execution – How to stop/terminate a python script from running?

execution – How to stop/terminate a python script from running?

You can also do it if you use the exit() function in your code. More ideally, you can do sys.exit(). sys.exit() which might terminate Python even if you are running things in parallel through the multiprocessing package.

Note: In order to use the sys.exit(), you must import it: import sys

To stop your program, just press Control + C.

execution – How to stop/terminate a python script from running?

If your program is running at an interactive console, pressing CTRL + C will raise a KeyboardInterrupt exception on the main thread.

If your Python program doesnt catch it, the KeyboardInterrupt will cause Python to exit. However, an except KeyboardInterrupt: block, or something like a bare except:, will prevent this mechanism from actually stopping the script from running.

Sometimes if KeyboardInterrupt is not working you can send a SIGBREAK signal instead; on Windows, CTRL + Pause/Break may be handled by the interpreter without generating a catchable KeyboardInterrupt exception.

However, these mechanisms mainly only work if the Python interpreter is running and responding to operating system events. If the Python interpreter is not responding for some reason, the most effective way is to terminate the entire operating system process that is running the interpreter. The mechanism for this varies by operating system.

In a Unix-style shell environment, you can press CTRL + Z to suspend whatever process is currently controlling the console. Once you get the shell prompt back, you can use jobs to list suspended jobs, and you can kill the first suspended job with kill %1. (If you want to start it running again, you can continue the job in the foreground by using fg %1; read your shells manual on job control for more information.)

Alternatively, in a Unix or Unix-like environment, you can find the Python processs PID (process identifier) and kill it by PID. Use something like ps aux | grep python to find which Python processes are running, and then use kill <pid> to send a SIGTERM signal.

The kill command on Unix sends SIGTERM by default, and a Python program can install a signal handler for SIGTERM using the signal module. In theory, any signal handler for SIGTERM should shut down the process gracefully. But sometimes if the process is stuck (for example, blocked in an uninterruptable IO sleep state), a SIGTERM signal has no effect because the process cant even wake up to handle it.

To forcibly kill a process that isnt responding to signals, you need to send the SIGKILL signal, sometimes referred to as kill -9 because 9 is the numeric value of the SIGKILL constant. From the command line, you can use kill -KILL <pid> (or kill -9 <pid> for short) to send a SIGKILL and stop the process running immediately.

On Windows, you dont have the Unix system of process signals, but you can forcibly terminate a running process by using the TerminateProcess function. Interactively, the easiest way to do this is to open Task Manager, find the python.exe process that corresponds to your program, and click the End Process button. You can also use the taskkill command for similar purposes.

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