sensible-editor

#!/bin/sh
set -eu

main() {
    # Try to connect to an Emacs server
    if hash emacsclient 2>/dev/null \
            && emacsclient -e 1 > /dev/null
    then exec emacsclient -c "$@"
    fi

    for candidate in "$EDITOR" mg hx kak vim vi nano
    do
        if which "$candidate" >/dev/null 2>/dev/null
        then exec "$candidate" "$@"
        fi
    done

    printf >&2 "E: cannot find a sensible editor\n"
    exit 2
}

main "$@"