I've seen people suggesting sys.exit() in Python. My question is that, is there any other way to exit the execution of current script, I mean termination, with an error.
Something like this:
sys.exit("You can not have three process at the same time.")
Currently my solution would be:
print("You can not have three process at the same time.")
sys.exit()
Calling sys.exit with a string will work. The docs mention this use explicitly:
In particular, sys.exit("some error message") is a quick way to exit a program when an error occurs.
To be more specific this will also result in an exit code of 1:
any other object is printed to stderr and results in an exit code of 1
There are 3 approaches, the first as lvc mentioned is using sys.exit
sys.exit('My error message')
The second way is using print, print can write almost anything including an error message
print >>sys.stderr, "fatal error" # Python 2.x
print("fatal error", file=sys.stderr) # Python 3.x
The third way is to rise an exception which I don't like because it can be try-catch
raise SystemExit('error in code want to exit')
it can be ignored like this
try:
raise SystemExit('error in code want to exit')
except:
print("program is still open")
sys.exit() raises a SystemExit exception. Hence it can also be caught in a try-except block.
You can also raise an error like this:
raise SystemExit('Error: 3 processes cannot run simultaneously.')
One advantage of this approach is that you don't have to import the Python sys module. This works on Linux with Python 3 and Python 2. I have not tested it on Windows or Mac OS.
You have to use import sys first
Then use sys.exit("your custom error message")
There's also a convenience function called exit() in Python, no need to import anything for this.
Here's a simple example:
$ python3 -c "exit('This should work...')" ; echo "exit code: $?"
This should work...
exit code: 1
import sys; sys.exit() or raise SystemExit().