一、官方文档：
官方相关文档：http://pm2.keymetrics.io/docs/usage/startup/#generating-a-startup-script
二、具体操作过程如下：
1、生成开机启动 pm2 服务的配置文件
运行：pm2 startup 命令
➜ ~ pm2 startup
[PM2] Init System found: systemd
[PM2] To setup the Startup Script, copy/paste the following command:
sudo env PATH=$PATH:/home/user1/.nvm/versions/node/v8.8.1/bin /home/user1/.nvm/versions/node/v8.8.1/lib/node_modules/pm2/bin/pm2
startup systemd -u user1 --hp /home/user1
粘贴上面的命令到终端，如下：
➜ init.d sudo env PATH=$PATH:/home/user1/.nvm/versions/node/v8.8.1/bin /home/user1/.nvm/versions/node/v8.8.1/lib/node_modules/pm2/bin/pm2
startup systemd -u user1 --hp /home/user1
[sudo] user1 的密码：
在非root用户下会让你输入密码。密码输入完成后终端会出现如下内容：
PM2] Init System found: systemd
Platform systemd
Template
[Unit]
Description=PM2 process manager
Documentation=https://pm2.keymetrics.io/
After=network.target [Service]
Type=forking
User=user1
LimitNOFILE=infinity
LimitNPROC=infinity
LimitCORE=infinity
Environment=PATH=/home/user1/.nvm/versions/node/v8.8.1/bin:/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
Environment=PM2_HOME=/home/user1/.pm2
PIDFile=/home/user1/.pm2/pm2.pid ExecStart=/home/user1/.nvm/versions/node/v8.8.1/lib/node_modules/pm2/bin/pm2 resurrect
ExecReload=/home/user1/.nvm/versions/node/v8.8.1/lib/node_modules/pm2/bin/pm2 reload all
ExecStop=/home/user1/.nvm/versions/node/v8.8.1/lib/node_modules/pm2/bin/pm2 kill [Install]
WantedBy=multi-user.target Target path
/etc/systemd/system/pm2-user1.service
Command list
[ 'chmod +x /etc/systemd/system/pm2-user1.service',
'systemctl enable pm2-user1',
'systemctl start pm2-user1',
'systemctl daemon-reload',
'systemctl status pm2-user1' ]
[PM2] Writing init configuration in /etc/systemd/system/pm2-user1.service
[PM2] Making script booting at startup...
>>> Executing chmod +x /etc/systemd/system/pm2-user1.service
[DONE]
>>> Executing systemctl enable pm2-user1
Created symlink from /etc/systemd/system/multi-user.target.wants/pm2-user1.service to /etc/systemd/system/pm2-user1.service.
[DONE]
>>> Executing systemctl start pm2-user1
[DONE]
>>> Executing systemctl daemon-reload
[DONE]
>>> Executing systemctl status pm2-user1
● pm2-user1.service - PM2 process manager
Loaded: loaded (/etc/systemd/system/pm2-user1.service; enabled; vendor preset: disabled)
Active: active (running) since �� -- :: CST; 47ms ago
Docs: https://pm2.keymetrics.io/
Main PID: (PM2 v2.7.2: God)
CGroup: /system.slice/pm2-user1.service
‣ PM2 v2.7.2: God Daemon (/home/user1/.pm2) �� :: izbp14un3b3r5tbimwuxlbz systemd[]: Starting PM2 process manager...
�� :: izbp14un3b3r5tbimwuxlbz pm2[]: [PM2] Resurrecting
�� :: izbp14un3b3r5tbimwuxlbz systemd[]: Started PM2 process manager.
[DONE]
+---------------------------------------+
[PM2] Freeze a process list on reboot via:
$ pm2 save [PM2] Remove init script via:
$ pm2 unstartup systemd
按照提示的命令进行配置就好了。你会在/etc/systemd/system文件夹下看到pm2-user1.service文件
2、pm2 save, 保存当前 pm2 运行的各个应用保存到 /home/user1/.pm2/dump.pm2下，开机重启时读取该文件中的内容启动相关应用。
➜ ~ pm2 save
[PM2] Saving current process list...
[PM2] Successfully saved in /home/user1/.pm2/dump.pm2
3、查看配置是否开启：使用命令：systemctl status pm2-user1.service
➜ system systemctl status pm2-user1.service
● pm2-user1.service - PM2 process manager
Loaded: loaded (/etc/systemd/system/pm2-user1.service; enabled; vendor preset: disabled)
Active: active (running) since �� -- :: CST; 44min ago
Docs: https://pm2.keymetrics.io/
Main PID: (PM2 v2.7.2: God)
CGroup: /system.slice/pm2-user1.service
‣ PM2 v2.7.2: God Daemon (/home/user1/.pm2) �� :: izbp14un3b3r5tbimwuxlbz pm2[]: [PM2] Resurrecting
参考：http://imweb.io/topic/57c8cbb27f226f687b365636
http://www.ruanyifeng.com/blog/2016/03/systemd-tutorial-commands.html