The subprocess module in Python allows us to spawn new processes, connect to their input/output/error pipes, and obtain their return codes. One of the essential features of subprocess is the ability to set the standard output handle.

What is a standard output handle?

In the context of subprocess operations, a standard output handle refers to the mechanism through which a program writes its output. By default, the standard output handle is set to the console where the program is executed. However, with subprocess, we can redirect this output to other sources, such as files or variables.

Using subprocess.STD_OUTPUT_HANDLE

To set the standard output handle using subprocess, we can make use of the stdout parameter in the subprocess.Popen() function. By default, stdout is set to None, which means the output will be redirected to the console.

However, by specifying a value for stdout, we can redirect the output to other destinations. In this case, we can use the subprocess.STD_OUTPUT_HANDLE constant.

Example

import subprocess

# Create a subprocess with the standard output handle set to subprocess.STD_OUTPUT_HANDLE
process = subprocess.Popen(['ls'], stdout=subprocess.STD_OUTPUT_HANDLE)

# Wait for the process to complete
process.wait()

In the example above, we create a subprocess using the Popen() function, passing the command ls as an argument. We set the stdout parameter to subprocess.STD_OUTPUT_HANDLE, which redirects the output to the standard output handle. Finally, we wait for the process to complete by calling process.wait().

By using subprocess.STD_OUTPUT_HANDLE, we can easily redirect the output of a subprocess to different destinations and capture or process it as needed.

Conclusion

Setting the standard output handle using subprocess.STD_OUTPUT_HANDLE in Python allows us to redirect the output of a subprocess to different sources. This can be useful for capturing and processing the output in our Python code.