bash

name	bash
description	Bash shell scripting for automation, pipelines, and system administration. Use for .sh files and Linux scripting.

Bash

Bourne Again SHell, the standard shell for Linux and macOS.

When to Use

• Automating system tasks
• CI/CD pipelines
• File manipulation
• Glue code between CLIs

Quick Start

#!/bin/bash

NAME="World"
echo "Hello, $NAME!"

if [ -f "file.txt" ]; then
    echo "File exists"
else
    echo "File not found"
fi

Core Concepts

Variables

No data types. Everything is a string.

count=10
echo $count

Pipes and Redirection

• |: Pipe output of one command to input of next.
• >: Redirect output to file (overwrite).
• >>: Redirect output to file (append).

cat file.txt | grep "error" > errors.log

Exit Codes

Commands return 0 for success and non-zero for failure. Check with $?.

Best Practices

Do:

• Use set -e (e)xit on error
• Use set -u (u)nset variable usage is error
• Use set -o pipefail to catch errors in pipes
• Quote variables "$VAR" to handle spaces

Don't:

• Parse ls output (use globs *)
• Use simple [ vs [[ (double brackets are safer)

References

• ShellCheck
• Google Shell Style Guide