How to Efficiently Print Two Fields from a Text File in Linux Using AWK

Описание: Discover a straightforward method to `extract multiple fields` from a text file in Linux with the AWK command, using practical examples.
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This video is based on the question https://stackoverflow.com/q/62470443/ asked by the user 'Jack Anderson' ( https://stackoverflow.com/u/10910203/ ) and on the answer https://stackoverflow.com/a/62470678/ provided by the user 'Ed Morton' ( https://stackoverflow.com/u/1745001/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Efficiently Print Two Fields from a Text File in Linux Using AWK

When working with log files, you may find yourself needing to extract specific pieces of information quickly. Whether you're troubleshooting an issue or simply analyzing logs, knowing how to print multiple fields from a text file can save you time. In this guide, we'll focus on printing the date and the filename from a log file using the powerful awk command in Linux.

The Challenge

Imagine you have a log file filled with lines of structured data, each containing multiple fields separated by delimiters. For example, you might have log entries like this:

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

From this data, you want to extract:

The date and time: 2020-06-18 00:01:31

The filename: ovou20200617_999_400280.unl

The Solution: Using AWK

Why Use AWK?

awk is a versatile command-line tool that is perfect for this job. It allows you to manipulate text in powerful ways without needing additional tools like grep or cat. Instead of chaining commands together, you can accomplish your goal in one awk command.

The Command

Here’s a solution that prints the date and filename together:

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

Let's break down this command:

awk: Invokes the awk command.

-F'[|/]': Sets the input field separator to either | or /, allowing us to access data within those delimiters easily.

-v OFS='|': Sets the output field separator to |, so the printed fields will be separated in the same way.

/CUploadProcessRemoteFile.cpp/: This pattern matches any line containing CUploadProcessRemoteFile.cpp, filtering the input. Depending on your needs, you can adjust or remove this filter.

{print $1, $NF}: This part tells awk to print the first field (date and time) and the last field (the filename).

Example Output

When you run the provided command on your log file, you will get output similar to this:

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

Conclusion

Extracting fields from log files using awk streamlines your workflow significantly and enhances your efficiency in data handling. Remember, instead of combining tools like grep and cat, rely on awk alone to manage your text processing needs.

Final Thoughts

Try experimenting with different fields and log formats, and you'll quickly see just how powerful awk can be in your daily tasks. Happy logging!