You're looking for calls to sys.exit(...) (exit(...) calls sys.exit(...)) in the script. The argument to that method is returned to the environment as the exit code.
It's fairly likely that the script is never calling the exit(...) method, and that 0 is the default exit code.
You're looking for calls to sys.exit(...) (exit(...) calls sys.exit(...)) in the script. The argument to that method is returned to the environment as the exit code.
It's fairly likely that the script is never calling the exit(...) method, and that 0 is the default exit code.
From the documentation for sys.exit:
The optional argument arg can be an integer giving the exit status (defaulting to zero), or another type of object. If it is an integer, zero is considered “successful termination” and any nonzero value is considered “abnormal termination” by shells and the like. Most systems require it to be in the range 0-127, and produce undefined results otherwise. Some systems have a convention for assigning specific meanings to specific exit codes, but these are generally underdeveloped; Unix programs generally use 2 for command line syntax errors and 1 for all other kind of errors.
One example where exit codes are used are in shell scripts. In Bash you can check the special variable $? for the last exit status:
me@mini:~$ python -c ""; echo $?
0
me@mini:~$ python -c "import sys; sys.exit(0)"; echo $?
0
me@mini:~$ python -c "import sys; sys.exit(43)"; echo $?
43
Personally I try to use the exit codes I find in /usr/include/asm-generic/errno.h (on a Linux system), but I don't know if this is the right thing to do.
How to throw error and exit with a custom message in python - Stack Overflow
How to get an exit code in Python? - Stack Overflow
Difference between exit(0) and exit(1) in Python - Stack Overflow
Pause a running python script and resume when necessary.
Videos
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")
Enjoy this Full Explanation demo.
import subprocess
result = subprocess.run("C:/Windows/System32/WindowsPowerShell/v1.0/powershell.exe Write-Output 'Hello world!' ", shell=True, capture_output=True) # command to run in powershell using python subprocess module
res = result.returncode # return system-exit code of the command
out = result.stdout # return output of the powershell command
print(f"The output of the command is {out}, The exit code is {res} and the process generated by command is {result}.")
output
The output of the command is b'Hello world!\r\n', The exit code is 0 and the process generated by command is CompletedProcess(args="C:/Windows/System32/WindowsPowerShell/v1.0/powershell.exe Write-Output 'Hello world!' ", returncode=0, stdout=b'Hello world!\r\n', stderr=b'').
EDITED ANSWER : There must be some unhandled exceptions/errors in your exercise, so that it didn't exit with exit code 0 (which means successful execution of your exercise). Add Try at the start of your program and catching the exception at the end as below sample program.
print() function always returns None, so don't try getting return status from print()
import sys
try:
print('hello world') #print('string') - Always returns None
print("Process finished with exit code 0")
sys.exit(0)
except Exception as ex:
print("Error:"+ex)
sys.exit(1)
0 and 1 are the exit codes.
exit(0) means a clean exit without any errors / problems
exit(1) means there was some issue / error / problem and that is why the program is exiting.
This is not Python specific and is pretty common. A non-zero exit code is treated as an abnormal exit, and at times, the error code indicates what the problem was. A zero error code means a successful exit.
This is useful for other programs, shell, caller etc. to know what happened with your program and proceed accordingly.
This determines the exit status of the program when it finishes running (generally, 0 for success and 1 for error).
It is not unique to Python, and the exact effect depends on your operating system and how the program is called (though 99% of the time, if you're just running Python scripts, it doesn't matter).