One always will need to have two joined blocks of size n in memory, whenever there are no matches anymore which start in the front block one will have to delete it, treat the rear block as new front and read a new rear block from disk.

        loaded Blocks 
|------[++++++|++++++]------|------|---| file
   A      B      C      D      E      F
             <----->
              match

[download]

Actually I'm not sure if joining two strings can be done without needing twice as much memory!

Anyway I don't think going to extremes is a good idea...

Cheers Rolf

In reply to Re^5: use regular expressions across multiple lines from a very large input file by LanX
in thread use regular expressions across multiple lines from a very large input file by rizzy

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