How to use a bash function in a git alias?

Question

I want to use a bash function in a git alias. So I added this to my .bashrc:

fn() {
    echo \"Hello, world!\"
}
export -f fn

Answer 1

If you want to be 100% certain that exported functions will be honored, ensure that the shell being called is bash, not /bin/sh (which will not honor them if it's implemented by ash or dash).

fn() { echo "hello, world"; }
export -f fn
git config --global alias.fn $'!bash -c \'fn "$@"\' _'
git fn

...properly emits:

hello, world

The relevant entry in .gitconfig:

[alias]
    fn = !bash -c 'fn \"$@\"'