RHCE7--systemctl command

To query the status of all cells:

[[Email protected] ~]# systemctl UNIT LOAD ACTIVE SUB descriptionproc-sys-fs-Binfmt_misc.automount loaded active waiting arbitrary executable file Formats file System Automo Unsys-devices-pci00...get1:0:0-1:0:0:0-block-sr0.device Loaded Active plugged vbox_cd-Romsys-devices-pci0000:xx-0000:xx:03.0-net-enp0s3.device loaded active plugged Pro/ +MT Desktop Adaptersys-devices-pci00 ...0-0000:xx:05.0-sound-card0.device loaded active plugged 82801AA AC'The Audio Controllersys-devices-pci0000:xx-0000:xx:08.0-net-enp0s8.device loaded active plugged Pro/ +MT Desktop Adaptersys-devices-pci00 ...0:0-2:0:0:0-block-sda-Sda1.device loaded active plugged Vbox_harddisksys-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_harddisksys-devices-platform-serial8250-tty-ttys0.device Loaded Active PLUGGED/SYS/DEVICES/PLATFORM/SERIAL8250/TTY/TTYS0
...

Querying the status of service units only:

[Email protected] ~]# systemctl--type=serviceunit                                                   LOAD   ACTIVE SUB     descriptionabrt-  Ccpp.service                                      Loaded Active exited  Install ABRT coredump hookabrt-oops.service                                      loaded Active Running ABRT kernel log watcherabrt-xorg.service                                      loaded active running ABRT xorg log watcherabrtd.service< c11/>loaded Active running ABRT automated Bug Reporting toolaccounts-daemon.service                                loaded Active Running Accounts Service ...

To view any cells that are in a failed or maintained state:

[Email protected] ~]# systemctl status Rngd.service-Lrngd.service-Hardware RNG Entropy Gatherer Daemon loaded:loaded (/usr/lib/systemd/system/rngd.service; enabled) Active:failed (Result:exit-code) since Fri -- -- -  One: ,: -CST; 32min ago Process:649Execstart=/sbin/rngd-f (code=exited, status=1/FAILURE) Main PID:649(Code=exited, status=1/FAILURE) CGroup:/system.slice/Rngd.servicejul -  One: ,: -Rhce7.example.com systemd[1]: Started Hardware RNG Entropy Gatherer daemon.jul -  One: ,: -Rhce7.example.com rngd[649]: Unable to open file:/dev/Tpm0jul -  One: ,: -Rhce7.example.com rngd[649]: Can'T Open any entropy sourceJul -  One: ,: -Rhce7.example.com rngd[649]: Maybe RNG device modules is not Loadedjul -  One: ,: -Rhce7.example.com systemd[1]: Rngd.service:main process exited, code=exited, status=1/Failurejul -  One: ,: -Rhce7.example.com systemd[1]: Unit Rngd.service entered failed state. [[Email protected]~]#

To see if a specific cell is active:

is-active sshdactive

To see if a specific cell has been turned on since startup:

is-enabled sshdenabled

Lists the active states of all loaded units

[Email protected] ~]# systemctl list-units--type=serviceunit                         LOAD   ACTIVE SUB     descriptionabrt- Ccpp.service            Loaded active exited  Install ABRT coredump hookabrt-oops.service            loaded Active Running ABRT kernel log watcherabrt-xorg.service            loaded active running ABRT xorg log watcherabrtd.service< c11/>loaded Active running ABRT automated Bug Reporting accounts-daemon.service      loaded active running Accounts Servicealsa-state.service           loaded active running Manage Sound Card State (Restatd.service                  loaded active running JOB spooling tools

View enabled and disabled settings for all cells

[Email protected] ~]# systemctl list-unit-files--type=serviceunit FILE State   ABRT-  Ccpp.service                           enabled ABRT-oops.service                           enabled ABRT-pstoreoops.service                     DISABLEDABRT-vmcore.service                         enabled ABRT-xorg.service                           enabled Abrtd.service                               Enabled accounts-daemon.service                     enabled Alsa-restore.service                        static

To view the status of a failed service

 [[email protected] ~]# systemctl list-unit-files--type=serviceunit FILE State ABRT -ccpp.service enabled ABRT -oops.service enabled ABRT -pstoreoops.service disabledabrt -vmcore.service                               Enabled ABRT -xorg.service enabled Abrtd.service  Enabled accounts -daemon.service enabled Alsa -restore.service static  

Shielding Services
Sometimes conflicting services may be installed, such as network and Networkmanager,iptables and FIREWALLD
You can mask the service. Masking creates a link in the configuration directory so that nothing happens when the service is started

[email protected] ~'/dev/null'/etc/systemd/system/ Network.service'~'/etc/systemd/system/network.service '

RHCE7--systemctl command