UNIX for Dummies Questions & Answers

Hi,

I have the following file:

--#
--#line1
--#line2
--#line3
--#
--#line4
--#line5

and I want to use something like:

sed 's/--#/newline/g' file > newfile

to substitute the lines containing only '--#', but when I try, it replaces every instance of '--#' with 'newline' and I want to keep the lines with text after '--#'!

Does that make sense?

Can anyone help!?

Try this:

Code:

sed s/^--#$/newline/ file > newfile

Regards.

Thanks that worked great!

Is there any method of apply this to only the second line containing only '--#' and leaving the first line the same?

Thanks for your help!

Code:

sed "2{s/^--#$/newline/;}" file > newfile

Thank you, that works on the first occurence if i change the 2 at the start to a 1, but it doesnt work on the 2nd occurence if it is left as a 2!

Im not sure why!

Oh I see, it works if I change the number to 9 (The line number of the second '--#'.

But I have many files and the 2nd occurnce of '--#' occurs on different lines in each file.

Is there anyway to applu the command to the second occurence instead of specifying a line number?

Ok,
Ive found out what I need to do, I need to expand the pattern space to include the entire file (not just one line), then search for the nth occurence of '--#'.

Does anyone know how to do this?

Ive tried this:
sed -n -e H -e '${' -e g -e 's/--#/newline/2' -e p -e \} file > newfile

and this:
sed -n -e H -e '${' -e g -e 's/^--#$/newline/2' -e p -e \} file > newfile

The first one changes the second line, but when i added the ^ and $ in the second one, nothing happens!

Can anyone help!!?