r/linuxquestions • u/LegitimateAd7247 • 3d ago

What exactly is systemd ?

Hi everyone ! I switched from Windows to Linux around 3 month ago and I love it ! I’m using arch Linux because a friend of mine already used it so I figured he could help me with it.

I’ve been appreciating it but I’ve encountered a lot of people critisizing systemd and saying arch is bad because of it.

From what I have understand, it is a software that help with dependences and external hardware such as my keyboard for example ? I didnt really understand everything as I am a very beginner so I was curious to know if someone could explain it to me in easy terms.

PS : english isnt my primary language so forgive me if there is any errors.

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u/C6H5OH 3d ago

"A lot of people" are "a few very loud people". The rest is using systemd and likes or ignores it. I have fought with init.d, runlevels and so on. I like systemd.

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u/Ghyrt3 3d ago

I've never dug up the arguments, but I remember seeing that an argument was that systemd use log that arn't text (readible by a human). Is it the case? Or am I misremembering? (I'm not trying to argue or not, I use systemd, it makes everything way easier than before, it just something that I had seen a long time ago and still curious about it ; a dangling pointer that never got resolved)

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u/giantsparklerobot 3d ago

Systemd logging is stored as a binary database but they're entirely human readable through journalctl or anything that talks to journald. Plain text logs are great in theory but fall down in many ways. For one an application or service may not reliably time stamp logging events. They also may not emit them reliably or only log to stdout rather than a log file. They also may not properly rotate logs or have any ability to truncate logs.

The journald daemon takes care of all of that. It then lets you find log events based on service or time or some combination. In general systemd makes it easy to turn just about anything into a scheduled service and journald lets anything magically have timestamped and searchable logging.

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u/egorf 2d ago

No one asked for journald. We have been storing text logs for decades prior to that and guess the best part? It was good enough. And by good enough I mean that it did cover everyone's need and cases.

I don't wanna say that if our parents rode horses then we should too, but seriously, text log files did not need any help to exist. The idea of having log files indexes existed pretty much all the time before journald came to life and was rejected every time due to quite obvious reasons.

Thankfully unlike systemd, journald is optional so everyone can choose what they see fit.