ruby 的rvm 安装失败

curl -sSL https://get.rvm.io | bash -s stable
Downloading https://github.com/rvm/rvm/archive/1.26.11.tar.gz
Downloading https://github.com/rvm/rvm/releases/download/1.26.11/1.26.11.tar.gz.asc
gpg: failed to create temporary file `/home/cky/.gnupg/.#lk0x2518060.cky-pc.29930': 权限不够
gpg: 密钥块资源‘/home/cky/.gnupg/pubring.gpg’：常规错误
gpg: 于 2015年03月31日 星期二 05时52分13秒 CST 创建的签名，使用 RSA，钥匙号 BF04FF17
gpg: 无法检查签名：找不到公钥
Warning, RVM 1.26.0 introduces signed releases and automated check of signatures when GPG software found.
Assuming you trust Michal Papis import the mpapis public key (downloading the signatures).

GPG signature verification failed for '/home/cky/.rvm/archives/rvm-1.26.11.tgz' - 'https://github.com/rvm/rvm/releases/download/1.26.11/1.26.11.tar.gz.asc'!
try downloading the signatures:

    gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3

or if it fails:

    command curl -sSL https://rvm.io/mpapis.asc | gpg --import -

the key can be compared with:

    https://rvm.io/mpapis.asc
    https://keybase.io/mpapis