Chapter 9: 服务

Section 9.1: 列出在Ubuntu上运行的服务

要获取系统上的服务列表，你可以运行service --status-all命令，运行的结果如下：

demouser@demohosts:~$ service --status-all
 [ + ]  alsa-utils
 [ - ]  anacron
 [ + ]  apparmor
 [ + ]  apport
 [ + ]  atop
 [ + ]  atopacct
 [ - ]  bluetooth
 [ - ]  console-setup.sh
 [ + ]  cron
 [ + ]  cups
 [ + ]  dbus
 [ + ]  docker
 [ + ]  gdm3
 [ - ]  grub-common
 [ + ]  kerneloops
 [ - ]  keyboard-setup.sh
 [ + ]  kmod
 [ + ]  openvpn
 [ - ]  plymouth
 [ + ]  plymouth-log
 [ + ]  procps
 [ - ]  rsync
 [ - ]  saned
 [ - ]  speech-dispatcher
 [ - ]  spice-vdagent
 [ + ]  ssh
 [ - ]  sssd
 [ + ]  sysstat
 [ - ]  ubuntu-fan
 [ + ]  ufw
 [ + ]  unattended-upgrades
 [ - ]  uuidd
 [ - ]  whoopsie
 [ - ]  x11-common

service --status-all的输出结果列出了 System V 所控制的服务状态。

“+”表示服务正在运行，“-”表示服务已停止。您可以通过service SERVICENAME status 来查看服务的状态，SERVICENAME 为 [ + ] 或者 [ - ] 后面的服务名称。

最近几年的发行版本基本放弃了 system v 改为使用systemd。

Section 9.2: Systemd 服务管理

列出正在运行的服务

systemctl 列出正在运行的服务

demouser@demohosts:~$ systemctl
  UNIT                                                                                             LOA>
  proc-sys-fs-binfmt_misc.automount                                                                loa>
  sys-devices-pci0000:00-0000:00:10.0-host32-target32:0:0-32:0:0:0-block-sda-sda1.device           loa>
  sys-devices-pci0000:00-0000:00:10.0-host32-target32:0:0-32:0:0:0-block-sda-sda2.device           loa>
…… 省略 ……
  update-notifier-download.timer                                                                   loa>
  update-notifier-motd.timer                                                                       loa>

Legend: 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.

227 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.

systemctl --failed 列出运行失败的服务

demouser@demohosts:~$ systemctl --failed
  UNIT LOAD ACTIVE SUB DESCRIPTION

0 loaded units listed.

管理目标（类似于System V中的运行级）

systemctl get-default 获取系统的默认目标

demouser@demohosts:~$ systemctl get-default
graphical.target

systemctl set-default <target-name> 设置系统的默认目标，运行级别常用为：mulit-user.target 多用户有网络和 graphical.target图形化界面。 

demouser@demohosts:~$ systemctl set-default graphical.target
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-unit-files ====
管理系统服务或单元文件需要认证。
Authenticating as: demouser
Password: 
==== AUTHENTICATION COMPLETE ====
Created symlink /etc/systemd/system/default.target → /usr/lib/systemd/system/graphical.target.
==== AUTHENTICATING FOR org.freedesktop.systemd1.reload-daemon ====
Authentication is required to reload the systemd state.
Authenticating as: demouser
Password: 
==== AUTHENTICATION COMPLETE ====

运行时（runtime）管理服务

systemctl start [service-name] 启动一个服务

demouser@demohosts:~$ systemctl start docker
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ====
启动“docker.service”需要认证。
Authenticating as: demouser
Password: 
==== AUTHENTICATION COMPLETE ====

systemctl stop [service-name] 停止一个服务

demouser@demohosts:~$ systemctl stop docker
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ====
停止“docker.service”需要认证。
Authenticating as: demouser
Password: 
==== AUTHENTICATION COMPLETE ====
Stopping 'docker.service', but its triggering units are still active:
docker.socket

systemctl restart [service-name] 重启一个服务

demouser@demohosts:~$ systemctl restart docker
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ====
重新启动“docker.service”需要认证。
Authenticating as: demouser
Password: 
==== AUTHENTICATION COMPLETE ====
demouser@demohosts:~$ systemctl restart docker

