Ubuntu 16.04在搭建Redis Cluster搭建时，使用gem install redis时出现：ERROR: While executing gem ... (Gem::FilePermissionError) You don't have write permissions for the /var/lib/gems/2.3.0 directory.

注意：千万不要使用sudo来执行gem install redis。

解决方法：

sudo apt-get update
sudo apt-get install git-core curl zlib1g-dev build-essential libssl-dev libreadline-dev libyaml-dev libsqlite3-dev sqlite3 libxml2-dev libxslt1-dev libcurl4-openssl-dev python-software-properties libffi-dev

cd
git clone https://github.com/rbenv/rbenv.git ~/.rbenv
echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bashrc
echo 'eval "$(rbenv init -)"' >> ~/.bashrc
exec $SHELL

git clone https://github.com/rbenv/ruby-build.git ~/.rbenv/plugins/ruby-build
echo 'export PATH="$HOME/.rbenv/plugins/ruby-build/bin:$PATH"' >> ~/.bashrc
exec $SHELL

rbenv install 2.3.1
rbenv global 2.3.1
ruby -v

最后安装

gem install redis
rbenv rehash

如果不想使用上面的方法，可以使用以下的投机取巧的方法，给上面错误的文件夹增加权限

sudo chmod 777 /var/lib/gems/2.3.0/

sudo chown -R administrator /var/lib/gems

说明：administrator为当前登录的用户，根据实际情况更改。

然后再次执行

gem install redis

参考：

https://gepolv.github.io/ubuntu/ruby/bundler/2016/06/21/gem-install-bundle-issue-on-ubuntu.html