UNIX for Dummies Questions & Answers

I need help on how I can accomplish my task. I hope someone can help me since I've researching and trying to accomplish this for hours now. Basically, I need to comment-out (or insert a # sign in the beginning of the line) a line when the line has the specific word I am searching. Example I have this line:

On line 2 & 4, the word SOAC (this is what I am searching for) appears, now I need the whole line be commented out just like below:

then, I also need another code to reverse the effect, that is if the line has the word SOAC, it will remove the # sign at the beginning of the line. Thanks in advance for those who can help me!

To replace...

Code:

sed -i '/SOAC/s/^/#/' file1

To reverse...

Code:

sed -i '/SOAC/s/^#//' file1

Assuming you have GNU sed with -i option to modify the file in place.

To replace the first time

Code:

perl -i -pe 's/^([^\#].*?SOAC)/#$1/' file

Reverse Process

Code:

perl -i -pe 's/^\#(.*?SOAC)/$1/' file

Code:

awk '/SOAC/ {$0="#"$0}1' infile