Understanding haproxy's regex

[Christoph Kukulies]

I have the following line in my config:

backend website
    http-request replace-header Destination ^([^\ :]*)\ /(.*) \1\ /opencms/\2
    server www.mydomain.org 127.0.0.1:8080


Actually I'm used the write multiple patterns as \(pattern1\)\(pattern2\). So 
is it a different regex syntax?

The other question - since I don't understand the above statement at all - what 
does it exactly do?

With 2.4 the corresponding line was (instead of the replace-header):

 reqirep ^([^\ :]*)\ /(.*) \1\ /opencms/\2

Let me try to translate the regex:

substitute 
pattern1:  begin-of-line followed by not blank and not colon repeatedly,
followed by a blank, followed by
pattern2:  any char repeatedly 

by 

<pattern1><blank> /opencms/<pattern2>

But the interspersed space don't make sense to me. spaces in URLs?

Thanks in advance,
--
Christoph

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