list all the places in one's PATH where a command might be. More reliable than `whence` in a cross-platform setting

list-paths

#!/usr/bin/env bash
set -euo pipefail

if [ $# -lt 1 ]; then
  printf 'USAGE: list-paths <command>\n' 1>&2
  exit 1
fi
bin="$1"
found=0

for item in ${PATH//:/ }; do
  if [ ! -e "$item" ]; then continue; fi

  if [ -e "$item/$bin" ]; then
    printf '%s\n' "$item/$bin"
    found=1
  fi
  # find "$item" -maxdepth 1 -mindepth 1 -name "${1-*}" -print
done

if [ $found -eq 0 ]; then
  exit 127
fi