[SOLVED] Replace last line of config using bash?

Issue

I have an .env.branch file with the following structure -

SOME_URL=https://somelink.com
SOME_OTHER_URL=https://someotherlink.com
SOME_FLAG=true
SOME_OTHER_OPTION=0
BRANCH_NAME=

My goal is to write a bash script that replaces the BRANCH_NAME config based on an environment variable called BRANCH_NAME (the number of lines in the config isn't fixed). This is how I am currently doing it -

echo "BRANCH_NAME=/"$BRANCH_NAME >> .env.branch

but all this does is append the line every time I run the bash script. So now I have -

SOME_URL=https://somelink.com
SOME_OTHER_URL=https://someotherlink.com
SOME_FLAG=true
SOME_OTHER_OPTION=0
BRANCH_NAME=
BRANCH_NAME=/somebranch
BRANCH_NAME=/somebranch

How can I achieve this using sed or some other bash feature?

Solution

This should replace your last line with whatever new BRANCH_NAME you have, and save it. Just place the line in your bash script or enter it manually. Both work.

sed -i "s/BRANCH_NAME=.*/BRANCH_NAME=${BRANCH_NAME}/" .env.branch

---

Result:

> mkdir sed
> nano .env.branch
> BRANCH_NAME=some_branch
> cat .env.branch 
SOME_URL=https://somelink.com
SOME_OTHER_URL=https://someotherlink.com
SOME_FLAG=true
SOME_OTHER_OPTION=0
BRANCH_NAME=
> sed -i "s/BRANCH_NAME=.*/BRANCH_NAME=${BRANCH_NAME}/" .env.branch
> cat .env.branch 
SOME_URL=https://somelink.com
SOME_OTHER_URL=https://someotherlink.com
SOME_FLAG=true
SOME_OTHER_OPTION=0
BRANCH_NAME=some_branch

Answered By - Nizar

Answer Checked By - Katrina (WPSolving Volunteer)