Are the error_perm and msg in "except error_perm, msg" special?

Question

I'm reading this script. It synchronizes files via FTP.

I'm confused with this statement in line 106

try:
    ...
except error_perm, msg:
    ...

It seems the variables error_perm and msg come from nowhere. When the try part goes wrong, the script halts and fails to go into the except part.

Answer 1

You have the next import on the top of the file:

from ftplib import FTP, error_perm

error_perm is an error class.

statement

except error_perm, msg:

catches any exception with type error_perm and stores exception object in variable msg.