[SOLVED] How to add a prefix to all lines that don't start with one of multiple words

Issue

I am trying to add a prefix to all the lines in a file that don't start with one of multiple words using sed.

Example :

someText
sleep 1
anotherString
sleep 1
for i in {1..50}
do
command
sleep 1
secondCommand
sleep 1
done

Should become

PREFIX_someText
sleep 1
PREFIX_anotherString
sleep 1
for i in {1..50}
do
PREFIX_command
sleep 1
PREFIX_secondCommand
sleep 1
done

I am able to exclude any line starting with a single pattern word (ie: sleep, for, do, done), but I don't know how to exclude all lines starting with one of multiple patterns. Currently I use the following command :

sed -i '/^sleep/! s/^/PREFIX_/'

Which works fine on all the lines starting with sleep. I imagine there is some way to combine pattern words, but I can't seem to find a solution. Something like this (which obviously doesn't work) :

sed -i '/[^sleep;^for;^do]/! s/^/PREFIX_/'

Any help would be greatly appreciated.

Solution

Use alternation with multiple words for negation:

sed -i -E '/^(sleep|for|do)/! s/^/PREFIX_/' file

PREFIX_someText
sleep 1
PREFIX_anotherString
sleep 1
for i in {1..50}
do
PREFIX_command
sleep 1
PREFIX_secondCommand
sleep 1
done

/^(sleep|for|do)/! will match all lines except those that start with sleep, or for or do words.

Answered By - anubhava

Answer Checked By - David Marino (WPSolving Volunteer)