On Tue, Sep 13, 2011 at 3:01 PM, Cyril J. <cyril.varghese.jose / gmail.com> wrote:
>> What exactly are "header lines" in your case?   >> format and your parsing / processing requirements it's difficult to
>> come up with suggestions.
>
> A header line starts with ">"
>
> First Entry, first file:
>>1_4_138_F5-P2
> 234234234234234
>
> First Entry, second file:
>>1_4_138_F3
> 234234234234234
>
> I have two large files(several gigs) that I need to read with a bunch of
> "entries" as the above shown. I need to match the header lines, in this
> case i need to make sure "1_4_138_" is the same in both entries and if
> it is, write those entries with matching headers to new seperate files.

Do you have guaranteed ordering for the header lines in each file?