Bash Scripting – File Extension

Bash scripting is a powerful tool for automating tasks and working with files in the command line. One important aspect of working with files in bash is understanding how to handle file extensions. In bash, a file extension is the portion of a file name that follows the last period (.) in the file name. For example, in the file name “file.txt“, the file extension is “txt“. File extensions are used to indicate the type of file and to determine which programs should be used to open the file.

Bash scripting is a powerful tool for automating tasks and manipulating files in Linux and Unix systems. One important aspect of bash scripting is working with file extensions. In this article, we will discuss various ways to work with file extensions in bash scripting.

The first step in working with file extensions is to extract the extension from a file name. This can be done using the ‘basename’ and ‘dirname’ commands, which can be used to extract the basename and directory name of a file, respectively. For example, to extract the extension of a file named “example.txt”, we can use the following command:

extension="${file##*.}"

There are several methods to work with file extensions in bash scripting.

Method 1: Extracting the File Extension

To extract the file extension of a file, you can use the ${VARIABLE##*.} syntax, where VARIABLE is the name of the file with the file extension. For example:

filename="file.txt"
extension=${filename##*.}
echo "The file extension is: $extension"

 

This would output the following:

The file extension is: txt

 

Method 2: Changing the File Extension

To change the file extension of a file, you can use the ${VARIABLE%.*}.NEW_EXTENSION syntax, where VARIABLE is the name of the file with the file extension and NEW_EXTENSION is the new file extension you want to use. For example:

filename="file.txt"
new_filename="${filename%.*}.doc"
echo "The new file name is: $new_filename"

 

The output of the above example is shown in the below screenshot.

The new file name is: file.doc

output put

Method 3: Iterating Through Files with a Specific File Extension

You can use a for loop to iterate through all the files in a directory with a specific file extension. For example:

for file in *.txt; do

  echo “Processing $file”

  # do something with the file

done

This would loop through all the files with the “.txt” file extension in the current directory and perform some action on each file.

Method 4: Checking the File Extension

You can use an if statement to check the file extension of a file and perform different actions based on the file extension. For example:

filename=”file.txt”

if [[ “$filename” == *.txt ]]; then

  echo “This is a text file.”

elif [[ “$filename” == *.doc ]]; then

  echo “This is a word document.”

else

  echo “This is another type of file.”

fi

 

This would output the following:

This is a text file.

 

By understanding how to work with file extensions in bash scripting, you can automate tasks and better manage your files in the command line.

In addition to the methods described above, there are a few other ways to work with file extensions in bash scripting.

Method 5: Removing the File Extension

To remove the file extension from a file name, you can use the ${VARIABLE%.*} syntax, where VARIABLE is the name of the file with the file extension. For example:

filename=”file.txt”

no_extension=${filename%.*}

echo “The file name without the extension is: $no_extension”

 

This would output the following:

The file name without the extension is: file

 

Method 6: Finding the File Extension of a File without the Period

To find the file extension of a file without the preceding period, you can use the ${VARIABLE##*.} syntax and then remove the period from the output. For example:

filename=”file.txt”

extension=${filename##*.}

no_period=${extension#.}

echo “The file extension without the period is: $no_period”

 

This would output the following:

The file extension without the period is: txt

 

Method 7: Renaming Multiple Files with a Different Extension

You can use a for loop to rename multiple files with a different file extension. For example:

for file in *.txt; do

  mv “$file” “${file%.*}.doc”

done

 

This would rename all the “.txt” files in the current directory to have a “.doc” file extension.

 

By understanding these different methods of working with file extensions in bash scripting, you can easily manipulate and manage your files in the command line.

Advantages of Bash Scripting – File Extension:

• Easy to Learn: Bash is a relatively simple and straightforward scripting language, making it easy to learn and use, even for those with limited programming experience.
• Cross-Platform Compatibility: Bash scripts are compatible with a wide range of operating systems, including Linux, macOS, and Windows, making them an ideal choice for multi-platform development.
• Automation: Bash scripts can be used to automate repetitive tasks, reducing the need for manual intervention and improving efficiency.
• Interoperability: Bash scripts can interact with other tools and scripts, making it easy to integrate with other systems and technologies.
• Large Community: Bash has a large and active community of users and developers, providing access to a wealth of resources and support.

Disadvantages of Bash Scripting – File Extension:

• Performance: Bash scripts can be slow, particularly for complex or resource-intensive tasks, compared to compiled languages such as C or C++.
• Limited Functionality: Bash scripts have limited functionality compared to other scripting languages, making it challenging to implement complex algorithms or perform data processing tasks.
• Security: Bash scripts are prone to security vulnerabilities, particularly if they are poorly written or if they rely on external programs or tools.
• Error-Prone: Bash scripts can be prone to errors, particularly if they are complex or if they rely on input from other sources.
• Debugging: Debugging Bash scripts can be challenging, particularly if they are large or if they rely on multiple tools or components.

Conclusion

In conclusion, bash scripting provides various methods for working with file extensions, including extracting the file extension, changing the file extension, iterating through files with a specific file extension, checking the file extension, and removing the file extension. These methods can be used to automate tasks and better manage your files in the command line.

 working with file extensions in bash scripting is a powerful tool that allows us to automate tasks and manipulate files in Linux and Unix systems. By extracting the extension from a file name, we can use it in various ways, such as checking the extension, performing batch operations, and searching for files with a specific extension.

No any extension is required for Bash Script File when you mentioned or add Hash Bang, #!/bin/bash , this first line of in code.

The Hash Bang is a Kernel convention and playing roll in the interpreter. Kernel the same validating the interpreter..!! What’s that? Like, The scripts can be written in bash, python, perl, php, etc. And writing the interpreter in Hash Bang is more easy for your Kernel to executing the Script.

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Article Tags :

• Linux-Unix
• Technical Scripter
• Bash-Script
• Technical Scripter 2022