centos开机自检及开机自启服务-Dash.shell及Systemd方法
目录
centos开机自检及开机自启服务-Dash.shell及Systemd方法
一、基本命令
二、开机登录的过程及开机自启的方法和代码
2.1、 基本过程简单概括
2.1.1、 是否云服务Docker环境镜像自动挂载
2.1.2、设备及其内核驱动挂载检测
2.1.3、挂载root
2.1.4、挂载内核态各文件系统进程并挂载内置root用户运行级别及内核跟踪
2.1.5、加载打印调度模块
2.1.6、用户登录请求及验证
2.1.7、遍历用户态进程或服务的init初始化配置
2.1.8、进入用户会话session
2.1.9、与系统启动的“用户态进程”关联的最后几个关键Target
2.1.10、按各用户态服务配置文件中定义的依赖及其顺序队列化运行服务单元
2.2、 检查用户运行时级别的服务，是否成功开机自启
2.3、附录：开机及登录过程所有服务明细
2.4、检查应用的端口监听状态（关键代码）
2.5、以.sh脚本方式，正确设定开机自启（关键代码）
2.5.1、代码分段测试
2.5.2、用依赖关系合并配置代码
2.6、以.service服务配置文件的方式，正确设定开机自启（关键代码）
2.6.1、启动mongodMyShared.service服务配置 （关键代码）
2.6.2、在终端执行脚本启动eggServer（关键代码）
2.7、mongoDB官方公布的“退出码”
附录：systemctl命令格式
继上篇： 《Linux部署node.JS、NginX、egg、MongoDB和非js世界的后端服务之CentOS-腾讯云》，让我们来看看，在此基础上如何做“开机自启服务”。
现如今的Linux系统，已非过去老的基于sysV的系统及其系统管理了，sysytemd为sysV的替代品，需要重新认识和学习。
sysytemd的各项参数、执行及结果，都是通过systemctl命令行工具来完成的。journalctl命令行工具实现日志功能。
systemctl命令行工具的主要作用：
1、options选项：Query or send control commands to the systemd manager.
以下为各类命令：
2、Unit Commands
3、Unit File Commands
4、Machine Commands
5、Job Commands
6、Environment Commands
7、Manager Lifecycle Commands
8、System Commands
我们学习、使用sysytemd，主要就应当从上述8大类入手实操。
一、基本命令
# 列出当前系统“内存”中，所有loaded启动、active激活、sub底级别的系统或用户服务单元
units及状态：
systemctl
# 列出当前的系统“内存”中，所有服务单元units，包括“死的”或“空的”：
systemctl --all
# 列出已安装的服务单元units：
systemctl list-unit-files
#正常loaded启动但未active激活或未能sub的服务单元units：
systemctl --failed
或：
systemctl --state=failed
# LOAD = Reflects whether the unit definition was properly loaded.反映单元定义是否正确加载
# ACTIVE = The high-level unit activation state, i.e. generalization of SUB.高级别单元的激活状态，即SUB的泛化
# SUB = The low-level unit activation state, values depend on unit type.高级别单元的激活状态，值取决于单元类型
二、开机登录的过程及开机自启的方法和代码
2.1、 基本过程简单概括
2.1.1、 是否云服务Docker环境镜像自动挂载
# 如果环境是云服务Docker，会检查镜像是否自动挂载，否则不会执行该项检测
proc-sys-fs-binfmt_misc.automount
2.1.2、设备及其内核驱动挂载检测
# 执行所有sys-devices-*开头的设备检测，比如dvd-rom、虚拟网络设备、virtio/block/vda虚拟块设备的内核驱动、serial***串口节点及设备驱动、pnp即插即用设备、以太网等：
sys-devices-*
# 执行所有系统模块加载：
sys-module-*
# 执行所有子系统的各项检测及加载：
sys-subsystem-*
2.1.3、挂载root
Root Mount 即：_.mount
2.1.4、挂载内核态各文件系统进程并挂载内置root用户运行级别及内核跟踪
# 挂载内核支持的各类File System文件系统，比如：
# ## Huge Pages File System ：大页面文件系统（与虚拟内存有关，比如mongod不建议）
dev-hugepages.mount
# ## POSIX Message Queue File System ：POSIX消息队列文件系统
dev-mqueue.mount
# ## Arbitrary Executable File Formats File System ： AEF格式文件系统
proc-sys-fs-binfmt_misc.mount
# ## FUSE Control File System ：用户空间(或称用户态)文件系统(Filesystem in Userspace)，对这个文件系统进行的读写操作都会被转给用户态的程序来处理。
sys-fs-fuse-connections.mount
# ## Kernel Configuration File System ：内核配置文件系统
sys-kernel-config.mount
# ## RPC Pipe File System ：远程过程调用Remote Produce Call文件系统
var-lib-nfs-rpc_pipefs.mount
# ## Kernel Debug File System ：内核调试文件系统
# 挂载内置root用户的运行级别，比如run/user/0/*当前root用户的运行级别0（运行级别从0~6共7个）：
run-user-0*
# 内核跟踪/sys/kernel/tracing
sys-kernel-tracing.mount
2.1.5、加载打印调度模块
# ## CUPS Scheduler ：模块化开源打印系统，使用 Internet 打印协议 (Internet Printing Protocol, IPP) 作为基础来管理打印机、打印请求和打印队列。CUPS 支持网络打印机浏览和基于 PostScript 打印机描述的打印选项。CUPS还提供了跨越本地网络的公共打印接口
cups.path
2.1.6、用户登录请求及验证
# Forward Password Requests to Plymouth Directory Watch ： 将登录页面的密码请求及用户输入转发到“Plymouth目录进行监视”的命令行，Plymouth命令转储控制客户端登录
# Forward Password Requests to Wall Directory Watch ：将密码请求转发到“Wall Directory Watch目录进行监视”
2.1.7、遍历用户态进程或服务的init初始化配置
# system and Service Manager ：进入到systemd的作用域，进行系统及其服务管理
# 即：无论是老旧的sysV还是新的systemd，均会在这个环节进入用户态程序的管理
# 老的sysV的init.d下的***.sh文件的函数代码仍然有效，只不过其中的代码必然会大量“冗余”和可能带来“环境依赖”及“主子进程间切换”的不确定性；所以，新的Linux开源标准中，普遍采纳了systemd存储库的发行代码。建议以service配置运行用户态软件的“开机自启”。
init.scope
