ZIC(1M) RISC/os Reference Manual ZIC(1M)
NAME
zic - time zone compiler
SYNOPSIS
zic [ -v ] [ -d directory ] [ -l localtime ] [ filename ...
]
DESCRIPTION
zic reads text from the file(s) named on the command line
and creates the time conversion information files specified
in this input. If a filename is -, the standard input is
read.
zic can also be used to set the timezone. When your machine
is installed or updated, the timezone information found in
/etc/zoneinfo/SOURCES is automatically compiled for you. If
the file /etc/zoneinfo/localtime does not exist, the
timezone is set to US/Pacific time. To change the timezone,
look in the directory /etc/zoneinfo, determine your timezone
(you can use an abbreviation like PST, or the name of any
file found in /etc/zoneinfo), and execute the command
/etc/zic -l timezone
where ``timezone'' is the name of the timezone you need.
The timezone need only be set once.
These options are available:
-d directory
Create time conversion information files in the named
directory rather than in the standard directory named
below.
-l timezone
Use the given time zone as local time. zic will act as
if the file contained a link line of the form
Link timezone localtime
-v Complain if a year that appears in a data file is out-
side the range of years representable by time(2)
values.
Input lines are made up of fields. Fields are separated
from one another by any number of white space characters.
Leading and trailing white space on input lines is ignored.
An unquoted sharp character (#) in the input introduces a
comment which extends to the end of the line the sharp char-
acter appears on. White space characters and sharp charac-
ters may be enclosed in double quotes (") if they're to be
used as part of a field. Any line that is blank (after
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comment stripping) is ignored. Non-blank lines are expected
to be of one of three types: rule lines, zone lines, and
link lines.
Rule Lines
A rule line has the form
Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
For example:
Rule USA 1969 1973 - Apr lastSun 2:00 1:00 D
The fields that make up a rule line are:
NAME Gives the (arbitrary) name of the set of rules this
rule is part of.
FROM Gives the first year in which the rule applies. The
word minimum (or an abbreviation) means the minimum
year with a representable time value. The word max-
imum (or an abbreviation) means the maximum year
with a representable time value.
TO Gives the final year in which the rule applies. In
addition to minimum and maximum (as above), the word
only (or an abbreviation) may be used to repeat the
value of the FROM field.
TYPE Gives the type of year in which the year applies.
If TYPE is - then the rule applies in all years
between FROM and TO inclusive; if TYPE is uspres,
the rule applies in U.S. Presidential election
years; if TYPE is nonpres, the rule applies in years
other than U.S. Presidential election years. If
TYPE is something else, then zic executes the com-
mand
yearistype year type
to check the type of a year: an exit status of 0 is
taken to mean that the year is of the given type; an
exit status of 1 is taken to mean that the year is
not of the given type.
IN Names the month in which the rule takes effect.
Month names may be abbreviated.
ON Gives the day on which the rule takes effect.
Recognized forms include:
5 the fifth of the month
lastSun the last Sunday in the month
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lastMon the last Monday in the month
Sun>=8 first Sunday on or after the eighth
Sun<=25 last Sunday on or before the 25th
Names of days of the week may be abbreviated or
spelled out in full. Note that there must be no
spaces within the ON field.
AT Gives the time of day at which the rule takes
affect. Recognized forms include:
2 time in hours
2:00 time in hours and minutes
15:00 24-hour format time (for times after noon)
1:28:14 time in hours, minutes, and seconds
Any of these forms may be followed by the letter w
if the given time is local ``wall clock'' time or s
if the given time is local ``standard'' time; in the
absence of w or s, wall clock time is assumed.
SAVE Gives the amount of time to be added to local stan-
dard time when the rule is in effect. This field
has the same format as the AT field (although, of
course, the w and s suffixes are not used).
LETTER/S
Gives the ``variable part'' (for example, the ``S''
or ``D'' in ``EST'' or ``EDT'') of time zone abbre-
viations to be used when this rule is in effect. If
this field is -, the variable part is null.
Zone Lines
A zone line has the form
Zone NAME GMTOFF RULES/SAVE FORMAT [UNTIL]
For example:
Zone Australia/South-west 9:30 Aus CST 1987 Mar 15 2:00
The fields that make up a zone line are:
NAME The name of the time zone. This is the name used in
creating the time conversion information file for the
zone.
GMTOFF
The amount of time to add to GMT to get standard time
in this zone. This field has the same format as the
AT and SAVE fields of rule lines; begin the field with
a minus sign if time must be subtracted from GMT.
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RULES/SAVE
The name of the rule(s) that apply in the time zone
or, alternately, an amount of time to add to local
standard time. If this field is - then standard time
always applies in the time zone.
FORMAT
The format for time zone abbreviations in this time
zone. The pair of characters %s is used to show where
the ``variable part'' of the time zone abbreviation
goes.
UNTIL The time at which the GMT offset or the rule(s) change
for a location. It is specified as a year, a month, a
day, and a time of day. If this is specified, the
time zone information is generated from the given GMT
offset and rule change until the time specified.
The next line must be a ``continuation'' line; this
has the same form as a zone line except that the
string ``Zone'' and the name are omitted, as the con-
tinuation line will place information starting at the
time specified as the UNTIL field in the previous line
in the file used by the previous line. Continuation
lines may contain an UNTIL field, just as zone lines
do, indicating that the next line is a further con-
tinuation.
Link Lines
A link line has the form
Link LINK-FROM LINK-TO
For example:
Link US/Eastern EST5EDT
The LINK-FROM field should appear as the NAME field in some
zone line; the LINK-TO field is used as an alternate name
for that zone.
Except for continuation lines, lines may appear in any order
in the input.
WARNING & EXAMPLE
Please note that SystemV programs may display the wrong
time/date when choosing timezones outside of the U.S.
because they use a different algorithm for calculating how
far off of GMT a particular timezone lies. BSD programs use
the information in /etc/zoneinfo, which contains data files
for the different timezones around the world. The value
which the environment variable TZ takes on will determine
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which file is looked at in this directory.
The SystemV library uses *only* the name in determining how
far off of GMT a current timezone lies. Therefore, a BSD
program can correctly operate with TZ=Japan because
/etc/zoneinfo/Japan performs the appropriate mapping; but a
SystemV program needs to have TZ=JST-9. This cryptic abbre-
viation means that Japan Standard Time is 9 hours ahead of
Greenwich Mean Time. If the file /etc/zoneinfo/JST-9 con-
tains the appropriate mapping information (setup with zic,
both BSD and SystemV can operate properly when JST-9 is
placed in /etc/TZ.
Since the name "Japan" is more descriptive, we have left it
in /etc/zoneinfo as well as JST-9. Other countries should
set up similar timezone files by following the format used
in /etc/zoneinfo/SOURCES/asia for Japan.
NOTE
For areas with more than two types of local time, you may
need to use local standard time in the AT field of the ear-
liest transition time's rule to ensure that the earliest
transition time recorded in the compiled file is correct.
FILES
/etc/zoneinfo standard directory used for created
files
/etc/TZ Contains timezone where computer is
located
SEE ALSO
zdump(1M).
date(1) in the User's Reference Manual.
ctime(3) in the Programmer's Reference Manual.
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