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linux:classnotes:rh124:system_processes

Identify Automatically Started System Processes

Systemd

Replaces the older and clunkier init. Default as of RH7. Manages various things

Services Daemons
Path watches files
Mount controls mounts
Timer scheduling
Slice resource management
socket listens to ports
target groups units

YOu can see the processes using pstree -p

Systemd divives your system into manageable chunks to see them

 systemcctl list-units 

You can specify to just list a particular type

 systemctl list-units -t services -a 

the -a will showe all se3rvices including those not active or installed that systemd knows about

You can also check if a service is enabled and or activbe with

 systemctl is-active service name

If a service is not enabled you can enable it and start it with one command

 systemctl enable --now service-name

List the enabled or disabled states of all service units.

 systemctl list-unit-files --type=service 

working with services

Every service has a process ID you can see it using systemctl or you can try using

 pidof service

this will show you all the process ids associated with that service. Ussually the lowest one is the main one and others are branches.

reload

you can reload a service to cause it to reread the configuration file. This does not affect the PID ofr aq service those stay the same

restart

this restarts the service and it gets a new PID

if you are unsure if you can reload a service you can try the

 systemctl reload-or-restarrt service 

first tries a reload if tht does not work it will relstart it

ypu can also list the dependencies of a service

 systemctl list-dependencies service 

you can also see what calls the service with the

--reverse 

option

The system can also mask a service so it will not run even to satisfy a dependency

 systemctl mask service 
linux/classnotes/rh124/system_processes.txt · Last modified: by 127.0.0.1