Скачать или смотреть How to Print Logs into File and CLI in Linux Using tee

Learn how to print logs from your Java Spring Boot app to both the command line and a file simultaneously using the `tee` command in Linux.
---
This video is based on the question https://stackoverflow.com/q/67848466/ asked by the user 'kivin6866' ( https://stackoverflow.com/u/16136278/ ) and on the answer https://stackoverflow.com/a/67848472/ provided by the user 'deepakchethan' ( https://stackoverflow.com/u/7836833/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to print logs into file and in the cli in Linux

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Print Logs into File and CLI in Linux

When working with applications on Linux, especially Java Spring Boot apps, developers often find themselves needing to view log outputs both in the command line interface (CLI) and save them to a file at the same time. If you’ve been struggling to achieve this, you’re not alone. Let's dive into how to print logs into a file and the CLI simultaneously, using a simple command line tool called tee.

The Challenge

You may have encountered a situation similar to this: You're running a Spring Boot application via a command line instruction such as this:

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

You want to see the logs printed in your terminal while also storing them in a file. Traditionally, you might have been limited to printing to the terminal OR writing to a file, missing out on the ability to leverage both outputs at the same time.

The Solution: Using tee

The solution to this common scenario lies in the tee utility. This command allows you to read from standard input and write to standard output and files simultaneously. Here's how you can implement it:

Step-by-Step Instructions

Install tee (if not already installed):
Most Linux distributions come with tee pre-installed as part of the core utilities. You can check if it's available by typing tee --version in your terminal.

Run Your Spring Boot Application with tee:
You can execute the following command to get both outputs:

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

In this command:

java -Dserver.port=5743 -jar somejar.jar is your original command that starts the application.

The | symbol (pipe) takes the output of the preceding command and passes it as input to the next command.

tee output.file writes the logs to output.file while still displaying them in the CLI.

Understanding the Command Breakdown

| (Pipe): This symbol is crucial as it allows for the output from one command to be used as input for another.

tee: This command takes the log output and splits it, sending one copy to the terminal (standard output) and another to the specified file (output.file in this case).

output.file: This is the name of the file where your logs will be saved. You can specify any path or filename that suits your project needs.

Benefits of Using tee

Real-Time Monitoring: By using tee, you can monitor logs in real-time while still retaining a copy for future reference.

Debugging Ease: Having access to both outputs can be a huge advantage when you are debugging issues in your application.

Flexibility: You can easily redirect your logs to different files or store them in a structured format by running multiple commands with tee.

Conclusion

With this simple utility, you can enhance your logging strategy in Linux, especially while running your Java applications. The tee command allows you to capture and view logs simultaneously, improving your workflow and efficiency. Next time you're executing a Spring Boot application, make sure to incorporate this approach and enjoy the benefits of dual log output!

Experience greater control and oversight of your applications – happy coding!