Tools for Regular Operations
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Managing system services with systemdIn this section, you will learn how to manage
system services, runtime targets, and all about the service status with systemd. You will also learn how to manage system boot targets and services that should start at system boot.
systemd (which you can learn a bit about at https://www.freedesktop.org/wiki/
Software/systemd/) is defined as ab system daemon that’s used to manage the system. It came as a rework of
how a system boots and starts, and it looks at the limitations related to the traditional way of doing it.
When we think about the system starting, we have the initial
kernel and
ramdisk load and execution, but right after that, services and scripts take control to make filesystems available. This helps prepare the services that provide the functionality we want from our system, such as the following Hardware detection Additional filesystem activation Network initialization (wired,
wireless, and soon Network services (time sync, remote login, printers, network filesystems, and soon User-space setup
However, most of the tools that existed before systemd came into play worked on this in a sequential way, causing the whole boot process (from boot to user login) to become lengthy and be subject to delays.
Traditionally, this also meant we had to wait for the required service to be fully available before the next one that depended
on it could be started, increasing the total boot time.
Some approaches were attempted, such as using
Monit or other tools that allow us to define dependencies, monitor processes, and even recover from failures,
but in general, it was reusing an existing tool to perform other functions, trying to win the race regarding the fastest-booting system.
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