/bæʃ/
noun … “a Unix shell and command language for interacting with operating systems.”
Bash, short for Bourne Again SHell, is a widely used command-line interface and scripting language for Unix-like operating systems, including Linux and macOS. It extends the functionality of the original Bourne shell (sh) by adding command-line editing, job control, shell functions, and scripting constructs such as loops, conditionals, and variables. Bash enables users to execute commands interactively or automate complex sequences of operations through scripts.
At its core, Bash interprets user input or script files, parses commands, manages processes, and interacts with the file system. Common operations include file manipulation, program execution, environment configuration, and text processing. It integrates seamlessly with other Unix utilities such as grep, sed, and awk, allowing complex pipelines that process and transform data efficiently.
Bash supports scripting features like variables, arrays, string manipulation, arithmetic operations, and functions. Scripts can be scheduled for execution via cron jobs or triggered by system events, making Bash a cornerstone for system administration, automation, DevOps workflows, and deployment pipelines. Its compatibility with POSIX standards ensures that scripts are portable across Unix-like systems.
Conceptually, Bash interacts with other shells and programming environments. For example, it can invoke Python, Julia, or compiled binaries within scripts, chain grep and sed for text processing, or manipulate files in coordination with rsync and Git. This makes it both a command interpreter and a lightweight programming language tailored for system-level operations.
An example of a simple Bash script:
#!/bin/bash
# List all .txt files and count lines
for file in *.txt; do
echo "$file has $(wc -l < $file) lines"
done
The intuition anchor is that Bash acts like a versatile “control panel” for Unix systems: it translates user intentions into system commands, automates workflows, and orchestrates processes, empowering users to manage and interact with their operating system efficiently through both interactive use and scripts.