Python regex not working

>>> import re
>>> html = '<input type="text" value="http://uploadir.com/u/bb41c5b3" />';
>>> regex = r'http://uploadir.com/u/([^"]+)'
>>> link = re.findall(regex, html)
>>> link
['bb41c5b3']
>>> 

Get in the habit of making all regex patterns with raw strings:

In [16]: re.findall("http://uploadir.com/u/(.*)\b", '<input type="text" value="http://uploadir.com/u/bb41c5b3" />')
Out[16]: []

In [17]: re.findall(r"http://uploadir.com/u/(.*)\b", '<input type="text" value="http://uploadir.com/u/bb41c5b3" />')
Out[17]: ['bb41c5b3']

The difference is due to \b being interpreted differently:

In [18]: '\b'
Out[18]: '\x08'

In [19]: r'\b'
Out[19]: '\\b'

'\b' is an ASCII Backspace, while r'\b' is a string composed of the two characters, a backslash and a b.