pyenv/libexec/rbenv-path

#!/usr/bin/env bash -e

if [ -n "$1" ]; then
  RBENV_VERSION="$1"
elif [ -z "$RBENV_VERSION" ]; then
  RBENV_VERSION="$(rbenv-version)"
fi

RBENV_VERSION_PATH="${HOME}/.rbenv/versions/${RBENV_VERSION}"
if [ ! -d "$RBENV_VERSION_PATH" ]; then
  echo "rbenv: version \`${RBENV_VERSION}' not installed" >&2
  exit 1
fi

echo "$RBENV_VERSION_PATH"