Dates

In CVS, all dates and times are processed by a version of the GNU getdate function, which can translate dates and times given in several different formats. Case is always irrelevant when interpreting dates. Spaces are permitted in date strings, but in the command-line client, a string with spaces should be surrounded by quotes. If a year is 0 to 99, it is considered to be in the twentieth century.

If a time is not given, midnight at the start of the date is assumed. If a time zone is not specified, the date is interpreted as being in the client's local time zone.

Legal Date Formats

The legal time and date formats for CVS are defined by the ISO 8601 standard and RFC 822 as amended by RFC 1123. Other formats can be interpreted, but CVS is designed to handle only these standards.

ISO 8601

The basic ISO 8601 date format is as follows:

  year-month-day hours:minutes:seconds

All values are numbers with leading zeros to ensure that the correct number of digits are used. Hours are given in 24-hour time. This produces the structure YYYY-MM-DD HH:MM:SS, which is internationally acceptable and can be sorted easily. You can use a date, a time, or both.

If you're using ISO 8601 format with the hyphens, the full date is required in CVS. The YYYYMMDD date format is also acceptable and can be abbreviated to YYYYMM or YYYY.

The HH and HH:MM time formats are acceptable. Times can also be specified without the colon, so HHMMSS or HHMM are usable.

Be aware that HHMM may be misinterpreted as YYYY. Get into the habit of using separators.

In strict ISO 8601 format, a T is required between the date and the time, but CVS understands this format with or without the T. The ISO 8601 standard also states that a Z at the end of the string designates UTC (Universal Coordinated Time), but CVS does not recognize the use of Z.

RFC 822 and RFC 1123

RFCs 822 and 1123 define a precise time format:

    [DDD ,] DD MMM YYYY HH:MM[:SS] ZZZ

These are the terms in the format:

DDD

A three-letter day of the week.

DD

A two-digit date of the month.

MMM

A three-letter month.

YYYY

The year (it must be a four-digit year).

HH

Hours.

MM

Minutes.

SS

Seconds.

ZZZ

The time zone (can be the text abbreviation, a military time zone, or an offset from UTC in hours and minutes).

Legal Date Keywords

CVS also allows short English phrases such as "last Wednesday" and "a month ago" to be used in place of actual dates. Case is not significant, and CVS can understand plurals. These are the keywords it understands:

Month names

January, February, March, April, May, June, July, August, September, October, November, and December.

Month abbreviations

Jan, Feb, Mar, Apr, Jun, Jul, Aug, Sep, Sept, Oct, Nov, and Dec.

Days of the week

Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, and Saturday.

Day abbreviations

Sun, Mon, Tue, Tues, Wed, Wednes, Thu, Thur, Thurs, Fri, and Sat.

Units of time

year, month, fortnight, week, day, hour, minute, min, second, and sec.

Relative times

tomorrow, yesterday, today, and now.

Meridian qualifiers

am, pm, a.m., and p.m.

Modifiers

a, last, this, next, and ago.

Sequences

first, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, and twelfth. (second can't be used as a sequence term, because it is used as a time unit.)

Time Zones

CVS understands time zones expressed in offsets from UTC, such as +0700 (7 hours ahead) and -1130 (11 hours, 30 minutes behind). The format for these time zones is +HHMM or -HHMM, where + means ahead of UTC and - means behind UTC. CVS also understands time-zone abbreviations and ignores case and punctuation when interpreting them.

NOTE

Some of the time-zone abbreviations CVS recognizes are ambiguous. CVS recognizes only one meaning for each of the ambiguous time zones. However, the meaning that is recognized may vary depending on your operating system, and on how CVS was configured when it was compiled.

Table 13-2 shows the valid civilian time-zone abbreviations for CVS. Table 13-3 shows military time-zone abbreviations that CVS recognizes.

Table 13-2. Civilian time-zone abbreviations

Abbrev.	Offset / Name	Abbrev.	Offset / Name
gmt	+0000 Greenwich Mean	met	-0100 Middle European
ut	+0000 Coordinated Universal Time	mewt	-0100 Middle European Winter
utc	+0000 Coordinated Universal Time	mest	Middle European Summer
wet	+0000 Western European	swt	-0100 Swedish Winter
bst	+0000 British Summer (ambiguous with Brazil Standard)	sst	Swedish Summer (ambiguous with South Sumatra)
wat	+0100 West Africa	fwt	-0100 French Winter
at	+0200 Azores	fst	French Summer
bst	+0300 Brazil Standard (ambiguous with British Summer)	eet	-0200 Eastern Europe, USSR Zone 1
gst	+0300 Greenland Standard (ambiguous with Guam Standard)	bt	-0300 Baghdad, USSR Zone 2
nft	+0330 Newfoundland	it	-0330 Iran
nst	+0330 Newfoundland Standard (ambiguous with North Sumatra)	zp4	-0400 USSR Zone 3
ndt	Newfoundland Daylight	zp5	-0500 USSR Zone 4
ast	+0400 Atlantic Standard	ist	-0530 Indian Standard
adt	Atlantic Daylight	zp6	-0600 USSR Zone 5
est	+0500 Eastern Standard	nst	-0630 North Sumatra (ambiguous with Newfoundland Summer)
edt	Eastern Daylight	sst	-0700 South Sumatra, USSR Zone 6 (ambiguous with Swedish Summer)
cst	+0600 Central Standard	wast	-0700 West Australian Standard
cdt	Central Daylight	wadt	West Australian Daylight
mst	+0700 Mountain Standard	jt	-0730 Java
mdt	Mountain Daylight	cct	-0800 China Coast, USSR Zone 7
pst	+0800 Pacific Standard	jst	-0900 Japan Standard, USSR Zone 8
pdt	Pacific Daylight	cast	-0930 Central Australian Standard
yst	+0900 Yukon Standard	cadt	Central Australian Daylight
ydt	Yukon Daylight	east	-1000 Eastern Australian Standard
hst	+1000 Hawaii Standard	eadt	Eastern Australian Daylight
hdt	Hawaii Daylight	gst	-1000 Guam Standard, USSR Zone 9 (ambiguous with Greenland Standard)
cat	+1000 Central Alaska	nzt	-1200 New Zealand
ahst	+1000 Alaska-Hawaii Standard	nzst	-1200 New Zealand Standard
nt	+1100 Nome	nzdt	New Zealand Daylight
idlw	+1200 International Date Line West	idle	-1200 International Date Line East
cet	-0100 Central European

Table 13-3. Military time-zone abbreviations

Name	Offset	Name	Offset	Name	Offset	Name	Offset	Name	Offset
a	+0100	f	+0600	l	+1100	q	-0400	v	-0900
b	+0200	g	+0700	m	+1200	r	-0500	w	-1000
c	+0300	h	+0800	n	-0100	s	-0600	x	-1100
d	+0400	i	+0900	o	-0200	t	-0700	y	-1200
e	+0500	k	+1000	p	-0300	u	-0800	z	+0000