Bash script arguments from a file content:Mastering Shell Scripting

Introduction

Learn how to change string content of a file using bash script arguments. This guide provides detailed steps and examples, from default values to custom arguments. Master shell scripting to dynamically update file content efficiently.

Bash scripting is a versatile and powerful tool for automating tasks and managing system operations. One common requirement is changing specific string content in a file using arguments passed to a script. This guide will demonstrate how to achieve this with a bash script, covering both default values and custom arguments. By following this tutorial, you will enhance your scripting skills and be able to dynamically update file content efficiently.

In this tutorial, how to change string content of file as arguments. I written  Bash script arguments from a file content as below:

What is Bash Scripting?

Bash scripting involves writing a series of commands in a text file to be executed by the Bash shell. It is widely used for automating repetitive tasks, managing system operations, and simplifying complex command sequences.

Key Benefits of Bash Scripting

• Automation: Streamline repetitive tasks.
• Efficiency: Simplify complex command sequences.
• Productivity: Enhance operational workflows.

Why Change File Content with Script Arguments?

Changing file content using script arguments allows for dynamic and flexible script execution. It enables users to update file content without manually editing the file, making the script more reusable and adaptable to different scenarios.

Benefits of Using Script Arguments

• Flexibility: Easily change file content based on input arguments.
• Scalability: Handle different data sets without modifying the script.
• Maintainability: Simplify script management and updates.

Basic Script Setup

Let's start with a basic setup for our script. We will create a script that reads an input file, replaces specific placeholders with arguments, and writes the modified content to an output file.

Input File

Create an input file input.txt with the following content:

My name: NAME
My Blog: https://DOMAIN.com

Output file with arguments default value

My name: Huu
My Blog: https://huuphan.com

Output file with arguments another value

My name: Devops
My Blog: https://devopsroles.com

My bash script 

$ cat arguments_file.sh

The content bash script

#!/bin/bash

# Default values for arguments

argument1=Huu

argument2=huuphan

# Input and output file paths

INPUT=/home/huupv/scripts/input.txt

OUTPUT=/home/huupv/scripts/output.txt

# Check if arguments are provided

if [ $# -eq 2 ]; then

    argument1=$1

    argument2=$2

fi

# Replace placeholders in the input file and write to the output file

sed -f - "$INPUT" > "$OUTPUT" <<EOF

s/NAME/$argument1/g

s/DOMAIN/$argument2/g

EOF

Running bash script with default value

$ ./arguments_file.sh

The output as picture below:

Running Script with Custom Arguments

To replace the placeholders with custom arguments, pass the arguments when running the script.

Running the Script with Custom Arguments

Run the script with custom arguments:

$ ./arguments_file.sh Devops devopsroles

The display as picture below:

FAQs

How do I change multiple placeholders in a file using bash script?

Use sed with multiple s/placeholder/replacement/g commands to change multiple placeholders.

Can I pass more than two arguments to the script?

Yes, modify the script to handle additional arguments as needed.

What if the input file does not exist?

Add error handling to check if the input file exists before processing:

if [ ! -f "$INPUT" ]; then
    echo "Input file not found!"
    exit 1
fi

How do I handle spaces in arguments?

Wrap the arguments in quotes when passing them to the script:

./arguments_file.sh "Dev Ops" "devops roles"

Conclusion

Changing string content in a file using bash script arguments is a powerful technique for dynamic file manipulation. By following the examples and best practices outlined in this guide, you can create flexible and efficient scripts that handle varying input scenarios. Whether using default values or custom arguments, mastering this approach will enhance your scripting capabilities and streamline your workflows. Happy scripting! Thank you for reading the huuphan.com page!