Looking for a regular expression for this...

[John Machin]

malahal at us.ibm.com wrote:
> Hi,
>     My string is a multi line string that contains "filename
>     <filename>\n" and "host <host>\n" entries among other things.
>
>     For example: s = """ filename X
>                     host hostname1
>                     blah...
>                     host hostname2
>                     blah...
>                     filename Y
>                     host hostname3
>                     """
> Given a host name, I would like to get its filename (The closest
> filename reading backwards from the host line). I could read each line
> until I hit the host name, but I am looking for an RE that will do job.

Looking for? REs don't lurk in the undergrowth waiting to be found. You
will need to write one (unless some misguided person spoon-feeds you).
What have you tried so far?

> The answer should be "Y" for host hostname3 and "X" for either host
> hostname1 or hostname2.
> 
> Thanks in advance.
> 
> --Malahal.