如果未正确理解系统启动过程中的2.1.6、及2.1.7、这两个步骤及其所处的环境，“开机自启用户态”软件的服务，就是一句空话，是会出错的。
2.1.8、进入用户会话session
session *** of user root或当前登录的用户名 ：开始用户会话管理
2.1.9、与系统启动的“用户态进程”关联的最后几个关键Target
UNIT LOAD ACTIVE SUB
......
sockets.target loaded actived actived
sshd-keygen.target loaded actived activedkeygen.target loaded actived actived
swap.target loaded actived actived
sysinit.target loaded actived actived
timers.target loaded actived actived# .......................................
remote-fs.target loaded actived actived
rpc_pipefs.target loaded actived actived
rpcbind.target loaded actived actived
上述绿色示意的几个Target，分别代表系统与用户边缘接口的内核态：远程文件系统、远程过程调用管道文件系统、远程过程调用的端口绑定。通常它们启动了，你的用户态应用进程，便具备了可启动服务的所有依赖条件。
2.1.10、按各用户态服务配置文件中定义的依赖及其顺序队列化运行服务单元
比如：
UNIT LOAD ACTIVE SUB
● nginx.service loaded actived actived
● mongodMyShared.service loaded failed failed
● eggServerMysite.service loaded failed failed
如果配置的依赖及其队列顺序不正确，可能将导致active激活异常或sub低级别异常。
2.2、 检查用户运行时级别的服务，是否成功开机自启
# 正常loaded挂载但active激活失败的所有服务单元units：
systemctl --failed
或：
systemctl --state=failed
结果：
UNIT LOAD ACTIVE SUB DESCRIPTION
● eggServerMysite.service loaded failed failed eggServer mysite
● mcelog.service loaded failed failed Machine Check Exception Logging Daemon
● mongodMyShared.service loaded failed failed MongoDB Database Server#正常loaded加载但active激活失败且未发出active激活指令或sub指令的所有服务单元units：
systemctl --failed --all
或：
systemctl --state=failed --all
结果，会发现多了一行，dnf-makecache.service ：
UNIT LOAD ACTIVE SUB DESCRIPTION
● dnf-makecache.service loaded failed failed dnf makecache
● eggServerMysite.service loaded failed failed eggServer mysite
● mcelog.service loaded failed failed Machine Check Exception Logging Daemon
● mongodMyShared.service loaded failed failed MongoDB Database Server2.3、附录：开机及登录过程所有单元units明细
# 附录：开机及登录过程所有单元units明细：
#
UNIT LOAD ACTIVE SUB DESCRIPTION
proc-sys-fs-binfmt_misc.automount loaded active running Arbitrary Executable File Formats File System Automount Point
sys-devices-pci0000:00-0000:00:01.1-ata1-host0-target0:0:1-0:0:1:0-block-sr0.device loaded active plugged QEMU_DVD-ROM config-2
sys-devices-pci0000:00-0000:00:05.0-virtio0-net-eth0.device loaded active plugged Virtio network device
sys-devices-pci0000:00-0000:00:06.0-virtio1-block-vda-vda1.device loaded active plugged /sys/devices/pci0000:00/0000:00:06.0/virtio1/block/vda/vda1
sys-devices-pci0000:00-0000:00:06.0-virtio1-block-vda.device loaded active plugged /sys/devices/pci0000:00/0000:00:06.0/virtio1/block/vda
sys-devices-platform-serial8250-tty-ttyS1.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS1
sys-devices-platform-serial8250-tty-ttyS2.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS2
sys-devices-platform-serial8250-tty-ttyS3.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS3
sys-devices-pnp0-00:04-tty-ttyS0.device loaded active plugged /sys/devices/pnp0/00:04/tty/ttyS0
sys-devices-virtual-net-virbr0.device loaded active plugged /sys/devices/virtual/net/virbr0
sys-devices-virtual-net-virbr0\x2dnic.device loaded active plugged /sys/devices/virtual/net/virbr0-nic
sys-module-configfs.device loaded active plugged /sys/module/configfs
sys-module-fuse.device loaded active plugged /sys/module/fuse
sys-subsystem-net-devices-eth0.device loaded active plugged Virtio network device
sys-subsystem-net-devices-virbr0.device loaded active plugged /sys/subsystem/net/devices/virbr0
