# GNU Mcron
This is GNU Mcron, a tool to run jobs at scheduled times. It is a complete
replacement for Vixie cron. Besides supporting the traditional Vixie syntax
for its configuration files, GNU Mcron offers the possibility to define jobs
using the Scheme language.
See the INSTALL file for generic information about how to configure and
install GNU Mcron. If this file is not present, see HACKING for preliminary
build instructions.
# IMPORTANT NOTICES
Do not (yet) install this software on a machine which relies for its
functioning on its current set of crontabs.
To not replace the cron daemon on a system, the package must be installed with
the `--disable-multi-user` configure option.
Before installing this package for the first time, it is necessary to
terminate any running cron daemons on your system. If your old cron is not
Vixie or accurately Vixie compatible (files in /var/cron/tabs*,
/var/cron/allow, /var/cron/deny, /etc/crontab, /var/run/cron.pid) then you
will need to clear out all old crontabs and make new ones afresh - or else
look very carefully at the options you pass to the package configure script,
as follows.
It is often the case that GNU/Linux distributions and other Unices hacked the
cron daemon to use different directories to those above. You can use configure
options `--spool-dir`, `--socket-file`, `--allow-file`, `--deny-file`,
`--pid-file` and `--tmp-dir` to make mcron behave similarly. Note that, with
the exception of tmp-dir, none of these files or directories should be
accessible by ordinary (non-root) users.
If your old cron is Vixie, or very similar, mcron should fall right into place
where your old cron was (the binaries cron and crontab will be replaced, but
if your existing system has a binary called crond, you should make this a link
to mcron), and you should be able to continue to use your existing crontabs
without noticing any changes.
If you don't want to clobber your existing cron executables, you can specify
the `--program-prefix` option to configure with a prefix ending in a
non-alphabetic character, for example "m.", and then run the programs as
`m.mcron`, `m.cron` (or `m.crond`) and `m.crontab`.
After installation, read the info file for full instructions for use (typing
'`info mcron`' at the command line should suffice). Notes for end users,
sysadmins, and developers who wish to incorporate mcron into their own
programs are included here.
Features which might be implemented sometime sooner or later are noted in the
TODO file.
Please send all bug reports to [bug-mcron@gnu.org](mailto:bug-mcron@gnu.org).
Mcron is free software. See the file COPYING for copying conditions.
The mcron development home page is at
[https://rdmp.org/dmbcs/mcron](https://rdmp.org/dmbcs/mcron) and the latest
version can be obtained from
[https://rdmp.org/dmbcs/mcron.git](https://rdmp.org/cgit/mcron.git).
The GNU home page for the project is
[http://www.gnu.org/software/mcron](http://www.gnu.org/software/mcron).
---
Copyright © 2003, 2005, 2006, 2012, 2014, 2024 Dale Mellor<br>
Copyright © 2018 Mathieu Lirzin
Copying and distribution of this file, with or without modification, are
permitted in any medium without royalty provided the copyright notice and this
notice are preserved. This file is offered as-is, without warranty of any
kind.
