How to Implement Asynchronous Shell Command Execution in Python?

Asynchronous Shell Command Execution in Python

To facilitate the asynchronous execution of external shell commands within a Python script, one might contemplate employing the os.system() function. However, this approach introduces the utilization of the & symbol at the command's conclusion to avoid synchronous behavior. Consequentially, it raises concerns regarding its propriety as a suitable method for achieving asynchronous execution.

Subprocess: A Superior Solution

In lieu of os.system(), the subprocess module offers a more appropriate solution in the form of the Popen class. This class enables the seamless execution of long-running commands asynchronously, allowing the Python script to continue its operation while the external command performs its tasks.

Implementation

To illustrate the usage of Popen, consider the following example:

<code class="python">from subprocess import Popen

# Initiate the long-running 'watch ls' command
p = Popen(['watch', 'ls'])

# Continue executing the Python script while the command runs
# ...

# Terminate the subprocess when necessary
p.terminate()</code>

Additional Capabilities

Beyond asynchronous execution, the Popen instance offers several other capabilities. Notably, it allows for the monitoring of its execution status through the poll() method. Additionally, one can leverage the communicate() method to exchange data via stdin and await the termination of the process.

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