Linux常用命令-systemctl

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命令

systemctl

描述

Control the systemd system and service manager
系统服务管理

用法

1
systemctl [OPTIONS...] COMMAND [NAME...]

选项

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Options:
     --system         连接系统管理器
  -t --type=TYPE      显示指定类型的单元unit
     --state=STATE    显示指定状态的单元,可选参数LOAD,SUB,ACTIVE
  -p --property=NAME  显示指定名称的属性
  -a --all            显示所有加载的单元或属性
  -l --full           不要省略单元名称
  -r --recursive      递归显示
     --reverse        在使用list-dependencies命令时,仅显示单元之间的反向依赖关系
     --job-mode=MODE  在向任务队列中添加新任务(job)时,如何处理队列中已有的任务
     --show-types     在使用list-sockets命令列出套接字(socket)时,同时显示套接字的类型
  -i --ignore-inhibitors  当关闭或休眠系统时,忽略inhibitor锁
     --kill-who=WHO   配合kill命令使用,指定向哪个进程发送信号
  -s --signal=SIGNAL  指定发送什么信号
     --now            启动或停止单元
  -q --quiet          静默模式
     --no-block       不必等待单元启动/停止完成
     --no-wall        在执行halt/poweroff/reboot之前不发送警告信息
     --no-reload      在完成操作之后不重新加载守护进程
     --no-legend      不显示标题
     --no-pager       不分页
     --no-ask-password  不请求系统密码
     --global         全局开启或关闭单元文件
     --runtime        临时变更,重启后失效
  -f --force          当启用单元文件时,覆盖现有的符号链接,当关闭时,立即执行操作
     --preset-mode=   Apply only enable, only disable, or all presets
     --root=PATH      设置寻找单元文件的根目录
  -n --lines=INTEGER  指定日志显示的行数
  -o --output=STRING  更改journal日志显示格式(short, short-iso,
                              short-precise, short-monotonic, verbose,
                              export, json, json-pretty, json-sse, cat)
     --plain          以列表显示

Unit Commands:
  list-units [PATTERN...]         显示加载的单元
  list-sockets [PATTERN...]       按地址顺序显示加载的socket
  start NAME...                   启动一个或多个单元
  stop NAME...                    停止
  reload NAME...                  重新加载
  restart NAME...                 启动或重启
  try-restart NAME...             如果服务处于启动状态则重启,否则忽略操作
  reload-or-restart NAME...       重新加载或重新启动
  reload-or-try-restart NAME...   重新加载或重新启动
  kill NAME...                    发送信号给一个单元的进程
  is-active PATTERN...            检查单元是否处于活动状态
  is-failed PATTERN...            检查单元是否故障
  status [PATTERN...|PID...]      显示运行状态
  show [PATTERN...|JOB...]        显示单元属性
  cat PATTERN...                  显示单元配置

Unit File Commands:
  list-unit-files [PATTERN...]    列出所有已安装的单元文件及其启用状态
  enable NAME...                  启用
  disable NAME...                 禁用
  reenable NAME...                重新启用
  preset NAME...                  按预设文件重置指定单元状态
  preset-all                      按预设文件重置所有单元状态
  is-enabled NAME...              检查单元是否启用
  mask NAME...                    屏蔽指定单元
  unmask NAME...                  解除屏蔽
  link PATH...                    创建软链接单元文件到标准单元目录中

Manager Lifecycle Commands:
  daemon-reload                   重新加载systemd配置文件

System Commands: 注意以下命令为高危命令
  is-system-running               检查系统是否完全运行
  default                         进入默认模式
  rescue                          进入救援模式
  emergency                       进入紧急模式
  halt                            关闭系统,等同于直接执行halt命令
  poweroff                        关闭系统电源,等同于poweroff命令
  reboot [ARG]                    重启系统,等同于reboot命令
  suspend                         挂起系统
  hibernate                       休眠系统

