NAME

ratrun.ics — iCalendar emulation for ratrun

SYNOPSIS

$ head -n1 ~/.ratrun/an-event[.ics]
BEGIN:VCALENDAR

DESCRIPTION

Internet Calendaring and Scheduling Core Object Specification (iCalendar), also commonly known by its prescribed extension .ics and much less commonly as VCALENDAR, is ubiquitously used for that purpose, and primarily distributed as text/calendar parts.

To that end, files in this format may be freely used as ratrun(8) events in ~/.ratrun/.

iCal is complicated and ratrun is not, so support is only emulated, by using

FILES

/usr/share/zoneinfo/

TZIDs are validated to exist here before being used.

SEE ALSO

rat(1), rerat.ics(7) – its X-RATSTART keys are also understood, ratrun(8)

🐀

STANDARDS

RFC5545

Unrelatedly, this emulator is expected to be compatible with most common commercial calendar front-ends and probably all sane ones; it was tested against Microsoft Outlook (2019), Microsoft Teams, aCalendar, Evolution (GNOME™), and Google Calendar™, with largely favourable results.

BUGS

Besides, of course, not actually parsing iCal, in no particular order:

• only single-event files produce favourable results; §3.6. Calendar Components, final para. states: "a complex iCalendar object that is used to capture a complete snapshot of the contents of a calendar is possible. More commonly, an iCalendar object will consist of just a single […] calendar component.", and most CUAs won't even let you export more than one at a time (the one multi-event object in the test corpus (so far!) comes from a ticket distribution system, and nothing is lost there),
• recurring of events (RRULE) isn't handled at all,
• positive and absolute VALARM TRIGGERs are ignored, all are assumed to be relative to DTSTART,
• all other VALARM fields are ignored (this is a feature actually),
• iCal has an opulent system for specifying time-zones. We consider X-WR-TIMEZONE equivalent,
• §3.2.19. Time Zone Identifier, Note kindly recommends "Implementers may want to use the naming conventions defined in existing time zone specifications such as the public-domain TZ database", and, indeed, non-Microsoft products largely do, if they don't just spec a UTC time. To support the rest, with decent hit-chance, these are tried, in order, with the first extant used:
  1. the TZID itself,
  2. the same with "Standard" removed, or
  3. 2. or 1., but only the upper-case characters (reduced to acronym);
• printf(1) %b is used to expand \ escapes.