Modify Line in File Matching WORD1 and NOT WORD2 (Sed/Awk)

Question

I need to add kernel parameters to lines not already containing them. (Don't want to add it to all lines in case it's already there.)

I've built this awk command to do it in buffer, but having trouble getting it into the file itself since awk lacks the ability to edit in place like sed. (However I can't figure out how to do this type of match with sed.)

awk '/\tkernel/&&!/audit=1/ { print $0" audit=1"; }' /etc/grub.conf

This looks for lines matching "kernel" and NOT "audit=1" (appending " audit=1" as necessary.)

Tagged as sed/awk, but open to other suggestions.

Answer 1

Using sed:

sed -i '/kernel/{/audit=1/!s/$/ audit=1/}' /etc/grub.conf