UNIX for Dummies Questions & Answers

Hi all,

I know this question has probably been answered before, but I am struggling with this problem, even after googling a million pages.

In a file named rdmt.conf
I need a single character replaced, the number in the line below

CUR_OC4J_ID=1

It will always appear after CUR_OC4J_ID in the file.

ie replaced by:
CUR_OC4J_ID=2

I need to be able to toggle this value a few times in my script.

I can find the character via a grep:
CUR_OC4J_ID=$(grep CUR_OC4J_ID $SCRIPTDIR/rdmt.conf | cut -d= -f2)

But I cant work out how to replace it.

I have even created some test files. I can use the sed command to replace "hello" with "no" in a file, but when it gets to CUR_OC4J_ID it just spits out text saying the number in which i wanted it replaced to, and then when you look at the file, its not changed. I thought I could make it easier (but not neater) and just find the current value, and replace the whole line because I can put a variable in the sed command......


Any help would be appreciated, I know this is easy, but I have googled forever.

A sed command that doesn't depend on what number is after CUR_OC4J_ID would be the best/neatest solution.

Is this what you're looking for?

Code:

awk -v var="2" 'BEGIN{FS=OFS="="}
/CUR_OC4J_ID/{$2=var}
{print}
' file > newfile

Regards

Alternatively you can also use sed. If your sed knows the -i option you can change the value in the file like this

Code:

newval=2
sed -i "s/\(CUR_OC4J_ID=\).*/\1$newval/" rdmt.conf

otherwise you'd have to use something like this:

Code:

sed "s/\(CUR_OC4J_ID=\).*/\1$newval/" rdmt.conf > rdmt.conf.new && mv -f rdmt.conf.new rdmt.conf

Legends.

My sed didnt have the -i option but I used your second suggestion.

Thanks both of you for responding so quickly.