Help: How to capture invalid web page from urllib?

Richard Jones richard at
Mon Oct 15 06:18:35 CEST 2001

On Monday 15 October 2001 13:56, Paul Lim wrote:
> I am trying to open a web page from command line. If the web page is not
> valid, I hope to capture the exception and print an error message and
> exit.
> What I currently have is as below, but I am certain I used the wrong
> class because I did not managed to capture the exception (if any) raise.
> Could someone teach me how to test the validity of a web page, ie
> whether does it exist, can it be open?
> # If web page is entered, check whether it is a valid web page
>  try:
>     inf = urllib.URLopener.http_error_default(sys.argv[1])
>  except IOError:
>     print "Invalid webpage!"
>     print "Usage : ./ http://server-name/path-to-document"
>     sys.exit()

The following should be enough:

>>> try:
...  urllib.urlopen('')
... except IOError:
...  print "Page doesn't exist"
Page doesn't exist


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