systemctl reload [service-name] 请求服务重新加载其配置，在配置文件有修改的时候使用

demouser@demohosts:~$ systemctl reload docker
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ====
重新载入“docker.service”需要认证。
Authenticating as: demouser
Password: 
==== AUTHENTICATION COMPLETE ====

systemctl status [service-name] 显示服务的当前状态

demouser@demohosts:~$ systemctl status docker
● docker.service - Docker Application Container Engine
     Loaded: loaded (/usr/lib/systemd/system/docker.service; enabled; preset: enabled)
     Active: active (running) since Tue 2024-11-05 15:15:06 CST; 5s ago
TriggeredBy: ● docker.socket
       Docs: https://docs.docker.com
   Main PID: 10312 (dockerd)
      Tasks: 10
     Memory: 21.9M (peak: 23.3M)
        CPU: 702ms
     CGroup: /system.slice/docker.service
             └─10312 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock

11月 05 15:15:05 demohosts dockerd[10312]: time="2024-11-05T15:15:05.368545637+08:00" level=info msg=">
11月 05 15:15:06 demohosts dockerd[10312]: time="2024-11-05T15:15:06.002243724+08:00" level=info msg=">
11月 05 15:15:06 demohosts dockerd[10312]: time="2024-11-05T15:15:06.209206517+08:00" level=warning ms>
11月 05 15:15:06 demohosts dockerd[10312]: time="2024-11-05T15:15:06.209337426+08:00" level=info msg=">
11月 05 15:15:06 demohosts dockerd[10312]: time="2024-11-05T15:15:06.233515356+08:00" level=warning ms>
11月 05 15:15:06 demohosts dockerd[10312]: time="2024-11-05T15:15:06.233547627+08:00" level=warning ms>
11月 05 15:15:06 demohosts dockerd[10312]: time="2024-11-05T15:15:06.233572887+08:00" level=info msg=">
11月 05 15:15:06 demohosts dockerd[10312]: time="2024-11-05T15:15:06.233644909+08:00" level=info msg=">
11月 05 15:15:06 demohosts dockerd[10312]: time="2024-11-05T15:15:06.282569011+08:00" level=info msg=">
11月 05 15:15:06 demohosts systemd[1]: Started docker.service - Docker Application Container Engine.

管理服务的自动启动

systemctl is-enabled [service-name] 显示指定的服务当前是否设置为系统启动时自启动：

  • enabled ：自启动状态
  • disabled ：非自启动状态
demouser@demohosts:~$ systemctl is-enabled docker
enabled

systemctl is-active [service-name] 显示指定的服务当前是否活动（正在运行）

  • active
  • inactive
demouser@demohosts:~$ systemctl is-active docker
active

systemctl enable [service-name] 启用该服务在系统启动时自启动

demouser@demohosts:~$ sudo systemctl enable docker
Synchronizing state of docker.service with SysV service script with /usr/lib/systemd/systemd-sysv-install.
Executing: /usr/lib/systemd/systemd-sysv-install enable docker
Created symlink /etc/systemd/system/multi-user.target.wants/docker.service → /usr/lib/systemd/system/docker.service.

systemctl disable [service-name] 在系统启动时禁用该服务自启动

demouser@demohosts:~$ sudo systemctl disable docker
Synchronizing state of docker.service with SysV service script with /usr/lib/systemd/systemd-sysv-install.
Executing: /usr/lib/systemd/systemd-sysv-install disable docker
Removed "/etc/systemd/system/multi-user.target.wants/docker.service".
Disabling 'docker.service', but its triggering units are still active:
docker.socket

屏蔽/注销服务

systemctl mask [service-name] 屏蔽/注销服务（被屏蔽/注销的服务无法使用start、stop、anable等操作）

demouser@demohosts:~$ sudo systemctl mask docker
Created symlink /etc/systemd/system/docker.service → /dev/null.

systemctl unmask [service-name] 取消服务的屏蔽/注销

demouser@demohosts:~$ sudo systemctl unmask docker
Removed "/etc/systemd/system/docker.service".

重启systemd

systemctl daemon-reload

demouser@demohosts:~$ systemctl daemon-reload
==== AUTHENTICATING FOR org.freedesktop.systemd1.reload-daemon ====
Authentication is required to reload the systemd state.
Authenticating as: demouser
Password: 
==== AUTHENTICATION COMPLETE ====