RHCE7 -- systemctl命令

查询所有单元的状态:

[root@rhce7 ~]# systemctl 

UNIT                                                  LOAD   ACTIVE SUB       DESCRIPTION

proc-sys-fs-binfmt_misc.automount                     loaded active waiting   Arbitrary Executable File Formats File System Automoun

sys-devices-pci00...get1:0:0-1:0:0:0-block-sr0.device loaded active plugged   VBOX_CD-ROM

sys-devices-pci0000:00-0000:00:03.0-net-enp0s3.device loaded active plugged   PRO/1000 MT Desktop Adapter

sys-devices-pci00...0-0000:00:05.0-sound-card0.device loaded active plugged   82801AA AC'97 Audio Controller

sys-devices-pci0000:00-0000:00:08.0-net-enp0s8.device loaded active plugged   PRO/1000 MT Desktop Adapter

sys-devices-pci00...0:0-2:0:0:0-block-sda-sda1.device loaded active plugged   VBOX_HARDDISK

sys-devices-pci00...0:0-2:0:0:0-block-sda-sda2.device loaded active plugged   LVM PV ewUQqv-N1i5-9xcA-GRad-2BLV-qOTh-vNPOd2 on /dev/

sys-devices-pci00...get2:0:0-2:0:0:0-block-sda.device loaded active plugged   VBOX_HARDDISK

sys-devices-platform-serial8250-tty-ttyS0.device      loaded active plugged   /sys/devices/platform/serial8250/tty/ttyS0
...

仅查询服务单元的状态:

[root@rhce7 ~]# systemctl --type=service

UNIT                                                   LOAD   ACTIVE SUB     DESCRIPTION

abrt-ccpp.service                                      loaded active exited  Install ABRT coredump hook

abrt-oops.service                                      loaded active running ABRT kernel log watcher

abrt-xorg.service                                      loaded active running ABRT Xorg log watcher

abrtd.service                                          loaded active running ABRT Automated Bug Reporting Tool

accounts-daemon.service                                loaded active running Accounts Service

...

查看处于失败或维护状态的任何单元:

[root@rhce7 ~]# systemctl status rngd.service -l

rngd.service - Hardware RNG Entropy Gatherer Daemon

   Loaded: loaded (/usr/lib/systemd/system/rngd.service; enabled)

   Active: failed (Result: exit-code) since Fri 2015-07-17 11:08:27 CST; 32min ago

  Process: 649 ExecStart=/sbin/rngd -f (code=exited, status=1/FAILURE)

 Main PID: 649 (code=exited, status=1/FAILURE)

   CGroup: /system.slice/rngd.service



Jul 17 11:08:25 rhce7.example.com systemd[1]: Started Hardware RNG Entropy Gatherer Daemon.

Jul 17 11:08:27 rhce7.example.com rngd[649]: Unable to open file: /dev/tpm0

Jul 17 11:08:27 rhce7.example.com rngd[649]: can't open any entropy source

Jul 17 11:08:27 rhce7.example.com rngd[649]: Maybe RNG device modules are not loaded

Jul 17 11:08:27 rhce7.example.com systemd[1]: rngd.service: main process exited, code=exited, status=1/FAILURE

Jul 17 11:08:27 rhce7.example.com systemd[1]: Unit rngd.service entered failed state.

[root@rhce7 ~]# 

查看特定单元是否活动:

[root@rhce7 ~]# systemctl is-active sshd

active

查看特定单元是否已经开启自启动:

[root@rhce7 ~]# systemctl is-enabled sshd

enabled

列出所有已经加载单元的活动状态

[root@rhce7 ~]# systemctl list-units --type=service

UNIT                         LOAD   ACTIVE SUB     DESCRIPTION

abrt-ccpp.service            loaded active exited  Install ABRT coredump hook

abrt-oops.service            loaded active running ABRT kernel log watcher

abrt-xorg.service            loaded active running ABRT Xorg log watcher

abrtd.service                loaded active running ABRT Automated Bug Reporting 

accounts-daemon.service      loaded active running Accounts Service

alsa-state.service           loaded active running Manage Sound Card State (rest

atd.service                  loaded active running Job spooling tools

查看所有单元的已启用和已禁用设置

[root@rhce7 ~]# systemctl list-unit-files --type=service

UNIT FILE                                   STATE   

abrt-ccpp.service                           enabled 

abrt-oops.service                           enabled 

abrt-pstoreoops.service                     disabled

abrt-vmcore.service                         enabled 

abrt-xorg.service                           enabled 

abrtd.service                               enabled 

accounts-daemon.service                     enabled 

alsa-restore.service                        static 

查看失败的服务的状态

[root@rhce7 ~]# systemctl list-unit-files --type=service

UNIT FILE                                   STATE   

abrt-ccpp.service                           enabled 

abrt-oops.service                           enabled 

abrt-pstoreoops.service                     disabled

abrt-vmcore.service                         enabled 

abrt-xorg.service                           enabled 

abrtd.service                               enabled 

accounts-daemon.service                     enabled 

alsa-restore.service                        static 

屏蔽服务
有时候可能安装了互相冲突的服务，比如network和NetworkManager，iptables和firewalld
可以将服务屏蔽。屏蔽将在配置目录中创建链接，使的启动该服务时不发生任何事

[root@rhce7 ~]# systemctl mask network

ln -s '/dev/null' '/etc/systemd/system/network.service'

[root@rhce7 ~]# systemctl unmask network

rm '/etc/systemd/system/network.service'