What Bash scripting is used for in real DevOps, Linux administration, and automation

How to approach scripting: small reliable scripts first, then frameworks and tooling

Setting up your lab: Linux VM/WSL, terminal tools, editors, permissions

Understanding script lifecycle: write → test → debug → package → schedule → monitor

Naming standards, folder structure, and safe scripting habits from day one

Shell vs terminal vs console: clear understanding

Bash startup files: .bashrc, .bash_profile, .profile and what loads when

Environment basics: PATH, HOME, SHELL, variables, exports

Working with files and directories quickly: ls, cd, pwd, mkdir, cp, mv, rm

Permissions basics: chmod, chown, umask, and why they matter in scripts

Redirection and pipes: >, >>, <, 2>, &>, |

Shebang (#!/bin/bash) and how script execution works

Running scripts: ./script.sh vs bash script.sh and what changes

Making scripts portable across systems

Script inputs and outputs (stdin/stdout/stderr)

Exit codes: success vs failure, and why automation depends on them

Writing your first automation script: a simple system check and report

Variables in Bash: assignment, reading, and exporting

Single quotes vs double quotes vs no quotes (and common mistakes)

Command substitution: $(...) vs backticks

Arithmetic in Bash: let, (( )), $(( ))

Strings and concatenation techniques

Special variables: $0, $1..$9, $#, $@, $*, $?, $$, $!

Using defaults and fallbacks: ${var:-default}, ${var:=default}

Positional parameters and safe parsing habits

Building clean usage/help menus for scripts

Reading input with read (silent input, prompts, timeouts)

Validating inputs and rejecting unsafe values

Interactive vs non-interactive scripting best practices

Creating a standard “CLI style” script template

Test commands: [ ], [[ ]], and test (when to use what)

File tests: -f, -d, -r, -w, -x, -s

String tests and comparisons

Numeric comparisons: -eq, -ne, -gt, -lt, etc.

Combining conditions: &&, ||, !

Pattern matching and safer comparisons with [[ ]]

if, elif, else best practices with readable structure

case statements for menu-driven scripting

Loops: for, while, until (and when each is ideal)

Loop control: break, continue

Iterating over files safely (spaces, special characters, null globs)

Building a batch processing script: rename, move, archive, report

Creating functions with clean input/output behavior

Local variables and avoiding global variable conflicts

Returning values: exit codes vs echo output

Organizing scripts into reusable libraries

Sourcing external files: source and .

Building a “common.sh” utilities library used by multiple scripts

Reading files line-by-line safely

Redirections in depth and log management

Here strings and here documents: <<< and <<EOF

cat, tee, tr, cut, paste, sort, uniq, wc usage in pipelines

Powerful text processing with grep, sed, awk (intro to advanced)

Creating a log parser script: extract errors, summarize, alert

Regex basics for Linux tools

grep -E patterns and practical matching

sed substitution patterns and safe replacements

awk field processing and report generation

Building a data cleanup script for CSV and log formats

Substring, replace, length operations: ${#var}, ${var:pos:len}

Find/replace patterns: ${var/pat/repl}, ${var//pat/repl}

Removing prefixes/suffixes: ${var#}, ${var##}, ${var%}, ${var%%}

Building clean file/path utilities using expansion

Defensive coding to avoid breakage across environments

Understanding process lifecycle and signals

Running background jobs and capturing PIDs

ps, top, pgrep, pkill, kill, trap usage

Handling script interruptions: cleanup on exit with trap

Timeouts and command retries (reliable automation pattern)

Writing a service monitor script that restarts a process safely

Strict modes: set -e, set -u, set -o pipefail (what they do and pitfalls)

Debug modes: set -x, bash -x script.sh

Logging standards: timestamped logs, levels, and log rotation basics

Handling failures gracefully with clean messages and exit codes

Creating robust retry logic with backoff

Writing scripts that are safe in production environments

Automating with cron: patterns, crontab rules, env issues

at and one-time job scheduling

Using systemd timers (intro)

Safe scheduling: locking to prevent double runs

Building a daily backup script with retention policy and logging

Checking network and DNS from scripts

Using curl and wget for API calls and downloads

Parsing JSON quickly (intro with common approaches)

SSH automation concepts: keys, non-interactive SSH, remote commands

Building a remote health-check script for multiple servers

OS identification and environment detection

Managing services: systemctl basics from scripts

Disk, memory, CPU reporting: df, du, free, uptime, vmstat

User and group checks: id, /etc/passwd, /etc/group

Writing a system audit script for Linux machines

Avoiding injection risks and unsafe eval patterns

Safe handling of secrets and credentials

Permissions and ownership best practices for scripts and log files

Validating external inputs and sanitizing file names

Using safe temporary files with mktemp

Building scripts that pass basic security review

Creating subcommands: tool start|stop|status pattern

getopts for flags like -f, -v, -n, -o

Verbose vs quiet modes

Config file support (.env, .conf) and defaults

Color output (optional) and clean formatting

Deliverable: a production-grade CLI script template

Using Bash in CI/CD pipelines (Jenkins/Bamboo/GitLab CI concept)

Writing scripts for build, test, packaging, deployments

Managing environment variables in pipelines

Artifact handling: creating tarballs, checksums, and validations

Writing a deployment helper script for staging and production

Build a complete automation solution using everything learned

Suggested capstone options (choose one):

• Log monitoring + alert summary generator

• Backup + retention + upload + verification automation

• Server audit + report + remediation suggestions

• Deployment helper tool with rollback and checks

Add features: argument parsing, logging, error handling, retries, locking

Final presentation: script design, decisions, and testing outcomes