[PROPOSAL] Cron jobs
A specification proposal for LSB-compliant package cron jobs.
This is basically straight out of the Debian policy handbook, with
several suggested modifications following the proposal.
------- start of proposal --------------
Cron jobs
Packages may not touch the configuration file /etc/crontab, nor may
they modify the files in /var/spool/cron/crontabs.
If a package wants to install a job that has to be executed via cron,
it should place a file with the name if the package in one of the
following directories:
/etc/cron.daily
/etc/cron.weekly
/etc/cron.monthly
As these directory names say, the files within them are executed on a
daily, weekly, or monthly basis, respectively.
If a certain job has to be executed more frequently than `daily,' the
package should install a file /etc/cron.d/<package-name> tagged as
configuration file. This file uses the same syntax as /etc/crontab and
is processed by cron automatically. (Note, that scripts in the
/etc/cron.d directory are not handled by anacron. Thus, you should
only use this directory for jobs which may be skipped if the system is
not running.)
All files installed in any of these directories have to be scripts
(shell scripts, Perl scripts, etc.) so that they can easily be
modified by the local system administrator. In addition, they have to
be registered as configuration file.
The scripts in these directories have to check, if all necessary
programs are installed before they try to execute them. Otherwise,
problems will arise when a package was removed (but not purged), since
the configuration files are kept on the system in this situation.
------- end ----------------------------
Suggested modifications:
- replace should with shall (makes sense for all cases)
- all scripts must be XPG3 Shell compliant scripts, using a
standard location for XPG3 Shell to be determined
Open questions:
- do we require anacron in the standard base system?
- if anacron, should there be a configuration option (for any package
cron job to disable/enable anacron operation)?
- if anacron, should scripts in /etc/cron.d be handled by anacron?
- do we use the above system or an "install-cron" program wrapper?
I think this is the right way to go. The software patches for
/etc/cron.d already exist. /etc/cron.daily and friends have emerged
as de-facto Linux standards. With /etc/cron.d in play, there is more
than enough flexibility for a long time into the future.
Also, using this approach does not prevent further innovation and
non-cron-like schedulers that could replace/supplement cron in the
event someone decided to do that.
- Dan
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