Shell Scripting

🔹 1. Introduction to Shell & Bash

• What is a Shell?

• Types of Shells (Bash, Zsh, Sh, etc.)

• Why use Shell Scripting?

• Running commands interactively vs. scripting

• Bash vs other shells

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🔹 2. Basic Terminal Commands

• ls, cd, pwd, mkdir, rm, cp, mv

• Viewing file contents: cat, less, more, head, tail

• File permissions: chmod, chown, umask

• Working with text: grep, awk, sed

• Finding files: find, locate

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🔹 3. Writing Your First Shell Script

• Creating a .sh file

• Adding shebang (#!/bin/bash)

• Making the script executable (chmod +x)

• Running the script (./script.sh)

• Best practices for writing scripts

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🔹 4. Variables and Data Types

• Declaring and using variables

• Reading user input (read)

• Command substitution (var=$(command))

• Constants and readonly variables

• Environment variables

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🔹 5. Operators in Shell

• Arithmetic operators

• Relational operators

• Logical operators

• Assignment operators

• File test operators (-e, -f, -d, etc.)

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🔹 6. Conditional Statements

• if, else, elif

• Nested if statements

• case statements

• Exit statuses ($?)

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🔹 7. Loops in Shell

• for loops

• while loops

• until loops

• Using break and continue

• Looping through files and arguments

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🔹 8. Functions in Shell

• Declaring functions

• Calling functions

• Passing arguments to functions

• Returning values

• Using functions for modular scripting

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🔹 9. Input and Output

• echo, printf

• Reading from files

• Redirecting input/output (>, >>, <)

• Piping (|)

• Here Documents (<<)

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🔹 10. Command Line Arguments

• $0, $1, $2, … $n

• $@, $#, $*

• Handling optional and required arguments

• Argument validation

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🔹 11. File and Directory Handling

• Creating, reading, writing files

• Directory traversal with loops

• Logging and error handling

• Temporary files and clean-up scripts

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🔹 12. String and Text Processing

• String manipulation

• Pattern matching and regular expressions

• Using cut, tr, awk, and sed for text processing

• Parsing log files and reports

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🔹 13. Error Handling and Debugging

• Checking command exit status

• Using trap for cleanup

• Debugging with bash -x

• Creating log files for errors

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🔹 14. Scheduling with Cron Jobs

• Introduction to cron

• Writing and managing crontab entries

• Time-based automation

• Logging and testing cron scripts

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🔹 15. Working with Processes and System Info

• Checking system resources (top, htop, free, df)

• Process management (ps, kill, nice, jobs, bg, fg)

• Automation for backups, monitoring, and cleanup

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🔹 16. Advanced Shell Scripting Topics

• Arrays and associative arrays

• File locking

• Script portability and compatibility

• Security practices in shell scripting

• Interactive scripts with menus (using select)

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🔹 17. Real-world Script Examples

• Automated system backup

• Disk usage report

• Log file analysis

• File renaming or conversion

• User account management

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🔹 18. Shell Scripting Projects

• Build your own command-line utility

• Create an installer script

• Automate software update checker

• Develop a daily report generator

• Build a basic system monitor tool