The Ultimate Programmer’s Guide to Bash Scripting

A deep dive into Bash scripts to help you automate tasks

Photo by Jeremy Bishop on Unsplash

[Updated on 2021–02-18. Code changed to Gist and added links]

Introduction

Bash scripts allow you to automate command-line tasks. For example, watch this video. The video shows how to automate creating a YouTube channel with Bash scripts. After watching it, you may want to create your own YouTube channel. For another example, in this article, I automated common terminal tasks.

In this article, we’ll cover basic Bash scripting for beginners and create simple executable scripts.

Let’s dive into Bash scripting!

Table of Contents
· Introduction
· Setting Things Up
  ∘ Mac
  ∘ The bin directory
· VSCode Extensions
· Getting Started
  ∘ Shebang
  ∘ Comment
· Variables
  ∘ Variable assignment
  ∘ Environment variables
  ∘ Internal variables
  ∘ Assigning the command output to a variable
  ∘ Built-in commands
· Tests
  ∘ if statement
  ∘ Spaces Matter
  ∘ Test file expressions
  ∘ Test string expressions
  ∘ Test integer expressions
  ∘ Double parentheses
· How To Use if/else and if/elif/else Statements
· Double Brackets
· How To Use for Loops
  ∘ Using a for loop to rename files
· How To Use Parameters
· How To Accept User Input
· Brace Expansion Using Ranges
· How To Use While Loops
· What Are Exit Status/Return Codes?
  ∘ Checking the exit status
· How To Connect Commands
  ∘ Logical operators and the command exit status
  ∘ Exit command
  ∘ Logical AND (&&)
  ∘ Logical OR (||)
  ∘ The semicolon
  ∘ Pipe |
· Functions
  ∘ Function parameters
· Variable Scope
  ∘ Local variables
· Function Exit Status
· Checklist
· Conclusion
  ∘ Newsletter
  ∘ References

Setting Things Up

Mac

You can check your Bash version:

$ bash --version
GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin19)
Copyright (C) 2007 Free Software Foundation, Inc.

Let’s upgrade the Bash version:

$ brew install bash

You can list all of the instances of executables found.

$ which -a bash
/usr/local/bin/bash…