripts can offer a return value after execution.
Scripts use file tests to examine and check for specific information on files.
Scripts can use command substitution to utilize the result of an external command.
Scripts often send email to notify administrators of errors or status.
Refer to Chapter 13 for details on bash commands.