How to Process File Content Differently for Each Line Using Shell Script

Learn how to efficiently process each line of a file in shell scripting, breaking down content into manageable variables for further use.
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How to Process File Content Differently for Each Line Using Shell Script

When working with data files in shell scripting, processing each line differently can often be a requirement. Today, we will explore how to read a file with a specific structure and extract its contents into different variables. Let’s look at a practical scenario and break down the process!

The Problem

Imagine you have a file with the following data structure:

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In your task, you need to read this file and store the view and table data in separate variables. After that, you will use these variables in a loop to extract specific components such as the object type, schema, view, and file location.

The Solution

Step 1: Extract Data from the File

First, you can extract the relevant portions of the file using the sed command. Here’s how you can achieve this:

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This code does the following:

It captures everything from the view: line up to the tables: line in the viewData variable.

It captures everything from the tables: line up to the end: line in the tableData variable.

You can echo these variables to check their content:

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Step 2: Process Each Line of Data

To process the data further and split it into components, you can use an awk command. Here’s a powerful one-liner that accomplishes this:

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Breakdown of the awk Command

match($0,/[^[:space:]]+:/) identifies lines that start with a key followed by a colon.

key gets the object type (like view or tables).

val holds the file's path.

The index function checks for the dot (.) in the key to differentiate between views and tables.

The output is printed in the required format:

objType

schema

view or table

fileLoc

Expected Output

When you run the awk command, the output will look similar to this:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By utilizing shell scripting along with commands like sed and awk, you can efficiently process file contents based on your needs. This approach allows you to extract and manage data systematically, making your scripts cleaner and more effective.

If you encounter structured files often, mastering these commands will significantly enhance your scripting capabilities. Happy scripting!