Python Popen and select waiting for a process to terminate or a timeout

Download this blogpost from https://codegive.com in this tutorial, we'll explore how to use the popen class from the subprocess module in python along with the select module to wait for a child process to terminate or set a timeout. this is particularly useful when you need to run an external command or process and want to control how long you're willing to wait for it to complete. before we begin, ensure you have python installed on your system. this tutorial is written for python 3.x. to get started, we need to import the necessary modules: subprocess and select. these modules are included in the python standard library. first, let's create a child process using the popen class. we'll use the subprocess.popen constructor to start the process. for this example, let's start a simple process that sleeps for a few seconds. in this example, we're running the sleep 5 command, which will pause execution for 5 seconds. you can replace it with any other command or script you want to run. now that we have a child process running, we can use the select module to wait for it to complete or set a timeout. the select.select function allows us to monitor file descriptors for specific events, in our case, the termination of the child process. in this code: we specify the file descriptors we want to monitor. in this case, we're interested in the standard output (stdout) and standard error (stderr) of the child process. we set a timeout value (in seconds) to limit how long we're willing to wait for the process to complete. we use select.select to wait for either the file descriptors to become readable (indicating that the process has completed) or the specified timeout to expire. finally, we check whether the process completed successfully or if it exceeded the timeout. here's the complete code example: this code will start the child process, wait for it to complete or timeout, and print a message indicating whether the process completed successfully or not. feel free to replace the 'sleep 5' command with any other command or scr ...

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