注意

系统服务脚本路径/usr/lib/systemd/system*,用户服务脚本路径/usr/lib/systemd/user*
在/usr/lib/systemd/system目录下包含了各种unit文件,有service后缀的服务unit,有target后缀的开机级别unit等,service后缀的文件一般包括以下三部分内容[Unit],[Service]和[Install]
参考
http://www.ruanyifeng.com/blog/2016/03/systemd-tutorial-commands.html
http://www.ruanyifeng.com/blog/2016/03/systemd-tutorial-part-two.html

示例

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$ systemctl
UNIT                                    LOAD   ACTIVE SUB       DESCRIPTION
proc-sys-fs-binfmt_misc.automount       loaded active running   Arbitrary Executable File Formats File
sys-devices-pci0000:00-0000:00:10.0-host0-target0:0:0-0:0:0:0-block-sda-sda1.device loaded active plugg
sys-devices-pci0000:00-0000:00:10.0-host0-target0:0:0-0:0:0:0-block-sda-sda2.device loaded active plugg
sys-devices-pci0000:00-0000:00:10.0-host0-target0:0:0-0:0:0:0-block-sda.device loaded active plugged
sys-devices-pci0000:00-0000:00:11.0-0000:02:00.0-net-eth0.device loaded active plugged   82545EM Gigabi
sys-devices-virtual-block-dm\x2d0.device loaded active plugged   /sys/devices/virtual/block/dm-0
sys-devices-virtual-block-dm\x2d1.device loaded active plugged   /sys/devices/virtual/block/dm-1
sys-fs-fuse-connections.mount           loaded active mounted   FUSE Control File System
sys-kernel-config.mount                 loaded active mounted   Configuration File System
systemd-ask-password-plymouth.path      loaded active waiting   Forward Password Requests to Plymouth D
systemd-ask-password-wall.path          loaded active waiting   Forward Password Requests to Wall Direc
rsyslog.service                         loaded active running   System Logging Service
sshd.service                            loaded active running   OpenSSH server daemon
sysstat.service                         loaded active exited    Resets System Activity Logs
systemd-journal-flush.service           loaded active exited    Flush Journal to Persistent Storage
lvm2-lvmpolld.socket                    loaded active listening LVM2 poll daemon socket
systemd-initctl.socket                  loaded active listening /dev/initctl Compatibility Named Pipe
dev-mapper-centos\x2dswap.swap          loaded active active    /dev/mapper/centos-swap
basic.target                            loaded active active    Basic System
...
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.

100 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.
# 显示系统服务状态
$ systemctl list-unit-files
UNIT FILE                                     STATE
proc-sys-fs-binfmt_misc.automount             static
dev-hugepages.mount                           static
dev-mqueue.mount                              static
auditd.service                                enabled
autovt@.service                               enabled
blk-availability.service                      disabled
brandbot.service                              static
...
# 显示系统开启启动的服务
$ systemctl list-unit-files |grep enabled
auditd.service                                enabled
autovt@.service                               enabled
chronyd.service                               enabled
crond.service                                 enabled
...
# 查看指定服务
$ systemctl list-units chronyd.service
UNIT            LOAD   ACTIVE SUB     DESCRIPTION
chronyd.service loaded active running NTP client/server
# 查看系统中所有service类型
$ systemctl list-units --type service
UNIT                               LOAD   ACTIVE SUB     DESCRIPTION
auditd.service                     loaded active running Security Auditing Service
chrony-wait.service                loaded active exited  Wait for chrony to synchronize system clock
chronyd.service                    loaded active running NTP client/server
crond.service                      loaded active running Command Scheduler
dbus.service                       loaded active running D-Bus System Message Bus
getty@tty1.service                 loaded active running Getty on tty1
...
# 显示系统socket
$ systemctl list-sockets
LISTEN                      UNIT                         ACTIVATES
/dev/log                    systemd-journald.socket      systemd-journald.service
/run/dbus/system_bus_socket dbus.socket                  dbus.service
/run/dmeventd-client        dm-event.socket              dm-event.service
/run/dmeventd-server        dm-event.socket              dm-event.service
/run/lvm/lvmetad.socket     lvm2-lvmetad.socket          lvm2-lvmetad.service