sys-subsystem-net-devices-virbr0\x2dnic.device loaded active plugged /sys/subsystem/net/devices/virbr0-nic
-.mount loaded active mounted Root Mount
dev-hugepages.mount loaded active mounted Huge Pages File System
dev-mqueue.mount loaded active mounted POSIX Message Queue File System
proc-sys-fs-binfmt_misc.mount loaded active mounted Arbitrary Executable File Formats File System
run-user-0-gvfs.mount loaded active mounted /run/user/0/gvfs
run-user-0.mount loaded active mounted /run/user/0
sys-fs-fuse-connections.mount loaded active mounted FUSE Control File System
sys-kernel-config.mount loaded active mounted Kernel Configuration File System
sys-kernel-debug-tracing.mount loaded active mounted /sys/kernel/debug/tracing
sys-kernel-debug.mount loaded active mounted Kernel Debug File System
sys-kernel-tracing.mount loaded active mounted /sys/kernel/tracing
var-lib-nfs-rpc_pipefs.mount loaded active mounted RPC Pipe File System
cups.path loaded active running CUPS Scheduler
systemd-ask-password-plymouth.path loaded active waiting Forward Password Requests to Plymouth Directory Watch
systemd-ask-password-wall.path loaded active waiting Forward Password Requests to Wall Directory Watch
init.scope loaded active running System and Service Manager
session-11.scope loaded active abandoned Session 11 of user root
session-360.scope loaded active running Session 360 of user root
session-361.scope loaded active running Session 361 of user root
session-362.scope loaded active running Session 362 of user root
session-364.scope loaded active running Session 364 of user root
session-365.scope loaded active running Session 365 of user root
session-416.scope loaded active running Session 416 of user root
session-417.scope loaded active running Session 417 of user root
session-418.scope loaded active running Session 418 of user root
session-419.scope loaded active running Session 419 of user root
session-420.scope loaded active running Session 420 of user root
acpid.service loaded active running ACPI Event Daemon
atd.service loaded active running Job spooling tools
auditd.service loaded active running Security Auditing Service
avahi-daemon.service loaded active running Avahi mDNS/DNS-SD Stack
chronyd.service loaded active running NTP client/server
cloud-config.service loaded active exited Apply the settings specified in cloud-config
cloud-final.service loaded active exited Execute cloud user/final scripts
cloud-init-local.service loaded active exited Initial cloud-init job (pre-networking)
cloud-init.service loaded active exited Initial cloud-init job (metadata service crawler)
crond.service loaded active running Command Scheduler
cups.service loaded active running CUPS Scheduler
dbus.service loaded active running D-Bus System Message Bus
dracut-shutdown.service loaded active exited Restore /run/initramfs on shutdown
● eggServerMysite.service loaded failed failed eggServer mysite
getty@tty1.service loaded active running Getty on tty1
gssproxy.service loaded active running GSSAPI Proxy Daemon
import-state.service loaded active exited Import network configuration from initramfs
iscsi-shutdown.service loaded active exited Logout off all iSCSI sessions on shutdown
kdump.service loaded active exited Crash recovery kernel arming
kmod-static-nodes.service loaded active exited Create list of required static device nodes for the current kernel
ksm.service loaded active exited Kernel Samepage Merging
ksmtuned.service loaded active running Kernel Samepage Merging (KSM) Tuning Daemon
