Book: LPI Linux Certification in a Nutshell Section: Chapter 22. Exam 102 Review Questions and Exercises
### 22.5 Shells, Scripting, Programming, and Compiling (Topic 1.9) #### 22.5.1 Review Questions Name the two major shell variants found on Unix and Linux systems. What characteristic of a bash variable changes when the variable is exported? Describe the concept of shell aliases. When is a shell function more suitable than a shell alias? Describe the function of /etc/profile. What must the author of a new script file do to the file's mode? How does the shell determine what interpreter to execute when starting a script? How can a shell script use return values of the commands it executes? #### 22.5.2 Exercises Using bash, enter the export command and the set command. Which set of variables is a subset of the other? What is the difference between the variables reported by export and those reported by set? Finally, enter which export. Where is the export command located? Examine /etc/profile. How is the default umask set? What customizations are done in the file for system users? Create a simple bash script using the `#!/bin/bash` syntax, set the executable mode bits, and execute the shell. If it runs correctly, add errors to see the diagnostic messages. Have the script report both exported and nonexported variables. Verify that the nonexported variables do not survive the startup of the new shell.