Bash

Description #

Bash (Bourne Again SHell) is a Unix shell and command language widely used for automating tasks, managing files, executing scripts, and controlling system processes. It is the default shell on most Linux distributions and macOS systems, making it essential for system administrators, DevOps engineers, and developers.

History #

Bash was developed by Brian Fox for the GNU Project and first released in 1989 as a free software replacement for the original Bourne shell (sh). It was designed to be POSIX-compliant while including useful features from KornShell (ksh) and C shell (csh).

Bash became the default shell on most Unix-like systems, including Linux and macOS (until replaced by Zsh in macOS Catalina). It remains foundational in scripting, automation, and shell-based programming.

Hello World Code #

#!/bin/bash
echo "Hello, World!"

How to Run #

Save the code to a file named hello.sh

Make it executable:

chmod +x hello.sh

Run it:

./hello.sh

📝 Alternatively, run directly with:

bash hello.sh

Key Concepts #

#!/bin/bash — shebang line that defines the interpreter

echo — prints text to the terminal

Shell scripting — automates command sequences

Environment variables — store reusable values

Conditionals — if, else, elif

Loops — for, while, until

Command substitution — using $(...)

Exit codes — represent script success or failure

Permissions — execution rights via chmod

Glob patterns — for filename matching (e.g., *.txt)

Try It Online #

🔗 Tutorialspoint Bash Compiler
🔗 JDoodle – Bash
🔗 Replit – Bash

Fun Facts #

Bash is installed by default on virtually every Linux system

The name “Bourne Again” is a play on the Bourne Shell (sh)

Bash scripts are used for server startup, build pipelines, and automation

macOS switched to Zsh as the default shell in 2019, but Bash is still included

You can write entire applications using just Bash

Resources #

GNU Bash Manual

Bash Beginner’s Guide – LinuxConfig

ShellCheck (Linter)

ExplainShell (Command Breakdown)