Command to insert lines before first match

Question

I have file with the below info

testing
testing
testing

I want to insert a word(tested) before the first testing word using sed or any linu

Answer 1

Exactly:

sed '0,/testing/s/testing/tested\n&/' file

For lines containing "testing":

sed '0,/.*testing.*/s/.*testing.*/tested\n&/' file

For Lines Starting with "testing"

sed '0,/^testing.*/s/^testing.*/tested\n&/' file

For lines ending with "testing":

sed '0,/.*testing$/s/.*testing$/tested\n&/' file

To update the content of the file with the result add "-i", example:

sed -i '0,/testing/s/testing/tested\n&/' file