So, you want to write a python program that can exit on command. Well, you’ve come to the right blog!
We’ll start by writing a python program that exits without command. This is the easiest part of exiting a python program.
To do this, we use the sys module. Its pretty simple, just import it at the top of your script, and then create a function using sys.exit().
It’ll look something like this:
import sys
def exit():
sys.exit()
Now, when you call the function exit(), your program will end! It’s that easy! You can even add some sys.argv stuff to make it more convenient for yourself:
import sys
def exit(code):
sys.exit(code)
That way, when you call exit(0), your program will end with no errors! If there are any errors, just change 0 to something greater than 0.
The python exit() method is the way to exit a script in python.
The exit method takes an optional argument, typically an integer, that gives an exit status. The convention is to use 0 for success and non-zero values for error conditions. The reason for having an exit status is that it can be tested in the shell by other programs.
If you run a script and it exits with a non-zero value, then you know there was an error during execution of the script. If you are writing a Python program which needs to print different messages depending on an error code returned by your program, you can use sys.exit() function. The parameter passed to this function will be printed on the screen when the program ends.
How to exit a python script in the middle of execution.
Sometimes, one may wish to exit a program before it ends without error. For example, if a user chooses to cancel or quit a program, it would not be appropriate for an error to occur.
To do this, you can use the sys module’s exit() function.
sys.exit()
This will end the execution of the current script in progress with no errors.
There are many ways to exit a Python program. Here are a few:
sys.exit() — This is the most common way to exit a Python program. It will simply raise the SystemExit exception and your program will stop. You can also pass an integer argument to sys.exit() to indicate an exit status or error level. For example, sys.exit(1) will indicate that the program exited with an error (see below for more details).
os._exit() — This function is more dangerous than sys.exit(). It bypasses all cleanup handlers, including finally statements and does not call os.close() on file handles, therefore it may result in file corruption.
raise SystemExit — This technique is not recommended, but it does work if you need full control over the SystemExit object that is raised, such as setting a custom message or error code (see below for more details).
quit() — This function was added in Python 3.0 as a synonym for sys.exit(), but it raises the SyntaxError exception in Python 2, so you should avoid using it in your programs if you want them to run on both Python 2 and 3 without modification.
Writing a Python program is like running a Python script. So how to exit a Python script? There are two ways to exit a program in python. Let’s see them one by one.
The first way to exit a program is sys.exit(). You can use this method to stop the execution of your program by using the following syntax:
import sys
sys.exit()
This will stop the execution of your program where you call it. For example, if you write this code in line number 10, the execution will stop at line number 10 and will not go to 11 and 12.
There are a few ways to exit a Python script. We will give examples on how to use the sys, os, and import modules to get the job done.
We will also learn how to use the exit() and quit() methods in Python.
Let’s first look at using the os module. This is best done with a while loop. It will run until a condition is met or it meets an exit command:
import os
while True:
line = input(”)
if line == ‘quit’:
break
elif line == ‘exit’:
os._exit(1)
The most fundamental problem with exit() is that the interpreter has no way to know whether any other atexit handlers have already been called. This means that it cannot allow any of those handlers to raise an exception. In addition, there are a lot of places where Python itself calls exit() and where it would be disastrous to let any registered cleanup code prevent the interpreter from exiting.
There are two main ways to solve this problem.
The first is to let the sys module keep track of the handlers that are supposed to be called when the interpreter exits. The exit() function would then reset sys.stderr and sys.stdout to their default values, set a flag (sys._called_from_exit) indicating that it was about to call all of the handlers, and call them. If any of them raised an exception, sys._called_from_exit would be set back to False and an error message would be written to sys.__stderr__ instead of sys.stderr (since the latter may have been changed by something called from an atexit handler). This seems like a perfectly good solution; in fact, I don’t think I’ve ever seen an atexit handler crash on its way out before,