安装过程非常简单，就一行代码
npm install pm2 -g
运行完成之后输入：
pm2
问题出来了。。。
No command ‘pm2’ found, did you mean:
Command ‘pm’ from package ‘powerman’ (universe)
Command ‘pmc’ from package ‘linuxptp’ (universe)
Command ‘pmi’ from package ‘powermanagement-interface’ (universe)
Command ‘pms’ from package ‘pms’ (universe)
Command ‘pmw’ from package ‘pmw’ (universe)
Command ‘wm2’ from package ‘wm2’ (universe)
Command ‘pmk’ from package ‘pmk’ (universe)
Command ‘pom2’ from package ‘libpod-pom-perl’ (universe)
pm2: command not found
经过无数次重新安装，其他好多解决方案。都快泪奔了。现在将最终的解决办法分析给大家。
1、安装命令执行完成时候请注意终端输出内容
/opt/node-v6.11.2-linux-x64/bin/pm2 -> /opt/node-v6.11.2-linux-x64/lib/node_modules/pm2/bin/pm2
/opt/node-v6.11.2-linux-x64/bin/pm2-dev -> /opt/node-v6.11.2-linux-x64/lib/node_modules/pm2/bin/pm2-dev
/opt/node-v6.11.2-linux-x64/bin/pm2-docker -> /opt/node-v6.11.2-linux-x64/lib/node_modules/pm2/bin/pm2-docker
/opt/node-v6.11.2-linux-x64/bin/pm2-runtime -> /opt/node-v6.11.2-linux-x64/lib/node_modules/pm2/bin/pm2-runtime
/opt/node-v6.11.2-linux-x64/lib
2、第一行箭头后面部分是（/opt/node-v6.11.2-linux-x64/lib/node_modules/pm2/bin/pm2）PM2的安装目录。
3、编写命令
ln -s /opt/node-v6.11.2-linux-x64/lib/node_modules/pm2/bin/pm2 /usr/local/bin
发现pm2已经可以用了
执行sudo ln -s xxx /usr/local/bin
