Quite easy with regular expression !

So, let’s suppose that your file contains only the simple text, below :

This is
a very
small bunch
of text
to see
if it
works nicely

• Open your file in Notepad++

• Place the caret ( cursor ) on the first line which must be replaced ( Line This is ). This point is IMPORTANT !

• Open the Replace dialog ( Ctrl + H )

• Un-check all the box options ( IMPORTANT )

• SEARCH (?-is).+\R(?=(?:.+\R){2}(.+\R))

• REPLACE $1

• Select the Regular expression search mode

• Click ONCE only on the Replace All button

=> You should get your expected text :

of text
to see
if it
works nicely
to see
if it
works nicely

Then, you just have to get rid of the three last lines which are repeated :

of text
to see
if it
works nicely

In a general way, if you must replace the first line by the line N, use the following generic regex :

• SEARCH (?-is).+\R(?=(?:.+\R){N-2}(.+\R))

• REPLACE $1

And replace the N-2 expression with its appropriate number !

so, for example, the different regex searches, below, may be used :

• (?-is).+\R(?=(?:.+\R){0}(.+\R))

• (?-is).+\R(?=(?:.+\R){1}(.+\R))

• (?-is).+\R(?=(?:.+\R){5}(.+\R))

Best Regards,

guy038

Line 1: This is line 4 before replacing.
Line 2: This is line 5 before replacing.
Line 3: This is line 6 before replacing.
Line 4: This is line 7 before replacing.
Line 5: This is line 8 before replacing.
Line 6: This is line 9 before replacing.
Line 7: This is line 10 before replacing.
Line 8: This is line 11 before replacing.
Line 9: This is line 12 before replacing.
Line 10: This is line 10 before replacing.
Line 11: This is line 11 before replacing.
Line 12: This is line 12 before replacing.