Lab Activity
Module 5: Shells and Shell Scripting
Learn to manage shell environments, create and execute scripts with variables, conditions, loops, and functions, and customize your shell workflow.
Overview
In this lab, you'll explore shell environments, variables, scripting fundamentals, and command customization. You'll learn how shell scripts automate tasks by storing command sequences in files, using control flow like if statements and loops. The lab covers writing simple scripts, handling variables, positional parameters, and making scripts executable. You'll also customize your shell environment with aliases and functions, enabling more efficient command-line workflows and automation for system administration.
Learning Outcomes
- Create and navigate workspace directories for shell scripting practice.
- Display and understand shell environment variables like
$SHELL,$USER,$HOME, and$PATH. - Create, export, and unset shell and environment variables.
- Understand and customize the
PATHenvironment variable to include additional directories. - Create, make executable, and run simple shell scripts with shebang lines.
- Use positional parameters and special variables to pass and process command-line arguments.
- Write shell scripts with conditional logic using if-then-else structures.
- Implement loops in shell scripts to iterate through files and other items.
- Create aliases and functions to customize the shell environment and reuse code.
- View and manage command history and history settings.
- Locate shell executables and check shell versions.
Key Concepts
- Shell Environment Variables: Variables that define the working environment of the shell, such as
$SHELL,$USER, and$PATH. - Local and Exported Variables: Local variables exist only in the current shell, while exported variables are passed to child processes.
- Shell Scripting Fundamentals: Writing scripts with interpreters specified by shebang, using variables, conditionals, loops, and command-line arguments.
- Command Aliases and Functions: Tools to simplify command usage and build reusable code blocks within the shell session.
- Command History: Shell feature that stores previously executed commands, configurable with variables like
HISTSIZE. - Script Executability: Using
chmod +xto grant execution permissions for running shell scripts. - Positional Parameters: Special variables like
$1,$2, etc., used in scripts to handle input arguments.
Why It Matters
- Mastering shell environments and variables enables effective session customization and script portability.
- Shell scripting automates repetitive tasks, enables complex workflows, and enhances system administration efficiency.
- Learning conditionals and loops empowers you to write intelligent and dynamic scripts.
- Aliases and functions streamline your command line workflow, making repetitive operations simpler and faster.