Python handling specific error codes?
Python handling specific error codes?
Hey I'm wondering how to handle specific error codes. For example, [Errno 111] Connection refused
[Errno 111] Connection refused
I want to catch this specific error in the socket module and print something.
4 Answers
4
If you want to get the error code, this seems to do the trick;
import errno
try:
socket_connection()
except socket.error as error:
if error.errno == errno.ECONNREFUSED:
print(os.strerror(error.errno))
else:
raise
You can look up errno error codes.
errno
ECONNREFUSED
You are absolutely right. I am sure that there are more cases like that.
– Utku Zihnioglu
Mar 1 '11 at 22:48
It's important to have an
else: raise, otherwise all other error codes will be silently ignored!– jtpereyda
Sep 3 '16 at 22:56
else: raise
@AnatolyAlekseev I mean an
else that pairs with the if. So the else would be at the first indent level, within the except block.– jtpereyda
Aug 29 at 3:49
else
if
except
os.strerror(error.errno) will convert the error code to a message string. i.e.: os.strerror(104) returns 'Connection reset by peer'– Jerther
Nov 14 at 14:31
os.strerror(error.errno)
os.strerror(104)
On Unix platforms, at least, you can do the following.
import socket, errno
try:
# Do something...
except socket.error as e:
if e.errno == errno.ECONNREFUSED:
# Handle the exception...
else:
raise
Before Python 2.6, use e.args[ 0 ] instead of e.errno.
e.args[ 0 ]
e.errno
Using
e.errno instead of e.args[0] is usually preferred (for exceptions that use errnos).– Thomas Wouters
Mar 1 '11 at 22:44
e.errno
e.args[0]
I thought that to begin with, but testing it out on my Mac it seemed that
socket.error didn't have an errno member. It turns out that before Python 2.6, socket.error wasn't a subclass of IOError and so didn't have an errno member. But of course, before Python 2.6 the except t as e syntax wasn't valid either... I'll update my code.– jchl
Mar 1 '11 at 23:07
socket.error
errno
socket.error
IOError
errno
except t as e
I'm developing on Windows and found myself in the same predicament. But the error message always contains the error number. Using that information I just convert the exception to a string str(Exception), convert the error code I wanna check for to a string str(socket.errno.ERRORX) and check if the error code is in the exception.
str(Exception)
str(socket.errno.ERRORX)
Example for a connection reset exception:
except Exception as errorMessage:
if str(socket.errno.ECONNRESET) in str(errorMessage):
print("Connection reset")
#etc...
This avoids locale specific solutions but is still not platform independent unfortunately.
This seems hard to do reliably/portably but perhaps something like:
import socket
try:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(('localhost', 4167))
except socket.error, e:
if 'Connection refused' in e:
print '*** Connection refused ***'
which yields:
$ python socketexception.py
*** Connection refused ***
Pretty yucky though.
Why would you say this is unreliable/not portable? What is "yucky" about this?
– Nick Presta
Mar 1 '11 at 22:39
Because I am not 100% sure that the exception message on Windows would have "Connection refused" in it and not something similar but different like "Could not connect". Not sure if those error messages are standardize (e.g.: in POSIX) and besides not all platforms are necessarily POSIX-compliant.
– Marc Abramowitz
Mar 1 '11 at 22:44
(-1) WARNING: This will fail completely in non-english locales.
– sum1stolemyname
Jun 12 '14 at 19:29
Yeah, that's a good point. This will only work in an English locale. All in all, this is a pretty terrible idea and you should use
errno like in the above answers.– Marc Abramowitz
Jun 13 '14 at 23:28
errno
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On OSX,
ECONNREFUSEDappears to be 61 not 111, so hard-coding the value 111 would be a bad idea for portability.– jchl
Mar 1 '11 at 22:46