A bash scripting cheat sheet is the perfect reference for Linux users, system administrators, and developers who want to automate tasks and save time. Bash (Bourne Again Shell) is the most common shell in Unix-like operating systems, making it an essential skill for anyone working with Linux. This guide provides quick access to the most useful Bash commands, syntax, and scripting techniques.
Table of Contents
What is Bash and Why Use a Bash Scripting Cheat Sheet?
Bash is both a command processor and a scripting language. It allows users to execute commands interactively or automate workflows with scripts. By combining commands, conditionals, and loops, you can write powerful scripts that manage files, monitor systems, and deploy applications.
A bash scripting cheat sheet saves time by giving you quick access to commands and syntax without memorizing everything. Whether you are writing a simple automation script or managing production servers, a cheat sheet ensures you always have the essentials at hand.
Bash Basics Every Beginner Should Know
Running a Script
Create a file with .sh extension, make it executable, and run:
chmod +x script.sh
./script.sh
Shebang Line
At the top of every Bash script, include:
#!/bin/bash
This tells the system which interpreter to use.
Comments
# This is a comment in Bash
These basics are the foundation of any bash scripting cheat sheet.
Bash Scripting Cheat Sheet: Variables
Variables store data that can be reused in scripts.
Defining Variables
name="Alice"
Accessing Variables
echo "Hello, $name"
Environment Variables
echo $HOME
echo $PATH
Variables make Bash scripts flexible and reusable.
Bash Operators and Expressions
Bash provides arithmetic, comparison, and logical operators.
Arithmetic
x=5
y=3
echo $((x + y))
Comparison
[ $x -eq $y ] # equal
[ $x -lt $y ] # less than
[ $x -gt $y ] # greater than
Logical
[ $x -eq 5 ] && echo "x is 5"
[ $y -ne 5 ] || echo "y is not 5"
Operators are always included in a bash scripting cheat sheet since they are widely used.
Bash Cheat Sheet for Conditionals
Conditionals control the flow of execution.
If Statement
if [ $x -gt 10 ]; then
echo "x is greater than 10"
fi
If-Else
if [ $x -eq 10 ]; then
echo "x is 10"
else
echo "x is not 10"
fi
Nested If
if [ $x -gt 10 ]; then
echo "Greater"
elif [ $x -eq 10 ]; then
echo "Equal"
else
echo "Smaller"
fi
Conditionals form the decision-making part of scripts.
Bash Scripting Cheat Sheet for Loops
Loops repeat tasks efficiently.
For Loop
for i in {1..5}; do
echo "Number $i"
done
While Loop
count=1
while [ $count -le 5 ]; do
echo "Count $count"
((count++))
done
Until Loop
count=1
until [ $count -gt 5 ]; do
echo "Count $count"
((count++))
done
Loops make Bash automation powerful.
Bash Functions
Functions group reusable code blocks.
Defining a Function
greet() {
echo "Hello, $1"
}
Calling a Function
greet Alice
Functions improve script readability and maintainability.
Input and Output in Bash
Reading User Input
echo "Enter your name:"
read username
echo "Welcome, $username"
Redirecting Output
echo "Hello" > file.txt # overwrite
echo "World" >> file.txt # append
Redirecting Errors
command 2> error.log
Input/output handling is essential in any bash scripting cheat sheet.
Bash Arrays
Bash supports indexed arrays.
Declare an Array
fruits=("apple" "banana" "cherry")
Access Elements
echo ${fruits[0]}
Loop Through Array
for fruit in "${fruits[@]}"; do
echo $fruit
done
Arrays are very useful when dealing with lists of values.
File and Directory Operations
File handling is one of the most common Bash tasks.
Check File Existence
if [ -f file.txt ]; then
echo "File exists"
fi
Check Directory
if [ -d /home/user ]; then
echo "Directory exists"
fi
Create and Remove
mkdir mydir
rm -r mydir
These commands are must-have entries in a bash scripting cheat sheet.
Bash Script Exit Codes
Exit codes indicate script success or failure.
0→ Success1→ General error2→ Misuse of shell command127→ Command not found
Check Exit Status
command
if [ $? -eq 0 ]; then
echo "Success"
else
echo "Failure"
fi
Exit codes are essential for debugging scripts.
Advanced Bash Scripting Cheat Sheet Commands
Case Statement
read -p "Enter a number: " num
case $num in
1) echo "One" ;;
2) echo "Two" ;;
*) echo "Other" ;;
esac
Trap Signals
trap "echo 'Script interrupted'; exit" SIGINT
Scheduling with Cron
crontab -e
These advanced commands make Bash scripts more professional.
Best Practices for Bash Scripting
- Always use comments to explain complex code.
- Test scripts in a safe environment before production.
- Use functions and modular design for readability.
- Validate inputs to avoid unexpected errors.
- Follow shell scripting conventions like proper indentation.
Combining these tips with a bash scripting cheat sheet improves both efficiency and reliability.
FAQs About Bash Scripting Cheat Sheet
1. What is a bash scripting cheat sheet?
A bash scripting cheat sheet is a quick reference guide with commands, syntax, and examples for writing Bash scripts in Linux.
2. How do I start learning Bash scripting?
Begin with simple scripts like printing text or looping, and use a bash scripting cheat sheet for quick syntax reminders.
3. Can I automate tasks using Bash scripts?
Yes, Bash scripts are commonly used to automate backups, deployments, and monitoring tasks.
4. Is Bash scripting hard to learn?
No, Bash scripting is beginner-friendly. With practice and a cheat sheet, you can learn it quickly.
5. How do I download a bash scripting cheat sheet PDF?
You can save this guide as a PDF or use official Linux documentation.