Sed and replacing one occurence of pattern

Shell Programming and Scripting
1

I would like to use sed to replace one occurence of a pattern in a file. When I use the s/// command it replaces all occurences of the pattern in the file. Should I be using something other than sed?
Thanks

2

One possibility with awk:

awk '/ReplaceWhat/ && !f{sub("ReplaceWhat", "ReplaceWith");f=1}{print}' file

Regards

3

Are you interested in the first or a particular instance of that pattern. Show an example of the input and output data.

4

I am interested in the first instance of the pattern.
example : I want to replace "90 rotate" with "270 rotate"

5

Have you tried my solution?

awk '/90 rotate/ && !f{sub("90 rotate", "270 rotate");f=1}{print}' file
6

how do the quotes work if I want to put it in a system() command?

7

I got it to work thanks