Coding/Learn/bash/bash small real world scripts
Bash Shell & CLI Automation Complete Course
01.What Bash Is & Shell Architecture
02.Terminal and Shell Basics
03.Running Commands & PATH Resolution
04.Command Structure: Options, Flags & Arguments
05.Getting Help with Commands: man, info & --help
06.Basic Filesystem Navigation & Directory Hierarchy
07.Listing Files with ls & Options
08.Changing Directories with cd
09.Current Directory: pwd & $PWD Variable
10.Creating Files: touch, Redirection & Here-Docs
11.Creating Directories with mkdir & Nested Parents
12.Copying Files and Directories with cp
13.Moving and Renaming Files with mv
14.Removing Files and Directories with rm & rmdir
15.Viewing File Contents: cat, less, more, head & tail
16.Command Aliases: alias, unalias & Persistence
17.Searching Text with grep & ripgrep
18.Pattern Matching: Regex & Extended Globs
19.Processing Columns & Structured Data with awk
20.Editing Text Streams with sed
21.Extracting Sections with cut, paste & tr
22.Sorting and Deduplication with sort & uniq
23.Viewing Beginning & End: head, tail & wc
24.Understanding Linux Processes & PID Lifecycle
25.Process Monitoring: top, htop & Background Jobs
26.Monitoring Disk Space with df
27.Directory Size Analysis with du & ncdu
28.Monitoring Memory Usage with free & /proc/meminfo
29.Terminating Processes: kill, killall, pkill & Signals
30.System Uptime, Load & Reboot History
31.Testing Connectivity: ping, nc, traceroute & nslookup
32.Making HTTP Requests with curl
33.Downloading Files with wget & curl -O
34.Remote SSH Connections: ssh, Keys & Config
35.Secure File Transfer with scp & sftp
36.File Synchronization with rsync
37.Creating and Managing ZIP Files
38.Extracting Archives: unzip & Safe Decompression
39.TAR Archives: Tape Archive Basics (tar -cvf, -tvf, -xvf)
40.Creating and Extracting Compressed Files (.tar.gz, .tar.bz2, .tar.xz)
41.Users and Groups: /etc/passwd, /etc/group & id
42.File Ownership: User Owner, Group Owner & Inodes
43.Read, Write & Execute Permissions: Files vs Directories
44.Changing Permissions with chmod: Symbolic & Octal Modes
45.Changing Ownership with chown
46.Changing Groups with chgrp & SetGID Inheritance
47.Script Structure & Strict Mode (set -euo pipefail)
48.The Shebang (#!) & Interpreter Portability
49.Variables: Declaration, Scope & Parameter Expansion
50.Data Types, Typeset & Declare Attributes
51.Operators: Arithmetic, String & Logical Operators
52.Handling User Input: read, Prompts & Secret Masking
53.Conditional Branching: if, elif, else & case Statements
54.Loops: for, while, until & Loop Control (break, continue)
55.Functions: Declarations, Local Scope & Return Values
56.Arrays: Indexed Arrays, Associative Maps & Slicing
57.Exit Codes ($?), Error Handling & Custom Exits
58.Scheduling with Cron & Crontab Automation
59.Combining Commands: Semicolons (;), &&, || & Subshells
60.Pipes (|), Pipefail & Process Pipelines
61.I/O Redirection: >, >>, 2>, 2>&1, &>, /dev/null & Here-Strings
62.Environment Variables: export, env, printenv & .env Loading
63.Command Substitution: $(command) vs Legacy Backticks
64.Basic Automation: Batch Processing & Lockfiles
65.Small Real-World Scripts: Health Checkers & Backup Utilities
66.Comprehensive Bash Exercises: Pipeline & Automation Challenges
67.Core Knowledge Quiz & Conceptual Review
68.Capstone Mini-Project: Automated Backup & Health Dispatcher
69.Course Completion & Verified Certificate
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Lesson 65 of 69
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Small Real-World Scripts: Health Checkers & Backup Utilities

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In Plain English

Mastering Bash culminates in building practical, production-grade CLI utilities: system health check probes, automated directory archiving with timestamped rotations, and alert notification dispatchers.

The Mental Model

"You are now ready to build real automated robots that monitor your infrastructure 24/7, back up your critical data, and alert you before small problems become outages."

Deep Dive: How It Works

Health Check Anatomy: Tests disk usage, memory thresholds, service connectivity, and CPU load in one clean report.

Backup Rotation: Creates timestamped `.tar.gz` archives and automatically prunes backups older than N days (`find /backups -mtime +7 -delete`).

Alert Formatting: Formats structured JSON or text payloads ready for Slack/Discord webhooks or email dispatch.

Syntax Blueprint

# Complete Backup & Health Check Architecture:
1. Verify dependencies (which tar gzip curl)
2. Acquire atomic lock
3. Package files with timestamp (tar -czf backup_$(date +%F).tar.gz)
4. Prune old archives (find ... -mtime +30 -delete)
5. Send success notification to monitoring webhook

Combine defensive scripting principles to build reliable production utilities.

PointCore Rules to Remember

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Automated Pruning: `find /backups -name "*.tar.gz" -mtime +14 -delete` keeps storage bounded.
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Idempotency: Scripts can run repeatedly without corrupting data or duplicating work.
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Exit Code Status: Return 0 on complete success, 1 on health warning, 2 on fatal error.

Common Beginner Traps & How to Fix Them

Mistake:Writing backup scripts that fill up disk without an automated retention pruning policy.

Why it happens: Daily backups grow continuously until the server runs out of disk space.

How to fix: Always pair backup creation with an automated retention cleanup step using `find -mtime`.

Pro Tip: Use `logger -t "my-backup-script" "Backup completed successfully"` to write messages directly to the systemd/syslog journal.

Live Interactive Example

Hit Run Code to see it live
Complete Production Server Health Checker Script
Git 2.45 / CLI
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Output Console
Click "Run Code" to view the rendered output.
How it works: The complete script queried uptime, parsed disk utilization, measured RAM, and output a clean status report.

Your Turn: Micro Challenge

No pressure! Edit the starter code below and test your solution with instant feedback.

Micro Exercise

Run a Server Health Check Report

  • PointEcho "Status: ALL SYSTEMS OPERATIONAL" to verify health check completion.
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Sandbox Output
Click "Run & Check" to test your solution.

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