I was having a discussion on the CB about how to reduce overheads with very large files where the area of interest is just a small part of the file Found solution to some but not to all Case 1: Last 100 lines of the file(total 1000000 lines) is of interest. Solution use tail -100 on the file and process Also if end of line is what interests, File::ReadBackwards is there. But the problem which I could not find a solution to is this. I have a file which has 1000000 lines, but the area of interest is only after the certain regexp is found in the file. Standard solution 
open FH, "file";
while (<FH>) {
  last if /regexp/;
}
while (<FH>) {
  do something;
}

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Now in the above case suppose I know the exact line number at which the regexp occurs, what I could do is a tail ($length - $line.no) and process the file. But if I dont then the above solution will not work. Also I was thinking If I know that the regexp occurs near the end of the file I cound use a readbackwards to get the file pointer till that regexp point and then start parsing the file. For that I need to know if there is a way to take the pointer to a certain line number. For example If I want while(<FH) {} to start parsing from line no 10000, how to do that?

In reply to Handling large files by tsk1979

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