.TH ICAL 4
.SH NAME
ical \- calendar file system
.SH SYNOPSIS
.B ical/fs
[
.B -n
] [
.B -c
.I config
] [
.B -d
.I dir
] [
.B -s
.I service
] [
.B -M
.I mtpt
] [
.B -w
.I days
] [
.B -u
.I url
] [
.B -U
.I file
] [
.B -a
.I addr
]
.SH DESCRIPTION
.I Ical/fs
presents a calendar as a file tree.
It reads iCalendar
.RB ( .ics )
files from
.I dir
(default
.BR . ),
expands recurring events, and posts a service file descriptor in
.BR /srv/\fIservice .
.PP
The default service name is
.BI ical. user . pid\fR,
as
.IR rio (1)
and
.IR plumb (1)
name theirs, so that several may run at once.
A name given with
.B -s
is used unchanged, for a singleton something else expects to find by
name.
The name posted is written to standard error.
.I Ical/fs
does not mount itself; a start script would say
.IP
.EX
ical/fs &
mount /srv/ical.$user.$apid /mnt/pim
.EE
.PP
Calendars named in
.I config
(default
.BR $home/lib/pim )
are fetched over HTTP and kept current without being asked.
Each line is a tuple of attribute-value pairs in the syntax of
.IR ndb (6):
.IP
.EX
cal=work url=https://... refresh=15m
.EE
.PP
.B Refresh
defaults to 15 minutes.
A fetch whose content is unchanged rebuilds nothing.
The
.B -u
and
.B -U
flags name a single url directly, the latter reading it from
.IR file ;
the url of a private calendar is a secret and belongs in a file
rather than in the arguments, where
.IR ps (1)
would show it.
.PP
The
.B -w
flag sets how many days either side of now recurrences are expanded
into, default 400.
.B -M
is the mount point reported in query answers, default
.BR /mnt/pim .
.B -a
also serves 9P on a TCP address.
.B -n
loads the calendars, reports what was found, and exits.
.PP
The top level contains the files
.BR ctl ,
.BR query ,
.BR alarm ,
.BR changed ,
and the directory
.BR events .
.SS Events
.B Events/date
holds one file per occurrence, at
.BI events/date/ yyyy/mm/dd/hhmm-summary\fR.
Times are local, zero filled, and four digits wide, so that a day
sorts by name.
All day events are named
.BI 0000-allday- summary\fR.
Each file holds a header of
.BI attribute :\ value
lines, a blank line, and the description:
.IP
.EX
summary: API WG
start: 2026-08-19T10:00:00-04:00
end: 2026-08-19T11:05:00-04:00
epoch: 1787148000
epochend: 1787151900
uid: 1avg0u8b0k5v4bqokqfvgr157v@google.com
event: ../../../../uuid/1avg0u8b0k5v4bqokqfvgr157v_google.com
.EE
.PP
.B Epoch
and
.B epochend
are seconds, for
.IR date (1).
.B Event
is the path of the event this occurrence belongs to; 9P has no
symbolic links.
.PP
.B Events/uuid
holds one directory per event, named for its
.BR uid ,
containing the files
.BR summary ,
.BR start ,
.BR end ,
.BR location ,
.BR description ,
.BR rrule ,
.BR organizer ,
.BR attendees ,
.BR uid ,
and
.BR raw .
Absent values have no file.
.B Attendees
holds one line per attendee: participation status, name, and address,
separated by tabs.
.B Raw
is the event as it arrived.
.SS Ctl
Reading
.B ctl
reports the source directory, the expansion window, the number of
events, and one line per calendar giving its refresh interval and the
time of its last fetch.
Writing to it accepts:
.TF "\fLwindow\fI n\fL"
.TP
.B refresh
Reload from
.IR dir .
.TP
.BI window \ n
Expand recurrences
.I n
days either side of now, and reload.
.SS Query
.B Query
answers questions the tree does not index.
Write a query, then read the answer, as with
.IR cs (8);
one path is returned per line.
A query is a list of
.IB attribute = value
terms, all of which must match:
.BR summary ,
.BR attendee ,
.BR organizer ,
.BR location ,
and
.B uid
match a substring, without regard to case;
.B from
and
.B to
bound the occurrence time and are written
.BR yyyy-mm-dd .
.IP
.EX
% echo 'attendee=michael from=2026-08-19' >/mnt/pim/query
% cat /mnt/pim/query
.EE
.PP
Holding one file descriptor across the write and the read is correct
usage.
The last answer is also returned to a descriptor that has none of its
own, so that
.B echo
and
.B cat
work.
.SS Alarm and changed
A read of
.B alarm
blocks until an alarm is due and returns the alarm time, the start of
the event, and its summary, separated by tabs.
Only
.B VALARM
triggers relative to the start are honoured.
.PP
A read of
.B changed
blocks until the tree has been rebuilt.
A program displaying a calendar should walk the tree again when it
returns rather than poll.
The whole tree is rebuilt, so open file descriptors should not be
assumed to remain valid.
.SH EXAMPLE
Serve the calendars named in the config and mount them:
.IP
.EX
% ical/fs -s pim
% mount /srv/pim /mnt/pim
% pim/agenda
.EE
.SH SOURCE
.B /sys/src/pim
.SH "SEE ALSO"
.IR agenda (1),
.IR date (1),
.IR ndb (6),
.IR cs (8)
.PP
Desruisseaux,
``Internet Calendaring and Scheduling Core Object Specification'',
RFC 5545.
.SH BUGS
Embedded
.B VTIMEZONE
definitions are ignored;
.B TZID
is resolved by IANA name.
.PP
.B RECURRENCE-ID
overrides are applied, but
.B METHOD:CANCEL
is not.
.PP
Absolute alarm triggers,
.BR RELATED=END ,
and repeating alarms are ignored.
.PP
Nothing can be written but
.B ctl
and
.BR query .
Replying to an invitation is not yet possible.