[SOLVED] sed to modify a line and add a commented version of the orginal line

Issue

I have a file containing multiple rows of the following format

[Site "https://sitename.com/8994DX1"]
[Date "1999.11.04"]
...
[Site "https://sitename.com/678489s"]
[Date "2000.12.04"]
...
[Site "https://sitename.com/788Xxz"]
[Date "2020.12.04"]

I want to prepend the original site line with a semi-colon. I want to add a new dummy site line, which has the same sitename every time.

;[Site "https://sitename.com/8994DX1"]
[Site "https://sitename.com/12345"]
[Date "1999.11.04"]
...
;[Site "https://sitename.com/678489s"]
[Site "https://sitename.com/12345"]
[Date "2000.12.04"]
...
;[Site "https://sitename.com/788Xxz"]
[Site "https://sitename.com/12345"]
[Date "2020.12.04"]

In other words, I want to make the original unique sitename a comment, and in a new unvarying sitename.

I found this question which is close, but I haven't managed to modify it to do what I need.

Thanks for any suggestions.

Solution

This sed command should do the trick:

sed -i.bak '
/^\[Site /!b
s/^/;/
a\
[Site "https://sitename.com/12345"]
' file

Answered By - M. Nejat Aydin

Answer Checked By - Pedro (WPSolving Volunteer)