第一次接觸Ruby on Rails， mark一下
1.準備環境。
我是直接在cloud上劃拉了一塊地方，用的Ubuntu的系統。
root@haiyu-personal:~# uname -a
Linux haiyu-personal 4.15.0-58-generic #64-Ubuntu SMP Tue Aug 6 11:12:41 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
2.安裝ruby
2.1 設置代理。
我的機器需要設置代理，在文件下 ~/.bashrc 添加：
export http_proxy=http://10.XXX.X.XX:8080
export https_proxy=http://10.XXX.X.XX:8080
記得source 一下生效
2.2 安裝RVM
執行這個即可，但是我這邊設置代理後還是提示網絡不好，鏈接不上“gpg: keyserver receive failed: Connection timed out”
gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3
curl -sSL https://get.rvm.io | bash
網上查了一下可以這樣設置https://askubuntu.com/questions/53146/how-do-i-get-add-apt-repository-to-work-through-a-proxy/102505#102505
直接把代理指定好，執行沒問題
gpg --keyserver-options http-proxy=http://10.xxx.x.xx:8080 --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3
執行好兩條命令後RVM 就安裝好了，可以看到我的版本啦
root@haiyu-personal:~# rvm -v
rvm 1.29.10-next (master) by Michal Papis, Piotr Kuczynski, Wayne E. Seguin [https://rvm.io]
不行的可以source一下讓修改生效，可以試試這個命令
source /usr/local/rvm/scripts/rvm
實在不知道怎麼source的就退出再進來
2.3 安裝Ruby
rvm install 2.5.5
寫你想要的版本，安裝好啦
root@haiyu-personal:~# ruby -v
ruby 2.5.5p157 (2019-03-15 revision 67260) [x86_64-linux]
3 安裝rails
gem install rails -v 5.2.1
好啦，都安裝好啦。
可以新建項目了，使用命令“rails new your_project_name -d mysql”建好你的項目
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基本到這就可以結束了，後面是我自己的項目需要一些包需要手動安裝，有問題不怕，Google。
對於已經存在的項目，點進去，先執行“bundle install”可以自動安裝依賴項
Q1:"An error occurred while installing capybara-webkit (1.15.0), and Bundler cannot continue.
Make sure that `gem install capybara-webkit -v '1.15.0' --source 'http://gem.wft.int.net.nokia.com/'` succeeds before bundling."
S1: https://github.com/thoughtbot/capybara-webkit/wiki/Installing-Qt-and-compiling-capybara-webkit#debian--ubuntu
sudo apt-get update
sudo apt-get install g++ qt5-default libqt5webkit5-dev gstreamer1.0-plugins-base gstreamer1.0-tools gstreamer1.0-x
Q2:"An error occurred while installing charlock_holmes (0.7.6), and Bundler cannot continue.
Make sure that `gem install charlock_holmes -v '0.7.6' --source 'http://gem.wft.int.net.nokia.com/'` succeeds before bundling."
S2:https://askubuntu.com/questions/243645/how-can-i-install-development-libraries-for-icu-le-and-icu-uc
sudo apt-get install libicu-dev
Q3:"An error occurred while installing libxml-ruby (3.1.0), and Bundler cannot continue.
Make sure that `gem install libxml-ruby -v '3.1.0' --source 'http://gem.wft.int.net.nokia.com/'` succeeds before bundling."
S3:https://askubuntu.com/questions/733169/how-to-install-libxml2-in-ubuntu-15-10
sudo apt-get install libxml2-dev
Q4:"An error occurred while installing mysql2 (0.5.2), and Bundler cannot continue.
Make sure that `gem install mysql2 -v '0.5.2' --source 'http://gem.wft.int.net.nokia.com/'` succeeds before bundling."
sudo apt-get install libmysqlclient-dev
Q5：“An error occurred while installing rugged (0.27.2), and Bundler cannot continue.
Make sure that `gem install rugged -v '0.27.2' --source 'http://gem.wft.int.net.nokia.com/'` succeeds before bundling.”
sudo apt-get install cmake
最後“bundle install”成功啦
在你的項目文件夾下執行"rails s",等待啓動吧
後面可以根據需要安裝自己的mysql, redis 等，不贅述。
https://www.percona.com/doc/percona-server/LATEST/installation/apt_repo.html