libstoragemgmt.service loaded active running libstoragemgmt plug-in server daemon
lvm2-monitor.service loaded active exited Monitoring of LVM2 mirrors, snapshots etc. using dmeventd or progress polling
● mcelog.service loaded failed failed Machine Check Exception Logging Daemon
ModemManager.service loaded active running Modem Manager
● mongodMyShared.service loaded failed failed MongoDB Database Server
netcf-transaction.service loaded active exited Rollback uncommitted netcf network config change transactions
NetworkManager-wait-online.service loaded active exited Network Manager Wait Online
NetworkManager.service loaded active running Network Manager
nginx.service loaded active running The nginx HTTP and reverse proxy server
nis-domainname.service loaded active exited Read and set NIS domainname from /etc/sysconfig/network
packagekit.service loaded active running PackageKit Daemon
plymouth-quit-wait.service loaded active exited Hold until boot process finishes up
plymouth-quit.service loaded active exited Terminate Plymouth Boot Screen
plymouth-read-write.service loaded active exited Tell Plymouth To Write Out Runtime Data
plymouth-start.service loaded active exited Show Plymouth Boot Screen
polkit.service loaded active running Authorization Manager
qcloud-srv.service loaded active exited Qcloud Configuration Service
rc-local.service loaded active exited /etc/rc.d/rc.local Compatibility
rpc-statd-notify.service loaded active exited Notify NFS peers of a restart
rpcbind.service loaded active running RPC Bind
rsyslog.service loaded active running System Logging Service
serial-getty@ttyS0.service loaded active running Serial Getty on ttyS0
smartd.service loaded active running Self Monitoring and Reporting Technology (SMART) Daemon
sshd.service loaded active running OpenSSH server daemon
sssd.service loaded active running System Security Services Daemon
systemd-fsck-root.service loaded active exited File System Check on Root Device
systemd-journal-flush.service loaded active exited Flush Journal to Persistent Storage
systemd-journald.service loaded active running Journal Service
systemd-logind.service loaded active running Login Service
systemd-machined.service loaded active running Virtual Machine and Container Registration Service
systemd-modules-load.service loaded active exited Load Kernel Modules
systemd-random-seed.service loaded active exited Load/Save Random Seed
systemd-remount-fs.service loaded active exited Remount Root and Kernel File Systems
systemd-sysctl.service loaded active exited Apply Kernel Variables
systemd-tmpfiles-setup-dev.service loaded active exited Create Static Device Nodes in /dev
systemd-tmpfiles-setup.service loaded active exited Create Volatile Files and Directories
systemd-udev-trigger.service loaded active exited udev Coldplug all Devices
systemd-udevd.service loaded active running udev Kernel Device Manager
systemd-update-utmp.service loaded active exited Update UTMP about System Boot/Shutdown
systemd-user-sessions.service loaded active exited Permit User Sessions
tat_agent.service loaded active running tat_agent
tuned.service loaded active running Dynamic System Tuning Daemon
user-runtime-dir@0.service loaded active exited User runtime directory /run/user/0
user@0.service loaded active running User Manager for UID 0
vdo.service loaded active exited VDO volume services
-.slice loaded active active Root Slice
