How to Get exe stdout in Real Time in Your Python GUI

Discover how to execute an exe file in Python and get its output live in a PyQt GUI, using `QProcess` for real-time updates.
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How to Get exe stdout in Real Time in Your Python GUI

Running external executable files from your Python application can be quite beneficial, especially when you want to display the output in real-time within a graphical user interface (GUI). However, achieving this functionality can be a bit tricky due to how stdout is buffered. In this post, we'll explore how you can run an executable file, capture its output on-the-fly, and display it using PyQt5.

The Problem

When you execute a command in Python, especially through the subprocess module, you may have noticed that the output is collected and displayed after the execution is complete. This can be frustrating if you want to see real-time output in your GUI while the command is still running.

In a typical scenario, the stdout will only update after the command has finished executing, which can lead to a poor user experience.

Let’s see how to overcome this limitation using PyQt5’s QProcess.

The Solution: Using QProcess

To achieve real-time updates in your GUI, you'll want to utilize QtCore.QProcess, which is designed specifically for this purpose.

Step-by-Step Breakdown

1. Import Necessary Libraries

First, you need to import the necessary components from the PyQt5 library:

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

2. Set Up the Buffer Function

We need a utility function to convert the buffer output from the process into a string suitable for display:

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

3. Create a Process Class

Next, we’ll create a Process class that will manage the execution and signal the GUI for updates:

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

4. Initialize the Application

Now let’s put everything together by creating a simple PyQt application.

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

Explanation of the Code

QProcess: This class is used to start external processes and communicate with them. It has signals for standard output and error, which will allow us to capture live output.

readyReadStandardOutput & readyReadStandardError: These signals are emitted whenever the process has data available to read from its standard output or error. We connect these signals to our custom slots that read and emit the output.

Connecting Signals to Slots: We connect the output signals to display the data in a QPlainTextEdit widget in real-time.

Conclusion

By utilizing QProcess in PyQt5, you can elegantly capture and display real-time stdout (and stderr) from executing external programs within your GUI applications. This method enhances user experience by providing immediate feedback during long-running commands or processes.

Try implementing this in your next application, and enjoy the seamless interaction it offers!