4 on my linux machine (I checked w/ sed --version).
Currently, I have a myfile.txt with the following content:
--- title: hello author: Jan King foo: bar author: Jan King ---
I know in GNU sed, I can append after the first occurrence of a match if I prepend the sed command with 0,.
So, if I want to insert goodbye after the first occurrence of ---, I can do that:
sed -i '0,/---/a goodbye' myfile.txt
expected/correct result:
--- goodbye title: hello author: Jan King foo: bar author: Jan King ---
But now, I am trying to insert goodbye after the first occurrence of author: Jan King.
However, the following sed command doesn’t work and appends goodbye 3 times, which is not what I want:
sed -i '0,/^author:.*/a goodbye' myfile.txt
incorrect/unexpected result:
--- goodbye title: hello goodbye author: Jan King goodbye foo: bar author: Jan King ---
If I remove 0, from the above sed command, then goodbye is appended twice after author: Jan King:
sed -i '/^author:.*/a goodbye' myfile.txt
expected result:
--- title: hello author: Jan King goodbye foo: bar author: Jan King goodbye ---
So I’m having trouble appending goodbye on first match only of author: Jan King (even though it is fine on first match of ---).
Can someone please explain why my sed command isn’t working? And how to fix it?
Advertisement
Answer
The link you show in the comment is not quite the same command sequence that you’re trying to use. If you want to use the same technique, try:
sed -i '0,/^(author:.*)/s//1nNew Inserted Line/' myfile.txt