vagrantのゲストOS上でrails アプリケーションの骨格が作れない。

joushima-no-MacBook-Pro:aaa joshima$ vagrant init bbb
A Vagrantfile has been placed in this directory. You are now
ready to vagrant up your first virtual environment! Please read
the comments in the Vagrantfile as well as documentation on
vagrantup.com for more information on using Vagrant.
joushimaryouta-no-MacBook-Pro:aaa joshima$ vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
==> default: Importing base box 'bbb'...
==> default: Matching MAC address for NAT networking...
==> default: Setting the name of the VM: aaa_default_1450170504946_82847
==> default: Clearing any previously set forwarded ports...
==> default: Clearing any previously set network interfaces...
==> default: Preparing network interfaces based on configuration...
default: Adapter 1: nat
==> default: Forwarding ports...
default: 22 => 2222 (adapter 1)
==> default: Booting VM...
==> default: Waiting for machine to boot. This may take a few minutes...
default: SSH address:
default: SSH username: vagrant
default: SSH auth method: private key
default: Warning: Connection timeout. Retrying...
default: Warning: Connection timeout. Retrying...
default:
default: Vagrant insecure key detected. Vagrant will automatically replace
default: this with a newly generated keypair for better security.
default:
default: Inserting generated public key within guest...
default: Removing insecure key from the guest if it's present...
default: Key inserted! Disconnecting and reconnecting using new SSH key...
==> default: Machine booted and ready!
==> default: Checking for guest additions in VM...
default: The guest additions on this VM do not match the installed version of
default: VirtualBox! In most cases this is fine, but in rare cases it can
default: prevent things such as shared folders from working properly. If you see
default: shared folder errors, please make sure the guest additions within the
default: virtual machine match the version of VirtualBox you have installed on
default: your host and reload your VM.
default:
default: Guest Additions Version: 4.3.28
default: VirtualBox Version: 5.0
==> default: Mounting shared folders...
default: /vagrant => /Users/joshima/aaa
joushima-no-MacBook-Pro:aaa joshima$ vagrant ssh
Last login: Thu Jul 16 08:48:31 2015 from 10.0.2.2
Welcome to your Vagrant-built virtual machine.
[vagrant@localhost ~]$ echo "Hi"
Hi
[vagrant@localhost ~]$ rails new aaa
-bash: rails: コマンドが見つかりません
[vagrant@localhost ~]$ ls
base.sh cleanup.sh puppet.sh vagrant.sh virtualbox.sh zerodisk.sh
[vagrant@localhost ~]$ rails new ccc
-bash: rails: コマンドが見つかりません
[vagrant@localhost ~]$
vagrantのゲストOS上でrails アプリケーションの骨格が作れない。
プログラミング初心者で何がおかしいすらわかりません。
よろしくお願いいたします。