Split file content strings by dash using xargs

Question

I need to read a file and split every line into a domain and a application string

domain.com-backend
domain.com-frontend

For each line I need to call a docker build command (echo just to see the command):

cat $FILE | grep '-' | xargs -I {} echo docker build -t {full} -f apps/{domain}/{application}/Dockerfile .

So in the example I would expect the output

docker build -t domain.com-backend -f apps/domain.com/backend/Dockerfile .
docker build -t domain.com-frontend -f apps/domain.com/frontend/Dockerfile .

Answer 1

You can do it with this loop:

while read -r x; do
    echo docker build -t "$x" -f "apps/${x/-/\/}/Dockerfile" .
done < "$FILE"

Remove echo after testing.

See more for bash parameter expansion

---

In case you want to first filter the file, e.g. there are more lines into there and you want first to grep "-" like in your example, you could use this syntax (bash only):

while read -r x; do
    echo docker build -t "$x" -f "apps/${x/-/\/}/Dockerfile" .
done < <(grep "-" "$FILE")