"I have figured out a logic ... but I need some help"

In such a case, please UPDATE (and NOT by overwriting your previous) the original node, or add info in a reply to the original node, with a note in the original pointing to the reply.

and, re "seek"

NO; not unless you know the "offset (re which, see above) -- the number of bytes into the file at which your "certain line" begins.

In reply to Re^3: Reading selected portion of a data file by ww
in thread Reading selected portion of a data file by Anonymous Monk

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