Export

Function

If you in ZSH, then first run bash -l to make sure that you define and export the function in Bash before using it in a Bash subshell.

foo () {
  echo 'Foo'
}

foo
# Foo
echo $(foo)
# Foo

Export and use it in a subshell:

$ export -f foo
$ bash -c foo
Foo

Example use-case:

$ export -f foo
$ find . -name README.md -exec bash -c 'foo $0' '{}' \;
Foo