# 查看chronyd服务状态
$ systemctl status chronyd
● chronyd.service - NTP client/server
   Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; vendor preset: enabled)
   Active: active (running) since Tue 2021-03-16 13:03:46 CST; 5h 12min ago
     Docs: man:chronyd(8)
           man:chrony.conf(5)
  Process: 670 ExecStartPost=/usr/libexec/chrony-helper update-daemon (code=exited, status=0/SUCCESS)
  Process: 651 ExecStart=/usr/sbin/chronyd $OPTIONS (code=exited, status=0/SUCCESS)
 Main PID: 668 (chronyd)
   CGroup: /system.slice/chronyd.service
           └─668 /usr/sbin/chronyd
Mar 16 15:57:19 centos7 chronyd[668]: Selected source 203.107.6.88
Mar 16 16:03:01 centos7 chronyd[668]: Source 203.107.6.88 offline
Mar 16 16:03:01 centos7 chronyd[668]: Cannot synchronise: no selectable sources
Mar 16 16:03:02 centos7 chronyd[668]: Source 203.107.6.88 online
Mar 16 16:03:02 centos7 chronyd[668]: Selected source 203.107.6.88
# 查看service文件
$ systemctl cat chronyd
# /usr/lib/systemd/system/chronyd.service
[Unit]
Description=NTP client/server
Documentation=man:chronyd(8) man:chrony.conf(5)
After=ntpdate.service sntp.service ntpd.service
Conflicts=ntpd.service systemd-timesyncd.service
ConditionCapability=CAP_SYS_TIME

[Service]
Type=forking
PIDFile=/var/run/chrony/chronyd.pid
EnvironmentFile=-/etc/sysconfig/chronyd
ExecStart=/usr/sbin/chronyd $OPTIONS
ExecStartPost=/usr/libexec/chrony-helper update-daemon
PrivateTmp=yes
ProtectHome=yes
ProtectSystem=full

[Install]
WantedBy=multi-user.target
# 查看属性
$ systemctl show chronyd
Type=forking
Restart=no
PIDFile=/var/run/chrony/chronyd.pid
NotifyAccess=none
RestartUSec=100ms
TimeoutStartUSec=1min 30s
TimeoutStopUSec=1min 30s
WatchdogUSec=0
WatchdogTimestamp=Tue 2021-03-16 13:03:46 CST
WatchdogTimestampMonotonic=3724022
StartLimitInterval=10000000
StartLimitBurst=5
StartLimitAction=none
FailureAction=none

# 重载系统服务
systemctl daemon-reload
# 设置服务开机启动
systemctl enable *.service
# 关闭服务开机启动
systemctl disable *.service
# 启动服务
systemctl start *.service
# 停止服务
systemctl stop *.service
# 重新加载服务
systemctl reload *.service
# 重启服务
systemctl restart *.service

# 可以看到halt,poweroff,reboot命令是systemctl命令的软链接
$ ll /usr/sbin/{halt,poweroff,reboot}
lrwxrwxrwx. 1 root root 16 Jan  7 22:48 /usr/sbin/halt -> ../bin/systemctl
lrwxrwxrwx. 1 root root 16 Jan  7 22:48 /usr/sbin/poweroff -> ../bin/systemctl
lrwxrwxrwx. 1 root root 16 Jan  7 22:48 /usr/sbin/reboot -> ../bin/systemctl
$ ll /usr/bin/systemctl
-rwxr-xr-x. 1 root root 721744 Nov 17 00:47 /usr/bin/systemctl
# 关机
$ poweroff
$ systemctl poweroff

# 服务正常启动状态
$ systemctl start chronyd
$ systemctl status chronyd
● chronyd.service - NTP client/server
   Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; vendor preset: enabled)
# 屏蔽服务,即无法使用systemd管理
$ systemctl stop chronyd
$ systemctl mask chronyd
Created symlink from /etc/systemd/system/chronyd.service to /dev/null.
$ systemctl start chronyd
Failed to start chronyd.service: Unit is masked.
$ systemctl status chronyd
● chronyd.service
   Loaded: masked (/dev/null; bad)
# 解除屏蔽
$ systemctl unmask chronyd
Removed symlink /etc/systemd/system/chronyd.service.
$ systemctl start chronyd