--version
Output version information and exit.
--help Output short usage message and exit.
-b bloat
Output backward-compatibility data as specified by bloat.
If bloat is fat, generate additional data entries that
work around potential bugs or incompatibilities in older
software, such as software that mishandles the 64-bit
generated data. If bloat is slim, keep the output files
small; this can help check for the bugs and
incompatibilities. Although the default is currently fat,
this is intended to change in future zic versions, as
software that mishandles the 64-bit data typically
mishandles timestamps after the year 2038 anyway. Also
see the -r option for another way to shrink output size.
-d directory
Create time conversion information files in the named
directory rather than in the standard directory named
below.
-l timezone
Use timezone as local time. zic will act as if the input
contained a link line of the form
Link timezone localtime
-L leapsecondfilename
Read leap second information from the file with the given
name. If this option is not used, no leap second
information appears in output files.
-p timezone
Use timezone's rules when handling nonstandard TZ strings
like "EET-2EEST" that lack transition rules. zic will act
as if the input contained a link line of the form
Link timezone posixrules
This feature is obsolete and poorly supported. Among
other things it should not be used for timestamps after
the year 2037, and it should not be combined with -b slim
if timezone's transitions are at standard time or
Universal Time (UT) instead of local time.
-r [@lo][/@hi]
Reduce the size of output files by limiting their
applicability to timestamps in the range from lo
(inclusive) to hi (exclusive), where lo and hi are
possibly-signed decimal counts of seconds since the Epoch
(1970-01-01 00:00:00 UTC). Omitted counts default to
extreme values. For example, 'zic -r @0' omits data
intended for negative timestamps (i.e., before the Epoch),
and 'zic -r @0/@2147483648' outputs data intended only for
nonnegative timestamps that fit into 31-bit signed
integers. On platforms with GNU date, 'zic -r @$(date
+%s)' omits data intended for past timestamps. Also see
the -b slim option for another way to shrink output size.
-t file
When creating local time information, put the
configuration link in the named file rather than in the
standard location.
-v Be more verbose, and complain about the following
situations:
The input specifies a link to a link.
A year that appears in a data file is outside the range of
representable years.
A time of 24:00 or more appears in the input. Pre-1998
versions of zic prohibit 24:00, and pre-2007 versions
prohibit times greater than 24:00.
A rule goes past the start or end of the month. Pre-2004
versions of zic prohibit this.
A time zone abbreviation uses a %z format. Pre-2015
versions of zic do not support this.
A timestamp contains fractional seconds. Pre-2018
versions of zic do not support this.
The input contains abbreviations that are mishandled by
pre-2018 versions of zic due to a longstanding coding bug.
These abbreviations include 'L' for 'Link', 'mi' for
'min', 'Sa' for 'Sat', and 'Su' for 'Sun'.
The output file does not contain all the information about
the long-term future of a timezone, because the future
cannot be summarized as an extended POSIX TZ string. For
example, as of 2019 this problem occurs for Iran's
daylight-saving rules for the predicted future, as these
rules are based on the Iranian calendar, which cannot be
represented.
The output contains data that may not be handled properly
by client code designed for older zic output formats.
These compatibility issues affect only timestamps before
1970 or after the start of 2038.
The output file contains more than 1200 transitions, which
may be mishandled by some clients. The current reference
client supports at most 2000 transitions; pre-2014
versions of the reference client support at most 1200
transitions.
A time zone abbreviation has fewer than 3 or more than 6
characters. POSIX requires at least 3, and requires
implementations to support at least 6.
An output file name contains a byte that is not an ASCII
letter, '-', '/', or '_'; or it contains a file name
component that contains more than 14 bytes or that starts
with '-'.
