Systemd基础篇：systemd vs SysVinit

梦里梦外; 2021-09-07 06:11 411阅读 0赞

Systemd已经基本取代了SysV的Init，这篇文章从几个方面整理一下Systemd与Init的使用上的区别。

# 命令比较: SysVinit vs Systemd #

<table> 
 <thead> 
  <tr> 
   <th>命令用途</th> 
   <th>SysVInit命令</th> 
   <th>Systemd命令</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>服务启动</td> 
   <td>service 服务名 start</td> 
   <td>systemctl start 服务名.service (.service可省略，后同）</td> 
  </tr> 
  <tr> 
   <td>服务停止</td> 
   <td>service 服务名 stop</td> 
   <td>systemctl stop 服务名</td> 
  </tr> 
  <tr> 
   <td>服务重启</td> 
   <td>service 服务名 restart</td> 
   <td>systemctl restart 服务名</td> 
  </tr> 
  <tr> 
   <td>服务重新加载</td> 
   <td>service 服务名 reload</td> 
   <td>systemctl reload 服务名</td> 
  </tr> 
  <tr> 
   <td>服务状态确认</td> 
   <td>service 服务名 status</td> 
   <td>systemctl status 服务名</td> 
  </tr> 
  <tr> 
   <td>服务开机启动设定</td> 
   <td>chkconfig 服务名 on</td> 
   <td>systemctl enable 服务名</td> 
  </tr> 
  <tr> 
   <td>取消服务开机启动设定</td> 
   <td>chkconfig service off</td> 
   <td>systemctl disable 服务名</td> 
  </tr> 
  <tr> 
   <td>确认服务开机启动设定状态</td> 
   <td>chkconfig 服务名</td> 
   <td>systemctl is-enabled 服务名</td> 
  </tr> 
  <tr> 
   <td>加载服务配置文件</td> 
   <td>chkconfig 服务名 -add</td> 
   <td>systemctl deamon-reload</td> 
  </tr> 
  <tr> 
   <td>关机</td> 
   <td>halt</td> 
   <td>systemctl halt</td> 
  </tr> 
  <tr> 
   <td>关机（电源）</td> 
   <td>poweroff</td> 
   <td>systemctl poweroff</td> 
  </tr> 
  <tr> 
   <td>重启</td> 
   <td>reboot</td> 
   <td>systemctl reboot</td> 
  </tr> 
  <tr> 
   <td>休眠</td> 
   <td>pm-hibernate</td> 
   <td>systemctl hibernate</td> 
  </tr> 
  <tr> 
   <td>挂起</td> 
   <td>pm-suspend</td> 
   <td>systemctl suspend</td> 
  </tr> 
 </tbody> 
</table>

# RunLevel: SysVinit vs Systemd #

<table> 
 <thead> 
  <tr> 
   <th>RunLevel</th> 
   <th>SysVInit</th> 
   <th>Systemd</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>System halt</td> 
   <td>0</td> 
   <td>runlevel0.target, poweroff.target</td> 
  </tr> 
  <tr> 
   <td>Single user mode</td> 
   <td>1</td> 
   <td>runlevel1.target, rescure.target</td> 
  </tr> 
  <tr> 
   <td>Multi user</td> 
   <td>2</td> 
   <td>runlevel02target, multi-user.target</td> 
  </tr> 
  <tr> 
   <td>Multi user with network</td> 
   <td>3</td> 
   <td>runlevel3.target, multi-user.target</td> 
  </tr> 
  <tr> 
   <td>Experimental</td> 
   <td>4</td> 
   <td>runlevel4.target, multi-user.target</td> 
  </tr> 
  <tr> 
   <td>Multi user with network, graphical mode</td> 
   <td>5</td> 
   <td>runlevel5.target, graphical.target</td> 
  </tr> 
  <tr> 
   <td>Reboot</td> 
   <td>6</td> 
   <td>runlevel6.target, reboot.target</td> 
  </tr> 
 </tbody> 
</table>

# 日志确认方式 #

## SysVinit方式 ##

*  确认系统日志文件

> 文件名： /var/log/message  
> 文件名：/var/log/syslog

## Systemd ##

*  确认系统日志信息

> 使用命令： journalctl -f

*  确认某一时间点之后的日志信息

> 使用命令：journalctl -since=xxx

# Systemd特殊命令 #

## 确认启动时间 ##

> 使用命令：systemd-analyze 或者 systemd-analyze time

[root@host ~]# systemd-analyze
    Startup finished in 1.638s (kernel) + 1.951s (initrd) + 14.177s (userspace) = 17.767s
    [root@host ~]# 
    [root@host ~]# systemd-analyze time
    Startup finished in 1.638s (kernel) + 1.951s (initrd) + 14.177s (userspace) = 17.767s
    [root@host ~]#

## 停止服务相关进程 ##

> 使用命令：systemctl kill 服务名

## hostname设定 ##

> 使用命令：hostnamectl

[root@host shell]# hostnamectl
       Static hostname: host.localdomain
             Icon name: computer-vm
               Chassis: vm
            Machine ID: d27a659b15fc379d24204584d5c051bd
               Boot ID: 3fe84ed9506248b9a41c492ca543748a
        Virtualization: kvm
      Operating System: CentOS Linux 7 (Core)
           CPE OS Name: cpe:/o:centos:centos:7
                Kernel: Linux 4.10.4-1.el7.elrepo.x86_64
          Architecture: x86-64
    [root@host shell]# 
    [root@host shell]# 
    [root@host shell]# hostnamectl set-hostname liumiaocn
    [root@host shell]#

再次登录之后，hostname的变化即可看到

[root@liumiaocn ~]#

## 时间设定 ##

> 使用命令： timedatectl

注：使用方法可参看：

*  [https://liumiaocn.blog.csdn.net/article/details/88408155][https_liumiaocn.blog.csdn.net_article_details_88408155]

## 管理login：loginctrl ##

> 使用例：查看当前登录用户的Session状况

[root@liumiaocn ~]# loginctl
       SESSION        UID USER             SEAT            
            10          0 root                             
    
    1 sessions listed.
    [root@liumiaocn ~]#

# 管理locale：localectl #

> 使用例：查看当前本地化设定信息

[root@liumiaocn ~]# localectl
       System Locale: LANG=en_US.UTF-8
           VC Keymap: us
          X11 Layout: us
    [root@liumiaocn ~]#

[https_liumiaocn.blog.csdn.net_article_details_88408155]: https://liumiaocn.blog.csdn.net/article/details/88408155