how to modify a particular content in a file

[gowpsg1]

how to modify a particular field of a record in a file where records saved as line by line

[kbw]

If the lines are variable length, you'll need to re-write the file.

[LB]

Thank you for this wonderful post on how we are to properly modify a certain part of a record in some file where the records are each saved on their own lines. It was very informative.

EDIT: Oh, perhaps you meant "how do you" in place of "how to", and you intended a question mark at the end?