Xcron is an implementation of cron by Geoff Kuenning. Notable features about xcron are a careful attention to security constraints, support for a different (and somewhat easier-to-use) crontab format, and catch-up support for jobs that should have run but didn’t because the machine was off or suspended. For more details about xcron, see DOC or Geoff’s paper (tech report UCLA-CSD-990044).
Lcron is a small set of extensions to xcron that support location- and event-triggered actions. Location is primarily determined by network connectivity, events are things like current power status (A/C or battery). Applications include:
- Reminders can be sent to a user when a location is reached (``feed the cat when you get home’’).
- Location-aware queueing or tasking is easy (``print this job when I’m at work’’).
- System defaults can be updated when a location is reached (``print to the printer in room 232 when I’m at work, but to the one in my study when I’m at home’’).
- Replicated or cached data can be refreshed when convenient (``back up my hard disk when I have a good network connection’’).
Lcron is described in a paper by John Heidemann and Dhaval Shah.
For more details about xcron or lcron, please see the man pages in the distribution.
A beta release of xcron is available here. Although versions of this software have been in use for more than four years, this code may contain bugs and has limited maintenance.
Xcron should run on any variant of Unix. The lcron extensions should also be portable, but the automated installation procedure for lcron is not portable, and small OS-specific may be required to trigger cron on location changes. Lcron is regularly used on RedHat Linux and should be installable by hand on other platforms with modest effort (by someone who understands Makefiles and scripts). (See also README.lcron.)
Download xcron-20070605: source code (tar.gz),
(Download earlier snapshots: 20000417, 20000413, 19990805.)
Known bugs
20000413: no known functionality bugs.
Missing features: GNU autoconf support would be nice, parts of the lcron installation are RedHat-Linux specific. The Redhat RPMs install xcron in a funny place.