Shell Scripting Learning Project

A comprehensive collection of bash scripts demonstrating fundamental to intermediate shell scripting concepts, from basic scripts to production-ready maintenance automation.

1. Shell Scripting Basics

Scripts covering foundational bash concepts.

hello.sh

• Purpose: First shell script introduction
• Concepts: Shebang line, echo command, script execution
• Key Learning: Scripts require shebang (#!/bin/bash) and executable permissions

variables.sh

• Purpose: Demonstrate variable usage and quoting differences
• Concepts: Variable assignment, single vs. double quotes, variable expansion
• Key Learning: Double quotes allow variable expansion; single quotes treat content literally

greet.sh

• Purpose: User input handling with the read command
• Concepts: read command, user prompts, variable interpolation
• Key Learning: Collect user input and use it in output messages

check_number.sh

• Purpose: Conditional logic with if-else statements
• Concepts: Numeric comparisons (-gt, -lt), if-elif-else structures
• Key Learning: Evaluate numbers and branch logic based on conditions

file_check.sh

• Purpose: File existence validation
• Concepts: File test operators (-f), conditional execution
• Key Learning: Check if files exist before processing them

server_check.sh

• Purpose: Service status monitoring with user interaction
• Concepts: Variables, conditionals, systemctl command integration
• Key Learning: Combine user input with system commands for automation

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2. Shell Scripting: Loops, Arguments & Error Handling

Scripts demonstrating control flow and robust script design.

for_loop.sh

• Purpose: Iterate through arrays using for loops
• Concepts: Array definition, for-in loops, array expansion
• Key Learning: Loop through collections efficiently

count.sh

• Purpose: Print numbers 1-10 using C-style for loops
• Concepts: C-style for loop syntax, numeric iteration
• Key Learning: Alternative loop syntax for numeric ranges

countdown.sh

• Purpose: Countdown timer using while loops
• Concepts: While loops, variable arithmetic, sleep command
• Key Learning: While loops for condition-based iteration

greets.sh

• Purpose: Accept command-line arguments
• Concepts: $1 positional argument, argument validation, usage messages
• Key Learning: Pass data to scripts via command line

args_demo.sh

• Purpose: Demonstrate all argument variables
• Concepts: $# (argument count), $@ (all arguments), $0 (script name)
• Key Learning: Access and use command-line arguments

install_packages.sh

• Purpose: Automated package installation with status checking
• Concepts: Loops, package manager integration (apt-get), conditional installation
• Key Learning: Automate system administration tasks

safe_script.sh

• Purpose: Error handling best practices
• Concepts: set -e (exit on error), || operator for error handling
• Key Learning: Make scripts fail safely and predictably

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3. Shell Scripting: Functions & Intermediate Concepts

Scripts showcasing modular design and advanced techniques.

functions.sh

• Purpose: Basic function definition and calling
• Concepts: Function syntax, function calls, local variables
• Key Learning: Functions make scripts modular and reusable

disk_check.sh

• Purpose: System resource monitoring with functions
• Concepts: Functions with specific purposes, df and free commands, main function pattern
• Key Learning: Organize scripts with dedicated functions for each task

strict_demo.sh

• Purpose: Demonstrate strict mode options
• Concepts: set -e, set -u, set -o pipefail
• Key Learning: Use strict mode flags to catch errors early

local_demo.sh

• Purpose: Local vs. global variable scope
• Concepts: local keyword, variable scope, function isolation
• Key Learning: Local variables prevent variable leakage between functions

system_info.sh

• Purpose: Comprehensive system information reporter
• Concepts: Multiple functions, command substitution, output formatting
• Key Learning: Combine multiple functions for complex reporting tasks

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4. Shell Scripting Project: Log Rotation, Backup & Crontab

Production-ready scripts for server maintenance automation.

log_rotate.sh

• Purpose: Automated log file management
• Concepts: find command, gzip compression, file deletion, timestamps
• Key Learning: Compress logs older than 7 days; delete .gz files older than 30 days
• Usage: `./log_rotate