machine.slice loaded active active Virtual Machine and Container Slice
system-getty.slice loaded active active system-getty.slice
system-serial\x2dgetty.slice loaded active active system-serial\x2dgetty.slice
system-sshd\x2dkeygen.slice loaded active active system-sshd\x2dkeygen.slice
system.slice loaded active active System Slice
user-0.slice loaded active active User Slice of UID 0
user.slice loaded active active User and Session Slice
acpid.socket loaded active running ACPID Listen Socket
avahi-daemon.socket loaded active running Avahi mDNS/DNS-SD Stack Activation Socket
cups.socket loaded active running CUPS Scheduler
dbus.socket loaded active running D-Bus System Message Bus Socket
dm-event.socket loaded active listening Device-mapper event daemon FIFOs
iscsid.socket loaded active listening Open-iSCSI iscsid Socket
iscsiuio.socket loaded active listening Open-iSCSI iscsiuio Socket
libvirtd-admin.socket loaded active listening Libvirt admin socket
libvirtd-ro.socket loaded active listening Libvirt local read-only socket
libvirtd.socket loaded active listening Libvirt local socket
lvm2-lvmpolld.socket loaded active listening LVM2 poll daemon socket
rpcbind.socket loaded active running RPCbind Server Activation Socket
sssd-kcm.socket loaded active listening SSSD Kerberos Cache Manager responder socket
systemd-coredump.socket loaded active listening Process Core Dump Socket
systemd-initctl.socket loaded active listening initctl Compatibility Named Pipe
systemd-journald-dev-log.socket loaded active running Journal Socket (/dev/log)
systemd-journald.socket loaded active running Journal Socket
systemd-udevd-control.socket loaded active running udev Control Socket
systemd-udevd-kernel.socket loaded active running udev Kernel Socket
virtlockd.socket loaded active listening Virtual machine lock manager socket
virtlogd.socket loaded active listening Virtual machine log manager socket
basic.target loaded active active Basic System
cloud-config.target loaded active active Cloud-config availability
cloud-init.target loaded active active Cloud-init target
cryptsetup.target loaded active active Local Encrypted Volumes
getty.target loaded active active Login Prompts
local-fs-pre.target loaded active active Local File Systems (Pre)
local-fs.target loaded active active Local File Systems
multi-user.target loaded active active Multi-User System
network-online.target loaded active active Network is Online
network-pre.target loaded active active Network (Pre)
network.target loaded active active Network
nfs-client.target loaded active active NFS client services
nss-user-lookup.target loaded active active User and Group Name Lookups
paths.target loaded active active Paths
remote-fs-pre.target loaded active active Remote File Systems (Pre)
remote-fs.target loaded active active Remote File Systems
rpc_pipefs.target loaded active active rpc_pipefs.target
rpcbind.target loaded active active RPC Port Mapper
slices.target loaded active active Slices
sockets.target loaded active active Sockets
sshd-keygen.target loaded active active sshd-keygen.target
swap.target loaded active active Swap
sysinit.target loaded active active System Initialization
timers.target loaded active active Timers
dnf-makecache.timer loaded active waiting dnf makecache --timer
systemd-tmpfiles-clean.timer loaded active waiting Daily Cleanup of Temporary Directories
unbound-anchor.timer loaded active waiting daily update of the root trust anchor for DNSSEC
