[FAQ] What are the differences between the cron daemons?

[vandalman]

There was a request for a cron FAQ comparing the cron daemons. I compiled this from the Gentoo Linux Cron Guide, this is not my original work (I cite my source in the FAQ). I wanted to get people talking about this question.

-- Begin FAQ --
Question: What are the differences between the cron daemons?

Vixie Cron sys-process/vixie-cron - Vixie cron is a full featured cron implementation based on SysV cron. Each user has his own crontab and is allowed to specify environment variables within that crontab. Unlike the other cron variants, it also offers support for SELinux and PAM. It supports fewer architectures than Dcron, but more than Fcron.

Dillon's Cron sys-process/dcron - Dcron aims to be a simple, elegant and secure implementation of cron. It does not allow the specification of environment variables in crontabs and all cron-jobs are run from /bin/sh. Like Vixie cron, each user has his own crontab.

Fcron sys-process/fcron - Fcron aims at replacing Vixie cron and Anacron. It is designed to work on systems that are not continuously running and it is packed with extra features. It has job startup constraints, job serialization controls, the ability to assign nice values to jobs and the ability to schedule jobs to run at system startup.

Taken from Gentoo Linux Cron Guide
-- End FAQ --

Should Anacron be part of this FAQ?

Anacron sys-process/anacron - Anacron is not a cron daemon, it is something that usually works in conjunction with one. It executes commands at intervals specified in days and it does not assume that the system is running continuously; it will run jobs that were missed while the system was down. Anacron usually relies on a cron daemon to run it each day.

[jsosic]

Nobody commented on this yet, so I'll do it

FAQ is great, but I think it's a little incomplete... It would be great if users of alternate cron implementations (especially fcron) could write sample configurations, and benefits of using different cron. For example, I would like to use fcron, so I could replace anacron/vixie combination at my desktops....
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[mope]

I'm interested in using fcron, too.