171
What exactly does systemd do?
(lemmy.zip)
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
Community icon by Alpár-Etele Méder, licensed under CC BY 3.0
When you boot up your Linux, it will mount the root file system and start one program. That program is
systemd
. Everything else on your system will be started throughsystemd
or processes thatsystemd
started.That's why it is important, everything else on your system is build on top of it. That's also why it is difficult to replace, if you use something other than
systemd
, you need a completely new set of config files for that other thing or your software might not work properly. Most distributions have given up on that, as it's just more work for a niche audience, and they just requiresystemd
instead.As a regular user you don't really have to care all that much, most stuff
systemd
does will happen automatically in the background and be setup by your distribution. It can still help to get familiar withsystemd
tools likejournalctl
as that's where all your error messages go andsystemctl
is how you start, stop or disable services on your system. If you use something other thansystemd
those tools won't exist and something else will take their place.As for why people don't like
systemd
, it follows the kitchen-sink approach to software and does a lot of things at once. It replaced a whole zoo of smaller utilities like inetd, syslog, cron, atd, ... Some people dislike this loss of modularity, while most the rest are happy that they have one tool that does all of those things well, especially sincesystemd
can do a lot of those tasks better and in a more unified way than previously.This is a good post.
For people new to Linux I just want to point out - for better or for worse this goes against the Unix philosophy.
One thing that people miss - either out of ignorance, or because it goes against the narrative - is that systemd is modular.
One part handles init and services (and related things like mounts and sockets, because it makes sense to do that), one handles user sessions (logind), one handles logging (journald), one handles networking (networkd) etc etc.
You don't have to use networkd, or their efi bootloader, or their kernel install tool, or the other hostname/name resolution/userdb/tmpfiles etc etc tools.
Could one argue that a monolithic kernel such as the Linux kernel also goes against that principle?
Technically the Linux kernel is just an interface with lots of modules
So is systemd. It is definitely modular and I think it has multiple interfaces as well. I’m not sure if you have configure systemd modules like GRUB does.
wow thank you for taking the time and explaining that! I didn't except to learn that today right before bed today or ever. It's these kind of great comments that i come to lemmy for. Just know that i really appreciate it!
Great comment, cleared up a lot of thing, thanks.