pyenv/libexec/rbenv-which

#!/usr/bin/env bash -e

RBENV_VERSION="$(rbenv-version)"
RBENV_COMMAND="$1"
RBENV_COMMAND_PATH="${HOME}/.rbenv/versions/${RBENV_VERSION}/bin/${RBENV_COMMAND}"

if [ -x "$RBENV_COMMAND_PATH" ]; then
  echo "$RBENV_COMMAND_PATH"
else
  echo "rbenv: $RBENV_COMMAND: command not found" >&2

  versions="$(rbenv-whence "$RBENV_COMMAND" || true)"
  if [ -n "$versions" ]; then
    { echo
      echo "The \`$1' command exists in these Ruby versions:"
      echo "$versions" | sed 's/^/  /g'
      echo
    } >&2
  fi

  exit 127
fi