pyenv/libexec/rbenv-versions

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

if [ "$1" = "--bare" ]; then
  hit_prefix=""
  miss_prefix=""
  current_version=""
else
  hit_prefix="* "
  miss_prefix="  "
  current_version="$(rbenv-version-name || true)"
fi

print_version() {
  if [ "$1" == "$current_version" ]; then
    echo "${hit_prefix}$(rbenv-version)"
  else
    echo "${miss_prefix}$1"
  fi
}

# detect if there is system ruby
if RBENV_VERSION=system rbenv-which ruby >/dev/null 2>&1; then
  print_version system
fi

for path in "${RBENV_ROOT}/versions/"*; do
  if [ -d "$path" ]; then
    print_version "${path##*/}"
  fi
done