mcron (Mellor’s cron) is a 100% compatible replacement for Vixie cron.
It is written in pure Guile, and allows configuration files to be written in scheme (as well as the POSIX crontab format) for infinite flexibility in specifying when jobs should be run.
This is free and open source software.
Key Features
- Does not consume CPU resources when not needed. Many cron daemons only run jobs once an hour, or even just once a day.
- Can easily allow for finer time-points to be specified, i.e. seconds. In principle this could be extended to microseconds, but this is not implemented.
- Times can be more or less regular. For example, a job that runs every 17 hours can be specified, or a job that runs on the first Sunday of every month.
- Times can be dynamic. Arbitrary Guile (scheme) code can be provided to compute the next time that a command needs to be run. This could, for example, take the system load into consideration.
- Turns out to be easy to provide 99.9% backwards compatibility with Vixie cron.
- Each user looks after his own files in his own directory. He can use more than one to break up complicated cron specifications.
- Each user can run his own daemon. This removes the need for suid programs to manipulate the crontabs, and eliminates many security concerns that surround all existing cron programs.
- The user can obtain an advance schedule of all the jobs that are due to run.
- Vixie cron is implemented in 4500 lines of C code; mcron is 1500 lines of scheme, despite the fact that it offers many more features and much more flexibility, and complete compatibility with Vixie cron.
Website: www.gnu.org/software/mcron
Support:
Developer: Dale Mellor
License: GNU General Public License v3.0

mcron is written in Scheme. Learn Scheme with our recommended free books and free tutorials.
Related Software
| Alternatives to cron | |
|---|---|
| cronie | Modern day version of cron and associated tools |
| fcron | Designed for systems which are not continuously running or regularly |
| systemd | Suite of basic building blocks for a Linux system |
| mcron | 100% compatible replacement for Vixie cron |
| anacron | Designed for systems which are not continuously running |
| Jobber | Run commands to a schedule |
| bcron | Designed with secure operations in mind |
| Cronicle | Multi-server task scheduler and runner |
| Supercronic | Crontab-compatible job runner designed for container environments |
| runcron | Minimal cron alternative for automated and container-friendly environments |
Read our verdict in the software roundup.
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