This content originally appeared on DEV Community and was authored by Md Abu Musa
Shell scripting is a way to automate repetitive tasks, manage system operations, and create custom utilities using a command-line interpreter, like bash, sh, zsh, or ksh. A shell script is simply a text file containing a series of commands that you would normally type into a terminal manually.
Step-by-Step Guide to Start Shell Scripting:
Step 1: Understanding Shell Scripting
- Definition: Shell scripts are files containing sequences of shell commands to be executed in order.
- Purpose: Automate tasks like backups, system monitoring, file manipulations, and installations.
-
Basic Shells: Common shell interpreters include:
-
bash(Bourne Again Shell) -
sh(Bourne Shell) -
zsh(Z Shell) -
ksh(Korn Shell)
-
For beginners, the bash shell is the most widely used and recommended.
Step 2: Setting Up the Environment
-
Choose an Editor:
Use a text editor to create and edit shell scripts:-
CLI Editors:
nano,vim,emacs -
GUI Editors:
VS Code,Sublime Text,Atom
-
CLI Editors:
Create a New Script File:
Open the terminal and create a new file using thetouchcommand:
touch my_first_script.sh
-
Make the Script Executable:
To execute your script, it must have executable permissions. Grant it using
chmod:
chmod +x my_first_script.sh
Step 3: Writing a Basic Shell Script
- Open the Script in an Editor:
nano my_first_script.sh
-
Start with a Shebang:
The first line of a shell script should specify the shell to use, using the shebang (
#!) syntax:
#!/bin/bash
This tells the system that it should use the bash shell to run the script.
- Add Commands: Begin by adding some basic commands:
#!/bin/bash
echo "Hello, World!"
-
echois used to print text to the terminal.
-
Save and Exit:
In
nano, pressCTRL + X, thenY, and hitENTERto save and exit.
Step 4: Running Your First Shell Script
- Execute the Script: In the terminal, run the script by specifying its path:
./my_first_script.sh
You should see the output:
Hello, World!
Step 5: Adding Logic and Functionality
Expand your script by adding variables, conditional statements, loops, and functions:
- Variables:
#!/bin/bash
name="John"
echo "Hello, $name!"
- Conditionals:
#!/bin/bash
age=25
if [ $age -ge 18 ]; then
echo "You are an adult."
else
echo "You are a minor."
fi
- Loops:
#!/bin/bash
for i in 1 2 3 4 5; do
echo "Iteration: $i"
done
- Functions:
#!/bin/bash
greet() {
echo "Hello, $1!"
}
greet "Alice"
greet "Bob"
Step 6: Handling Input and Output
- Read User Input:
#!/bin/bash
echo "Enter your name:"
read name
echo "Welcome, $name!"
- Redirecting Output: Save command output to a file:
echo "This is a log file." > log.txt
- Appending to Files: Append content to an existing file:
echo "This will be added to the log file." >> log.txt
- Handling Arguments: Use positional parameters to handle script arguments:
#!/bin/bash
echo "The first argument is: $1"
echo "The second argument is: $2"
Run with:
./my_first_script.sh arg1 arg2
Step 7: Debugging and Improving Your Script
-
Debugging:
Run the script with
-xto see each command as it is executed:
bash -x my_first_script.sh
-
Comment Your Code:
Use comments (
#) to explain your code:
# This is a comment
echo "Hello, World!" # Print Hello
-
Error Handling:
Use
||and&&for simple error handling:
mkdir new_directory && cd new_directory || echo "Failed to create or navigate to directory."
This content originally appeared on DEV Community and was authored by Md Abu Musa
Md Abu Musa | Sciencx (2024-10-02T17:21:03+00:00) Step-by-Step Guide to Start Shell Scripting.. Retrieved from https://www.scien.cx/2024/10/02/step-by-step-guide-to-start-shell-scripting/
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