# LOAD = Reflects whether the unit definition was properly loaded.
# ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
# SUB = The low-level unit activation state, values depend on unit type.
# 166 loaded units listed.在“腾讯云”的centos8.2镜像下，如何配置开机自动启动服务：
具体应用的案例见本人博文：
Linux部署node.JS、NginX、egg、MongoDB和非js世界的后端服务之CentOS-腾讯云_pulledup的博客-CSDN博客
需要特别说明的是，不同的云服务器服务商，其优化的Linux镜像的实例版本还与云服务器服务商的Docker后端服务有关，它们实现开机自启的脚本和服务的配置，大致方法雷同，但细节各异。
2.4、检查应用的端口监听状态（关键代码）
# 系统以root用户登录后，查看一下端口的侦听状态：
# （1）、web服务器nginx进程
netstat -ntulp | grep 8080
# （2）、mongod进程
netstat -ntulp | grep 27017
# （3）、egg后端服务
netstat -ntulp | grep 7001如果，结果tcp端口处于非监听状态，说明：应用所依赖的服务，并未正确运行，需要先行正确配置。
已经启动，您的“配置”才是正确的：
2.5、以.sh脚本方式，正确设定开机自启（关键代码）
2.5.1、代码分段测试
2.5.1.1、测试nginx的web服务器能否让前端网页跑起来
# web服务器nginx进程：
netstat -ntulp | grep 8080
若正常的话，8080端口承载的前端的前台网页，应该能跑起来：
2.5.1.2、测试mongod及其配置代码是否能让客户端连接成功
# 代码分段测试-测试mongod及其配置代码是否能让客户端连接成功：
sudo /usr/bin/mongod -f /usr/local/mongodb/mongodb.conf &>/dev/null
# 检测mongod的端口是否正常被侦听：
netstat -ntulp | grep 27017
若正常的话，27017端口承载的mongoDB的数据库连接应当正常：
比如vscode下：
比如Navicat下：
2.5.1.3、分段测试egg后端服务的配置代码是否能跑起来
# 分段测试egg后端服务的配置代码是否能跑起来：
cd /usr/local/eggServer/mysite-server-main && npm run initLinux && npm run start >/dev/null 2>&1 &
# 检测egg后端服务的端口是否正常被侦听：
netstat -ntulp | grep 7001
若正常的话，前端的后台网页也会表现正常：
2.5.2、用依赖关系合并配置代码
# 步骤1：
# 任意编辑1个自定义脚本配置文件，比如egg.sh
vim /opt/egg.sh# ###其中加入如下bash shell脚本脚本，启动mongod服务、进入egg服务目录并启动后端的服务脚本：
#!/bin/bash
sudo /usr/bin/mongod -f /usr/local/mongodb/mongodb.conf &>/dev/null &
cd /usr/local/eggServer/mysite-server-main && npm run initLinux && npm run start >/dev/null 2>&1 &
cd
# 步骤2：# bash命令执行自定义的bash shell脚本文件egg.sh，并将其回显重定向输出到/etc/rc.local：
echo "/bin/bash /opt/egg.sh >/dev/null 2>&1 & " >>/etc/rc.local# 再次确认脚本足以拥有能执行它的权限+x ：
chmod +x /etc/rc.d/rc.local
# 步骤3：
# 确认uidgid的有效性（文件/usr/share/doc/setup-*/uidgid为空，即有效，否则清空它）：
vim /usr/share/doc/setup-*/uidgid
# 进入egg后端服务目录，运行后端的服务脚本，并将其回显重定向输出到/etc/profile：
echo "cd /usr/local/eggServer/mysite-server-main && npm run initLinux && npm run start >/dev/null 2>&1 &" >>/etc/profile
# 需要说明的是：
# （1）、以 .service的方式进程守护，来“开机自启”三方应用进程，需要特殊的OS访问权限
# （2）、必须以root身份登录验证后(login.target完成后)，三方应用进程的“开机自启”脚本才能生效；因为mongod的进程 和 egg服务node执行脚本，均需要root权限或预先配置好的授予特殊操作系统用户的足够权限
2.6、以.service服务配置文件的方式，正确设定开机自启（关键代码）
# 需要说明的是：
# （1）、以 .service的方式进程守护，来“开机自启”三方应用进程，需要特殊的OS访问权限
# （2）、必须以root身份登录验证后(login.target完成后)，三方应用进程的“开机自启”脚本才能生效；因为mongod的进程 和 egg服务node执行脚本，均需要root权限或预先配置好的授予特殊操作系统用户的足够权限
2.6.1、启动mongodMyShared.service服务配置 （关键代码）
