pyenv/libexec/rbenv-version-name

#!/usr/bin/env bash
set -e
[ -n "$RBENV_DEBUG" ] && set -x

if [ -z "$RBENV_VERSION" ]; then
  RBENV_VERSION_FILE="$(rbenv-version-file)"
  RBENV_VERSION="$(rbenv-version-file-read "$RBENV_VERSION_FILE" || true)"
fi

if [ -z "$RBENV_VERSION" ] || [ "$RBENV_VERSION" = "system" ]; then
  echo "system"
  exit
fi

RBENV_VERSION_PATH="${RBENV_ROOT}/versions/${RBENV_VERSION}"

if [ -d "$RBENV_VERSION_PATH" ]; then
  echo "$RBENV_VERSION"
else
  echo "rbenv: version \`$RBENV_VERSION' is not installed" >&2
  exit 1
fi