How to use sed to replace only the first occurrence in a file?

Question

I would like to update a large number of C++ source files with an extra include directive before any existing #includes. For this sort of task, I normally use a small bash s

Answer 1

This might work for you (GNU sed):

sed -si '/#include/{s//& "newfile.h\n&/;:a;$!{n;ba}}' file1 file2 file....

or if memory is not a problem:

sed -si ':a;$!{N;ba};s/#include/& "newfile.h\n&/' file1 file2 file...