sed与特定字符串一致

Question

I am having trouble with sed utility. I have to substitute regex with a string but only on lines which contains another specific string. Whats more I have to read from file and then modify it by sed , not only export substitute values. Here is what I have tried:

sed -e '`grep aa test`"s/aa/xx/g test'

sed -n '/aa/p' test | sed s/aa/xx/g

grep aa test | sed 's/aa/xx/g'

Answer 1

Use an adress before s command :

sed '/aa/ s/aa/xx/g' test

s command will only apply on lines containing the address pattern

But there is no need to have the same pattern in address and in s command.

A better example would be :

sed '/bb/ s/aa/xx/g' test