Systemd Timer Units as alternative to cronjob?

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1

Hi,

I’m having some trouble to make my cronjob run as you can see here.

Somebody suggested to use systemd timer units instead.
Is that a possibility or is it by any circumstances mandatory to run cron with one of the three given options?

Thanks for the replies!

Best regards

2

I managed to make the cronjob work, but I still would like to know if it also can be done with systemd and why there are only those three options (AJAX, Web, cron)?

Best regards

3

Hey proton,

works fine here.

First create a systemd service file: nextcloud-cron.service

[Unit]
# Execute nextcloud cron every 15 minutes.
Description=nextcloud-cron

[Service]
User=http
Nice=19
IOSchedulingClass=2
IOSchedulingPriority=7
ExecStart=/bin/bash -c php -f /srv/http/nextcloud/cron.php

Next create timer for this service: nextcloud-cron.timer

[Unit]
# Calls Nextcloud cron every 15 Minutes.
Description=nextcloud-cron

[Timer]
OnCalendar=*:0/15:00
Persistent=true
Unit=nextcloud-cron.service

[Install]
WantedBy=basic.target

Don’t forget to adjust your nextcloud User= and path in the ExecStart Statement of the service file.

Copy both files in the /etc/systemd/system directory and activate the timer. - Done.

4

Happy new year angerm! :slight_smile:

Thank you very much for this detailed explanation! :smiley:

Best regards

5

Hi,

Could you please explain the advantage of systemd over cron? Is it suggested to rather use systemd?

Thanks

6

Hello,

in which case I think you can use the service of your choice. They both do a good job here.

However, if the service is to be monitored in the sense of a daemon, systemd has advantages here:

systemd starts the service and also monitors whether it is still running. If desired, systemd can also restart the service automatically after a crash.
Dependencies at system startup are detected and, if necessary, the start of a service is written to a pipe until the calling service is ready. This speeds up the start enormously, because almost everything can be started in parallel. Everything is logged in the log.

With a little practice, service and timer units are quickly created and very flexible.

In almost all distributions, systemd is now standard. Therefore, a systemd service can be run on many installations without additional dependencies.

It is just a new and almost everywhere available method to start the system and services on Linux machines.

greetings …

2 Likes
7

Fails because bash -c only takes one argument. Only the php is run, the rest is ignored.

Demonstration (try it yourself and see):

This does not put foo in in the journal, see journalctl -b- 0
That is because bash -c echo foo only takes one argument, the foo is discarded.

$ cat whitespace.service 
[Unit]
# Execute nextcloud cron every 15 minutes.
Description=Use a systemd timer in lieu of cron.

[Service]
User=http
Nice=19
IOSchedulingClass=2
IOSchedulingPriority=7
ExecStart=/bin/bash -c 'echo foo'

This puts foo in the journal, see journalctl -b- 0.
That is because using single-quotes around ‘echo foo’ causes it to be one argument.

$ cat whitespace.service 
[Unit]
# Execute nextcloud cron every 15 minutes.
Description=Use a systemd timer in lieu of cron.

[Service]
User=http
Nice=19
IOSchedulingClass=2
IOSchedulingPriority=7
ExecStart=/bin/bash -c 'echo foo'