Question

I have a file in the format:

C 1 1 2
H 2 2 1
C 3 1 2
C 3 3 2
H 2 3 1

I need to add ” f” to the end of specific lines, for example the third line, so the output would be:

C 1 1 2
H 2 2 1
C 3 1 2 f
C 3 3 2
H 2 3 1

From Googling, it seems that I need to use sed, but I couldn’t find any examples on how to do specifically what I want.

Thanks in advance.

Answer 1

You are looking for this article on sed. Specifically, the section on restricting to a line number. An example:

sed '3 s/$/f/' < yourFile