http://www.linuxe.cn/post-371.html
https://blog.csdn.net/lonnng2004/article/details/88964763
** 配置文件存放于/usr/lib/systemd/system/，设置开机启动后会在/etc/systemd/system目录建立软链接文件**
\\~shell
[root@mongo-mms system]# cat mongod-appdb.service
[Unit]
Description=MongoDB Database Server
Documentation=https://docs.mongodb.org/manual
After=network.target
[Service]
User= mongod
Group=mongod
Environment=“OPTIONS=-f /etc/mongodb-mms/app.conf”
ExecStart=/usr/bin/mongod $OPTIONS
PermissionsStartOnly=true
PIDFile=/data/mms-mongodb/app/run/app.pid
Type=forking
Restart=always
RestartSec=30s
# file size
LimitFSIZE=infinity
# cpu time
LimitCPU=infinity
# virtual memory size
LimitAS=infinity
# open files
LimitNOFILE=64000
# processes/threads
LimitNPROC=64000
# locked memory
LimitMEMLOCK=65536
# total threads (user+kernel)
TasksMax=infinity
TasksAccounting=false
# Recommended limits for for mongod as specified in
# http://docs.mongodb.org/manual/reference/ulimit/#recommended-settings
[Install]
WantedBy=multi-user.target
\\~