which2.sh

which2() {
  [ -t 1 ] && {
    case "${BASH##*/}${ZSH_NAME}" in
    (bash)  {
              { [ "`builtin type -t $1 2>/dev/null`" = "builtin" ] >&/dev/null; } && \
              { printf '%s is a shell builtin\n' "$1"; return; }
            }
            {
              { (alias;typeset -f) | \which --tty-only --read-alias --read-functions --show-tilde "$@" >&/dev/null; } && \
              { (alias;typeset -f) | \which --tty-only --read-alias --read-functions --show-tilde "$@" && return $?; }
            }
            {
              { builtin type -a "$@" >&/dev/null; } && \
              { builtin type -a "$@" && return $?; }
            } ;;
    (zsh)   {
              { [ "`builtin whence -w $1`" = "$1: builtin" ] >&/dev/null; } && \
              { printf '%s is a shell builtin\n' "$1"; return; }
            }
            {
              { builtin which "$@" >&/dev/null; } && \
              { builtin which "$@" && return $?; }
            }
            {
              { builtin type -a "$@" >&/dev/null; } && \
              { builtin type -a "$@" && return $?; }
            } ;;
    esac; }
  command -p which "$@"; return $? || return;
}