[Unit]
Description=MongoDB Database Server
Documentation=https://docs.mongodb.org/manual
After=remote-fs.target rpc_pipefs.target rpcbind.target
[Service]
# 下面这个默认选项User=mongod：指操作系统中创建的mongod账号，默认没有设置的，改为root
# #############
User=root
# #############
Group=root
#
# Type=dbus
# BusName=com.mysiteBlog.mongodMyShared
EnvironmentFile=-/usr/bin/mongod
PermissionsStartOnly=true
TimeoutStopSec=35
# 启动前预执行，将:/usr/bin/mongodb目录的宿主改为操作系统用户root：
ExecStartPre=/usr/bin/chown root:root /usr/bin/mongod
ExecStartPre=/usr/bin/chown root:root /usr/local/mongodb/mongod.log
ExecStartPre=/usr/bin/chown root:root /usr/local/mongodb/data/db
ExecStartPre=/usr/bin/chown root:root /tmp/mongodb-27017.sock
# ：这个临时锁定.sock是首次成功启动mongod时产生的，之后它需要权限来访问；但若其它原因它被释放了，应当屏蔽ExecStartPre，否则会抛“文件或文件夹不存在”的异常。
# ###注意，不可将 ExecStartPre= 用于 需要长时间执行的进程。 因为所有由 ExecStartPre= 派生的子进程 都会在启动 ExecStart= 服务进程之前被杀死。
# 启动前预执行，将:/usr/bin/mongodb目录的###访问权限###至少改为755：
ExecStartPre=/usr/bin/chmod -R 777 /usr/bin/mongod
ExecStartPre=/usr/bin/chmod -R 777 /usr/local/mongodb/
ExecStart=/usr/bin/mongod -f /usr/local/mongodb/mongodb.conf
Type=forking
# file size：
LimitFSIZE=infinity
# cpu time：
LimitCPU=infinity
# virtual memory size：
LimitAS=infinity
# open files：
LimitNOFILE=64000
# processes/threads：
LimitNPROC=64000
# locked memory：
LimitMEMLOCK=infinity
# 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
# 中断后自动重启：
Restart=on-abort
# 5秒后重启：
RestartSec=5s
[Install]
WantedBy=multi-user.target
# ：安装服务的文件系统预期的用户界面模式（multi-user.target多用户shell界面目标；graphical.target“图形”界面目标）2.6.2、在终端执行脚本启动eggServer（关键代码）
# 本案，由于egg-Server内部调用连接了mongoDB服务，所以两者之间存在“相互依赖”的“启动”关系：
# 服务中需要配置很复杂的“主进程”、这两个“子进程”相互之间的“上下文切换”，才能完全“开机自启”，
# 我就不再赘述了，又兴趣的，自己去研究：
cd /usr/local/eggServer/mysite-server-main && npm run initLinux && npm run start2.7、mongoDB官方公布的“退出码”
附录：systemctl命令格式
systemctl命令格式：
systemctl [OPTIONS...] {COMMAND} ...Query or send control commands to the systemd manager.
-h --help Show this help
--version Show package version
--system Connect to system manager
--user Connect to user service manager
-H --host=[USER@]HOST
Operate on remote host
-M --machine=CONTAINER
Operate on local container
-t --type=TYPE List units of a particular type
--state=STATE List units with particular LOAD or SUB or ACTIVE state
-p --property=NAME Show only properties by this name
-a --all Show all properties/all units currently in memory,
including dead/empty ones. To list all units installed on
the system, use the 'list-unit-files' command instead.
