I would like to know if there is a way of programatically stopping a python script execution without killing the process like we do with this code:
import sys
sys.exit()
It would be the code equivalent to Ctrl+c
4 Answers
Define your own exception,
class HaltException(Exception): pass
and wrap the script in
try:
# script goes here
# when you want to stop,
raise HaltException("Somebody stop me!")
except HaltException as h:
print(h)
# now what?
2 Comments
Santi Peñate-Vera
Thank you for understanding the question, indeed this solves the problem
no_name
You could also wrap your whole code in functions (don't forget the main() and if name == 'main' stuff), then when you want to exit, return a random value
I had this problem while developing a Sublime Text packages. I was trying to stop a Sublime Text Python package, to test something while the package was being reloaded.
If I call sys.exit(), I kill Sublime Text python interpreter and need to restart Sublime Text. But after searching I figured it out the solution is pretty simple, I just need to call raise ValueError(), instead of sys.exit():
import sys
print(sys.path)
sys.exit()
-->
import sys
print(sys.path)
raise ValueError()
This will stop the python script execution right after running print(sys.path). Although it will print a big stack trace. But if you add the instruction sys.tracebacklimit = 1 before raise ValueError(), you reduce the stack trace call to one line:
import sys
print(sys.path)
raise ValueError()
-->
import sys
print(sys.path)
sys.tracebacklimit = 1
raise ValueError()
Related questions:
Comments
Here is what I've found to work -- staying in the interpreter, while stopping a script.
# ------------------------------------------------------------------
# Reset so get full traceback next time you run the script and a "real"
# exception occurs
if hasattr (sys, 'tracebacklimit'):
del sys.tracebacklimit
# ------------------------------------------------------------------
# Raise this class for "soft halt" with minimum traceback.
class Stop (Exception):
def __init__ (self):
sys.tracebacklimit = 0
# ==================================================================
# ... script here ...
if something_I_want_to_halt_on:
raise Stop ()
# ... script continues ...
1 Comment
A. Donda
Of everything I've found, this is the nicest way to quietly stop a script. But, is it possible to get away without the reset code, which I have to put in my script? Can the Exception somehow clean up after itself?
Surely the simplest solution for the OP is raise KeyboardInterrupt?
This produces the same effect as ctrl+C in the terminal but can be called anywhere in the script. No need for import or further definition.
1 Comment
charliebeckwith
Not incorrect, but explaining why in the future is good practice rather than just a one liner for people that might visit this in the future / 4 years ago and today.
raw_input("Press Enter to continue.")orimport pdb; pdb.set_trace().Ctrl+Cthrows aKeyboardInterruptexception, which, if not caught, terminates the process. So I'm not sure howsys.exitis supposed to be much different.