If the tokens you use to identify the start and end of the block can be guaranteed to not cross line boundaries; line by line discovery is relatively simple:

open INFILE, ...;

my @block;

1 while ( $_ = <INFILE> ) !~ /START TOKEN/;

push @block, $_;

push @block, $_ while ($_ = <INFILE>) !~ /END TOKEN/;

close INFILE;

## Use @block perhaps trimming first and last lines first.

[download]
Of course, that gets a little more complicated if the start token can appear more than once without a matching end token.

If the tokens can span lines then a running buffer should work for most purposes. Ie. Appending new lines to the end and discarding lines from the beginning, once the buffer has achieved the minimum length of the token, and then searching the buffer after each new line is added, until the token is found.

Basically, you need to tell us more about the nature of the start & end tokens before we could help you further.

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In reply to Re: Avoid memory error while extracting text block by BrowserUk
in thread Avoid memory error while extracting text block by wrkrbeee

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