regex module, or don't work as expected

[Fredrik Lundh]

Fabian Holler wrote:

> Yes thats right, but that isn't my problem.
> The problem is in the "(?=(iface)|$)" part.

no, the problem is that you're thinking "procedural string matching from 
left to right", but that's not how regular expressions work.

> I have i.e. the text:
> 
> "auto lo eth0
> <MATCH START>iface lo inet loopback
> bla
> blub
> 
> <MATCH END>iface eth0 inet dhcp
>          hostname debian"
> 
> 
> My regex should match the marked text.
> But it matchs the whole text starting from iface.

which is perfectly valid, since a plain "+" is greedy, and you've asked 
for "iface lo" followed by some text followed by *either* end of string 
or another "iface".  the rest of the string is a perfectly valid string.

if you want a non-greedy match, use "+?" instead.

however, if you just want the text between two string literals, it's 
often more efficient to just split the string twice:

     text = text.split("iface lo", 1)[1].split("iface", 1)[0]

</F>