>`cron` works best if you desire simplicity above all else
It may be simple, but it's config file is hard to comprehend compared to a systemd timer. Being able to just use "Friday 17:00" or "hourly" is so much more readable.
It may be simple, but it's config file is hard to comprehend compared to a systemd timer. Being able to just use "Friday 17:00" or "hourly" is so much more readable.
systemctl status foo.timer tells you when it has last triggered and when it will triggered next, if it is still enabled.
systemctl status foo.service tells you if it has been triggered from the timer and when, or ran manually with start
I get the conceptual utter simplicity of cron in place of timer + a script in place of service but in practice systemd is much simpler and more consistent to manage.
PS: mcron is what I have been tinkering with and think will probably replace my systemd timers for most purposes.
https://www.gnu.org/software/mcron/manual/mcron.html#Introdu...
You're touching on something subtle where, like markdown, all cron look the same until they differ.
https://crontab.guru/#*_0/1_*_*_*
Oops. Point taken :)
0 * * * * this
That's exactly what I mean.
Systemd itself, including timers, is deeply coupled with the Linux API, and cannot be (easily) ported on any other system. Cron, on the other hand, exists on almost every UNIX-like system.
https://www.freedesktop.org/software/systemd/man/latest/syst...
I've never heard of a systemd timer before, but I guessed it was a type of unit file, so I just read the documentation:
https://www.freedesktop.org/software/systemd/man/latest/syst...
I have no idea from that documentation how I'd run something every hour. I guess I have to create a new unit file, and use the OnCalendar stanza? But what do I set it to? I'm directed to this page:
https://www.freedesktop.org/software/systemd/man/latest/syst...
Oh, I see I can use "hourly" but it turns out that's syntactic sugar for:
*-*-* *:00:00
0 * * * *
@hourly
I started my career as a Unix SA over 25 years ago and have worked with a lot of different Unix-flavored operating systems: SunOS/Solaris, HP/UX, FreeBSD, Linux (Slackware, RedHat, Debian), macOS/OS X, AIX. I'm familiar with all their different variations of init.
All of them are esoteric in one way or another. Some of them have their behavior right out in the open where it's easy to see (inittab and rc scripts). Others hide away massive complexity (launchd and systemd) and require extensive documentation to understand.
I appreciate all the power that systemd provides. It gets a lot of things right. But in terms of complexity, it's almost an operating system unto itself.
I'll still reply to one part:
> Oh, I see I can use "hourly" but it turns out that's syntactic sugar for:
> *-*-* *:00:00
>Is that really any easier than the cron equivalent?
> 0 * * * *
...Yes? Ask someone who's not familiar either with cron or systemd to guess what each one mean, with the context that it's supposed to be something related to dates and times. If you're vaguely familiar with how dates are usually written down, and that a star is a wildcard, you can immediately guess that the first one means "any year, any month, any day, any hour, at the first minute, first second". The cron one? It's anyone's guess.
You can argue that no other system matters (which I strongly disagree with for reasons I don't want to get into right now), but that doesn't make systemd timers any more portable.
Do you take portable to mean a program that can run on every processor arch and OS available?
The definition of the word "portable" is not the point of this comment thread (although if you want to hear my definition, see the reply to a sibling comment).
Let's take the context into account:
> hashworks:
While I support systemd timers over cron, AFAIK cron has stuff like @hourly.
> caiusdurling:
Some cron implementations do, it's not portable.
> bheadmaster:
Neither are systemd timers. I don't think there's a single system out there implementing the systemd timer interface.
However, that's a disingenious argument, because systemd timers aren't any more portable than cron implementations that use @hourly - in fact, there isn't a single system out there implementing the systemd timer interface except systemd.
In context of systemd, systemd isn't portable because it highly depends on Linux API and thus cannot be ported on any other UNIX-like (or unlike) OS.
In context of systemd timers, systemd timers aren't portable because there isn't as single alternative implementation that can interpret systemd timer unit files.
The man page lists: minutely, hourly, daily, monthly, weekly, yearly, quarterly, semiannually (and "annually" further down in examples).
It doesn't have a "hourly" directory where you can drop in scripts though, AFAIK.
systemd-analyze calendar "Mon,Tue *-*-01..04 12:00:00"