--failed Same as --state=failed
-l --full Don't ellipsize unit names on output
-r --recursive Show unit list of host and local containers
--reverse Show reverse dependencies with 'list-dependencies'
--job-mode=MODE Specify how to deal with already queued jobs, when
queueing a new job
-T --show-transaction
When enqueuing a unit job, show full transaction
--show-types When showing sockets, explicitly show their type
--value When showing properties, only print the value
--check-inhibitors=MODE
Specify if checking inhibitors before shutting down,
sleeping or hibernating
-i Shortcut for --check-inhibitors=no
--kill-who=WHO Who to send signal to
-s --signal=SIGNAL Which signal to send
--now Start or stop unit in addition to enabling or disabling it
--dry-run Only print what would be done
-q --quiet Suppress output
--wait For (re)start, wait until service stopped again
--no-block Do not wait until operation finished
--no-wall Don't send wall message before halt/power-off/reboot
--no-reload Don't reload daemon after en-/dis-abling unit files
--no-legend Do not print a legend (column headers and hints)
--no-pager Do not pipe output into a pager
--no-ask-password
Do not ask for system passwords
--global Enable/disable/mask unit files globally
--runtime Enable/disable/mask unit files temporarily until next
reboot
-f --force When enabling unit files, override existing symlinks
When shutting down, execute action immediately
--preset-mode= Apply only enable, only disable, or all presets
--root=PATH Enable/disable/mask unit files in the specified root
directory
-n --lines=INTEGER Number of journal entries to show
-o --output=STRING Change journal output mode (short, short-precise,
short-iso, short-iso-precise, short-full,
short-monotonic, short-unix,
verbose, export, json, json-pretty, json-sse, cat)
--firmware-setup Tell the firmware to show the setup menu on next boot
--plain Print unit dependencies as a list instead of a treeUnit Commands:
list-units [PATTERN...] List units currently in memory
list-sockets [PATTERN...] List socket units currently in memory,
ordered by address
list-timers [PATTERN...] List timer units currently in memory,
ordered by next elapse
start UNIT... Start (activate) one or more units
stop UNIT... Stop (deactivate) one or more units
reload UNIT... Reload one or more units
restart UNIT... Start or restart one or more units
try-restart UNIT... Restart one or more units if active
reload-or-restart UNIT... Reload one or more units if possible,
otherwise start or restart
try-reload-or-restart UNIT... If active, reload one or more units,
if supported, otherwise restart
isolate UNIT Start one unit and stop all others
kill UNIT... Send signal to processes of a unit
freeze PATTERN... Freeze execution of unit processes
thaw PATTERN... Resume execution of a frozen unit
is-active PATTERN... Check whether units are active
is-failed PATTERN... Check whether units are failed
status [PATTERN...|PID...] Show runtime status of one or more units
show [PATTERN...|JOB...] Show properties of one or more
units/jobs or the manager
cat PATTERN... Show files and drop-ins of specified units
set-property UNIT PROPERTY=VALUE... Sets one or more properties of a unit
help PATTERN...|PID... Show manual for one or more units
reset-failed [PATTERN...] Reset failed state for all, one, or more
units
list-dependencies [UNIT] Recursively show units which are required
or wanted by this unit or by which this
unit is required or wantedUnit File Commands:
list-unit-files [PATTERN...] List installed unit files
enable [UNIT...|PATH...] Enable one or more unit files
disable UNIT... Disable one or more unit files
reenable UNIT... Reenable one or more unit files
preset UNIT... Enable/disable one or more unit files
based on preset configuration
preset-all Enable/disable all unit files based on
preset configuration
is-enabled UNIT... Check whether unit files are enabled
mask UNIT... Mask one or more units
unmask UNIT... Unmask one or more units
link PATH... Link one or more units files into
the search path
revert UNIT... Revert one or more unit files to vendor
version
add-wants TARGET UNIT... Add 'Wants' dependency for the target
on specified one or more units
add-requires TARGET UNIT... Add 'Requires' dependency for the target
on specified one or more units
edit UNIT... Edit one or more unit files
get-default Get the name of the default target
set-default TARGET Set the default targetMachine Commands:
list-machines [PATTERN...] List local containers and hostJob Commands:
list-jobs [PATTERN...] List jobs
cancel [JOB...] Cancel all, one, or more jobsEnvironment Commands:
show-environment Dump environment
set-environment VARIABLE=VALUE... Set one or more environment variables
unset-environment VARIABLE... Unset one or more environment variables
import-environment [VARIABLE...] Import all or some environment variablesManager Lifecycle Commands:
daemon-reload Reload systemd manager configuration
daemon-reexec Reexecute systemd managerSystem Commands:
is-system-running Check whether system is fully running
default Enter system default mode
rescue Enter system rescue mode
emergency Enter system emergency mode
halt Shut down and halt the system
poweroff Shut down and power-off the system
reboot [ARG] Shut down and reboot the system
kexec Shut down and reboot the system with kexec
exit [EXIT_CODE] Request user instance or container exit
switch-root ROOT [INIT] Change to a different root file system
suspend Suspend the system
hibernate Hibernate the system
hybrid-sleep Hibernate and suspend the system
suspend-then-hibernate Suspend the system, wake after a period of
time and put it into hibernate
