LINUX: How To Make Updated/Modified/New sysctl Kernel Parameter Changes In /etc/sysctl.conf File Get Into Affect/Load On Linux Without A Reboot? (sysctl command)

Below sysctl commands can be used to make updated/modified/new sysctl kernel parameter changes inside /etc/sysctl.conf file to get into affect or load on Linux host without a reboot.

sysctl -p

or

sysctl -p /etc/sysctl.conf

Products to which Article Applies

All Linux Operating Systems

Additional Reference

https://linux.die.net/man/8/sysctl

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LINUX: How To Display All Runtime Kernel Parameters In Linux? (sysctl command)

Below sysctl command can be used to display all runtime kernel parameters in Linux.

sysctl -a

Below is portion of "sysctl -a" command output for reference.

# sysctl -a
abi.vsyscall32 = 1
crypto.fips_enabled = 0
debug.exception-trace = 1
debug.kprobes-optimization = 1
dev.hpet.max-user-freq = 64
dev.mac_hid.mouse_button2_keycode = 97
dev.mac_hid.mouse_button3_keycode = 100
dev.mac_hid.mouse_button_emulation = 0

Products to which Article Applies

All Linux Operating Systems

Additional Reference

https://linux.die.net/man/8/sysctl

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LINUX: How To Check Which Services Are Enabled on Linux Machine? ("systemctl" command)

Below "systemctl" Command can be used to check all the services enabled on Linux machine.

systemctl list-unit-files 

Below is example snippet of above command.

UNIT FILE                                     STATE

tmp.mount                                     disabled
var-lib-nfs-rpc_pipefs.mount                  static
brandbot.path                                 enabled
systemd-ask-password-console.path             static
systemd-ask-password-wall.path                static
session-2.scope                               static
acpid.service                                 enabled

Products to which Article Applies

All Linux Operating Systems

Additional References

https://www.digitalocean.com/community/tutorials/how-to-use-systemctl-to-manage-systemd-services-and-units

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LINUX: How To Enable Particular Service Using "systemctl" Command To Auto Start During Reboot?

Below "systemctl" Command can be used to enable particular Service.

systemctl enable <service name>

For example if you want to enable Docket service to start when Linux Machine reboots, your "systemctl" command will look as follows:

systemctl enable docker

Once the service is enable run below command to verify that the service is enabled.

systemctl list-unit-files | grep -i <service>

For e.g. if you enabled Docker service, you can run below command to verify whether the Docker service is enabled.

systemctl list-unit-files | grep -i docker.

Below is example output of above command.

# systemctl list-unit-files | grep -i docker
docker.service          enabled

Products to which Article Applies

All Linux Operating Systems

Additional References

https://www.digitalocean.com/community/tutorials/how-to-use-systemctl-to-manage-systemd-services-and-units

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LINUX: How to Enable Service On Linux Nodes Using Systemctl Command? (How To Doc)

On Linux 7 & above versions "chkconfig --list" command cannot be used for enabling the services.
We will have to use systemctl command to check and enable services on Linux 7 and above versions.

Follow below steps to enable the desired service on Linux OS using systemctl command.

1. Check the status of the service using below command.

systemctl list-unit-files | grep -i <service name>

Below is sample output which shows the status of docker as disabled.

# systemctl list-unit-files | grep -i docker

docker.service                                disabled

docker.socket                                 disabled

2. Enable the desired service using below command.

systemctl enable docker

Below is sample snippet of enabling the docker service using systemctl command.

# systemctl enable docker

Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service.

3. Check the status of the service using below command.

systemctl list-unit-files | grep -i <service name>

You will see that the service is enabled. Below is the sample output which shows docker service as being enabled.

# systemctl list-unit-files | grep -i docker

docker.service                                enabled

docker.socket                                 disabled

Products to which Article Applies

All Host Operating Systems Using ILOM

Additional Reference

https://www.digitalocean.com/community/tutorials/how-to-use-systemctl-to-manage-systemd-services-and-units

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LINUX: How To List All the Services and their State Using systemctl command? (How To Doc)

On Linux 7 & above versions "chkconfig --list" command does not list all th systemd services and their status.

We will have to use systemctl command to check the services and their status on Linux 7 and above versions.

Below command can be executed to list all the services and their status.

systemctl list-unit-files

Below is sample output. 

UNIT FILE                                     STATE

proc-sys-fs-binfmt_misc.automount             masked

dev-hugepages.mount                           static

dev-mqueue.mount                              static

proc-fs-nfsd.mount                            static

proc-sys-fs-binfmt_misc.mount                 static

sys-fs-fuse-connections.mount                 static

sys-kernel-config.mount                       static

sys-kernel-debug.mount                        static

tmp.mount                                     disabled

var-lib-nfs-rpc_pipefs.mount                  static

brandbot.path                                 enabled

systemd-ask-password-console.path             static

systemd-ask-password-wall.path                static

session-2.scope                               static

acpid.service                                 enabled

arp-ethers.service                            disabled

auth-rpcgss-module.service                    static

Products to which Article Applies

All Linux Operating Systems

Additional Reference

https://www.digitalocean.com/community/tutorials/how-to-use-systemctl-to-manage-systemd-services-and-units

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