Linux Systemctl Tutorial


Hi, today we will learn managing linux services with systemd or systemctl. While linux kernel booting, it loads drivers, mount file systems, starting memory management, creating system calls etc. But after that what? Linux starts an init process to create futher system and user services and processes. To manage system services we need a tool which is generally systemd. With tihs tools we can set a services status, see it.Also we can change mount and system snapshot issues. But we will only look for service management side. By the way a services is a daemon which works background to complete his workloads. Apache, mysql etc are services.

To start a service with a kernel parameter. We change grub configuration and add systemd.unit=sshd which starts sshd service.

To see all running services run systemctl command. As you can se from output systemctl list devies,ttys,services,filessystems

To see status of service use systemctl status. You can see process id traffic info, service name and latest logs.

To start a services use systemctl start httpd. If it starts accordingly it shows nothing as output.

Or to stop httpd

To enable a service start in startup use systemctl enable httpd. It creates a softlink for current initlevel which is multi-user

To disable a service startup systemctl disable httpd

Check a service about enabled status

In linux,unix systems there is two run level which is mostly used. Run level is the status of a system for example if you do not need graphic interface but need networking an multi user you use runlevel3 or multiuser runlevel, if you need gui then you change to runleve 5 or graphical. In these runlevels appropriate services started.

First look current runlevel.

Change to multi user run level which is current

Change to graphical runlevel.

To change default start run level or target

To create a snapshot of current system and services status use systemctl snapshot. This is not disk snapshot just service snapshot. Say you start 25 services  and do not want to do all time you can snapshot this and than easily recall the snapshot. If you want you can give name of the snapshot after snaphot command

Call to the snapshot

To delete existing snapshot

To see service paramaters and details which resides in service file.

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1 Response

  1. 14/10/2017

    […] Linux Systemctl Tutorial […]

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