Python中的错误和警告处理

Question

I'm trying to make a script that handles errors and warnings from other scripts, it can be other python or bash scripts.

The only way I found to do this is by using Popen, I execute the script using Popen and store the stderr into a variable.

Checking the returncode of Popen I can say if the stderr is a warning (returncode 0, the script ran successfully) or if it is in fact an error (returncode 1, the script did not run successfully).

But there are some scripts that even with error they continue the commands and so the returncode is 0 like it was some warning or the script did run successfully. How can I handle this sort of thing?

Here are some samples to get a full understanding:

sshpass -p password sftp -q username@host << EOF
cd Export
get file.csv
EOF

This bash script gives me an error that it cannot find the file.csv, ok.

File "/Export/file.csv" not found.

This python script executes the script above.

script = 'bash_script'
proc = subprocess.Popen("bash {}.sh ".format(script), stderr=subprocess.PIPE, shell=True)
(stdout, stderr) = proc.communicate()
if (proc.returncode) and (stderr != ''):
      print("\n[ERROR]:\n" + str(stderr))
elif (not proc.returncode) and (stderr != ''):
      print("\n[WARNING]:\n" + str(stderr))
else # (not proc.returncode) and (stderr == '')
      print("\n[SUCCESS]\n")

But executing the script above I get:

[WARNING]:
File "/Export/file.csv" not found

When it should be:

[ERROR]:
File "/Export/file.csv" not found

This happens because the returncode is 0 and the error went to stderr as expected.

How can I handle this case? What is the best way to diferentiate errors from warnings? Why the sftp command is returning 0 when it should be returning 1 which corresponds to an error?

Answer 1

Instead of trying to do this entirely from python, I suggest you implement logging in the bash scripts. In python, you can simply read the error from the logs like:

fault = ""
error = ""
warning = ""
with open('log.txt','r') as f:
    x = f.readline()
    if 'error' in x.lower():
       fault = "error"
       error = x
       print("The type is {} and it says:\n {}".format(fault,error))
    elif 'warning' in x.lower():
       fault = "warning"
       warning = x
       print("The type is {} and it says:\n {}".format(fault,warning))