rc/sh/e

#!/usr/bin/env zsh
# YES_ZSH
# NO_BASH
# NO_DASH

e() {
    local editor=(${=EDITOR})
    local running=0

    if [ -n "$MSYSTEM" ]; then
        if ps -f | awk '{print $6}' \
        | grep -o '[^/]*$' | grep -qFx "${editor[1]}"; then
            running=1
        fi
    elif ps -o comm | grep -qFx "${editor[1]}"; then
        running=1
    fi

    if [ $running -eq 1 ]; then
        printf "%s\n" "${editor[1]} is already running" >&2
        read -q '?Continue? [y/N] ' _ || { echo; return; }
        echo
    fi

    if [ $# -eq 0 ] || [ -n "$MSYSTEM" ]; then
        $=EDITOR "$@"
        return
    fi

    local f needroot=0
    for f in "$@"; do
        # easy: file exists, we have write permissions
        [ -w "$f" ] && continue

        # easy: file exists, but no write permissions
        [ -e "$f" ] && { needroot=1; break }

        # hard: file may be in a directory that we can't inspect
        local d="$f"
        while expr index "$d" / >/dev/null; do
            d="${d%/*}"
            # NOTE: this gets weird with the root directory, not sure how to handle
            [ -e "$d" ] && [ ! -w "$d" ] && { needroot=1 && break; }
        done
        [ $needroot -eq 1 ] && break

        # easy: file just doesn't exist
    done

    if [ $needroot -eq 0 ]; then
        $=EDITOR "$@"
    else
        sudo -e "$@"
    fi
}

[ "${SOURCING:-0}" -gt 0 ] || e "$@"