How to write value1 || value2 in shell?

Question

I would make a simple script in shell and put a default value in case the user enters nothing. Here is my script:

git add -A
git commit -m "checkpoint commit"
git push

I would make something like

git add -A
git commit -m ($1 || "checkpoint commit")
git push

Answer 1

You can use

git commit -m "${1:-checkpoint commit}"

If $1 is set, ${1:-checkpoint commit} will expand to the value of $1.

If $1 is not set, it will expand to whatever is after the :- (ie "checkpoint commit" in this example).