[Tutor] Parsing /etc/passwd
hugo.yoshi at gmail.com
Wed Oct 12 15:49:43 CEST 2011
On Wed, Oct 12, 2011 at 3:41 PM, Gerhardus Geldenhuis
<gerhardus.geldenhuis at gmail.com> wrote:
> I wrote the following code:
> f = open('/etc/passwd', 'r')
> users = f.read()
> userelements = re.findall(r'(\w+):(\w+):(\w+):(\w+):(\w+):(\w+):(\w+)',
> print userelements
> for user in userelements:
> (username, encrypwd, uid, gid, gecos, homedir, usershell) = user #
> unpack the tuple into 7 vars
> print username
> but I get no results so my parsing must be wrong but I am not sure why.
> Incidentally while googling I found the
> module http://docs.python.org/library/pwd.html which I will eventually use
> but I am first curious to fix and understand the problem before I throw away
> this code.
the homedir and usershell parts are paths. Paths will contain slashes.
The \w character class captures only [A-Za-z0-9_], that is, letters,
numbers, and the underscore. That means slashes will not match, and so
the entire match fails.
On another note, the structure of the /etc/passwd file is pretty
simple, I don't think you need regexes. Simply use split:
users = f.readlines()
for user in users:
(username, encrypwd, uid, gid, gecos, homedir, usershell) = user.split(':')
More information about the Tutor