Скачать или смотреть Solving the stdin and stdout Puzzle in Go: How to Connect Running Commands

Learn how to send `stdout` of a running command to its `stdin` using Go. We’ll break down the solution step by step so you can implement it in your own applications.
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This video is based on the question https://stackoverflow.com/q/73341110/ asked by the user 'cheveuxdelin' ( https://stackoverflow.com/u/13563563/ ) and on the answer https://stackoverflow.com/a/73347928/ provided by the user 'Shang Jian Ding' ( https://stackoverflow.com/u/4904673/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Solving the stdin and stdout Puzzle in Go

In programming, particularly when working with Go, you might encounter situations where you need to manage input and output streams between different processes. A common challenge is sending the stdout (standard output) of one command to the stdin (standard input) of another. This might be essential for applications that require seamless communication between processes.

In today's post, we will explore how to achieve this using Go. We'll look at a specific example involving a greeting program that randomly returns a greeting and reads user input to respond accordingly.

The Challenge

You want to create an application that:

Outputs a random greeting.

Reads input from the user.

Confirms whether the input matches the greeting provided.

However, a hurdle arises because you want the program to send the stdout directly into the stdin of another command while it's still running. Many attempts to use standard input-output connections often lead to issues like the program freezing, especially when stdin is closed prematurely.

Let’s simplify this process through the following steps.

The Solution: Using Pipes

Step 1: Create the Pipe Connection

A pipe allows you to connect the stdout of one command to the stdin of another. This is how you can set it up in your Go application:

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

Step 2: Preparing the Test Program

For testing, you can prepare a simple program that does the following:

Prints a message to stdout.

Reads from stdin line by line and echoes it.

Here’s an example of such a program:

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

Step 3: Modifying Your Original Program

To see the connections in action, you can add "spy" functionality to monitor what is being read and written through the pipe:

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

Step 4: Running the Code

Once you have set everything up, running your Go program will demonstrate the real-time passing of output and input:

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

Conclusion

By using io.Pipe(), you've successfully connected the stdout of one process to the stdin of another. This technique allows for elegant inter-process communication in Go, effectively enabling responsive applications that can handle user inputs based on ongoing output.

Now you have a robust solution to your problem! Feel free to expand on this basis to suit your specific requirements.