sed use: expected context address

Question

I use the sed command on macOS with the following text:

$ cat pets.txt 
This is my cat
  my cat\'s name is betty
This is your dog
  your dog\'s name         


        

Answer 1

Mac OS X uses BSD sed and not GNU sed.

When you use a GNU sed extension with Mac OS X sed, you get different results, or failures.

Classically, sed does not support numeric offsets, forwards or backwards. You'll need to revise your script to work on Mac OS X.

This would work on the given data, but the use of fish is suspect:

sed '/dog/,/your fish/s/^/# /g' pets.txt