- tz - lists.iana.org

mktime() failures under PCTS testing [forwarded with permission]
by ado March 23, 1994

March 23, 1994

> From grant(a)osf.org Tue Mar 22 17:47:33 1994 > Return-Path: <grant(a)osf.org> > Received: from postman.osf.org by elsie.nci.nih.gov (4.1/SMI-4.1) > id AA07444; Tue, 22 Mar 94 17:47:32 EST > Received: from vishnu.osf.org by postman.osf.org (5.64+/OSF 1.0) > id AA27681; Tue, 22 Mar 94 17:47:26 -0500 > Message-Id: <9403222247.AA27681(a)postman.osf.org> > To: ado(a)elsie.nci.nih.gov (Arthur David Olson) > Cc: grant(a)osf.org > Subject: mktime() failures under PCTS testing > Date: Tue, 22 Mar 1994 17:47:21 -0500 > From: Grant Sullivan <grant(a)osf.org> > Status: RO > > > Hi Arthur, > > I am a contractor at the Open Software Foundation, Cambridge, MA, responsible > for helping to make sure that OSF/1 R1.3 utlities and libraries are > conforming to POSIX.1, POSIX.2, XPG4, and other standards. > > My department's QA group recently completed a PCTS test of our current OSF/1 > libc, and reported to me that there were a number of mktime() failures in > PCTS STD/LS/mktime, such as the following: > > 5.<p1>.5.1.1. Preparation [4009] > Setup environment for testing. > > 5.<p1>.5.1.2. Testing [4009] > TZ is of the form: TZ=dst0std,J057,J059 > Non-leap year, one second prior to Jstart_day time. > > MESSAGE (5.<p1>.5.1.2.): > Testing local time of: Tue Feb 26 01:59:59 1991 > PCTS action taken: CONTINUE > > 5.<p1>.5.1.3. Testing [4009] > Non-leap year, at ambiguous Jstart_day time. > > MESSAGE (5.<p1>.5.1.3.): > Testing local time of: Tue Feb 26 02:00:00 1991 > PCTS action taken: CONTINUE > > ERROR (5.<p1>.5.1.3.): > Call to mktime() failed (returned -1). > PCTS action taken: CONTINUE > > ERROR (5.<p1>.5.1.3.): > Incorrect time returned by call to mktime(). > Expected: 667530000 Or: 667533600 > Actual: -1 > PCTS action taken: CONTINUE > > This particular test calls mktime() with tm_isdst set to -1, so it is expecting > mktime() to return either the standard time value (667530000), or the > daylight time value (667533600), under the apparent assumption that if > tm_isdst == -1, then mktime() would attempt to determine if tm_isdst should be > 0 or 1 and return the proper seconds, and adjust the struct tm accordingly. > > Our current OSF/1 libc ctime.c is based on BSD 4.4-alpha snapshot > "@(#)ctime.c 5.26 (Berkeley) 2/23/91" > with additional fixes from your June'93 kit: > elsieid[] = "@(#)localtime.c 7.9" > plus some other adjustments. > > There are quite a few PCTS failures, but I think they all boil down to a common > cause: mktime() returns -1 when tm_isdst = -1 and the tm structure specifies > the daylight savings time day, and a time at or within the first hour of > daylight savings time. > > I have created a simple test program, based on the XPG4 mktime() example, > which exercises the first PCTS failure case above. I've tried this on > several systems which have older versions of the Zoneinfo package, and on > several systems which don't have the package. I got the same failure on the > older Zoneinfo systems I tested, and mktime() returned 667530000, and set > tm_isdst to 0 on the several systems I tested which don't use the package. > > My own interpretation of the XPG4 and POSIX.2 standards suggest that mktime() > should return 667533600, and reset the passed tm_isdst to 1, under the belief > that for the above case, daylight savings starts exactly at > Tue Feb 26 02:00:00 1991 > for TZ=dst0std,J057,J059, instead of after this time, i.e. instead of at > Tue Feb 26 02:00:01 1991 > > A friend of mine at another company told me he had run into similar mktime() > problems with the FIPS151-2 test suite. He made alterations which resulted > in mktime() returning 667533600, and tm_isdst reset to 1, so we both have the > same interpretations of the XPG4 and POSIX.1 standards. His version of > mktime() was based on something older than your June'93 kit. > > I am wondering what mktime() in your current kit does in this case? Do you > think it should return: > > -1 , tm_isdst = -1 > or 667530000, tm_isdst = 0 > or 667533600, tm_isdst = 1 > > ? > > I am attaching a test program. > > Thanks very much for your help, > > Grant W. Sullivan, grant(a)osf.org > Open Software Foundation > 11 Cambridge Center, > Cambridge, MA 02142 > > > mktime_XPG4_example.c > ========================================================================== > /* XPG4, pg. 276 mktime() example > * > * with input data from PCTS STD/LS/mktime 8.1.58_09 5.1.3 test > * > */ > > #include <stdio.h> > #include <time.h> > > #include <stdlib.h> > > struct tm time_str; > > char daybuf[20]; > > /* values for struct tm; from PCTS STD/LS/mktime 8.1.58_09.c */ > #define TZ_value "std0dst,J057,J059" > #define TM_year 1991 /* non-leap year */ > #define TM_mon 2 /* dst start month -- February */ > #define TM_mday 26 /* dst start day J057 non-leap year */ > #define TM_hour 2 /* for J057 dst start hour */ > #define TM_min 0 /* for J057 dst start hour/min */ > #define TM_sec 0 /* for J057 dst start hour/min/sec */ > #define TM_wday -1 /* don't know */ > #define TM_yday -1 /* don't know */ > #define TM_isdst -1 /* don't know if std or dst */ > #define MKTIME_expected 667530000L > > > main() > { > time_t mktime_returned; > > printf("mktime test: PCTS/STD/LS/mktime 8.1.58_9 Assert 5.1.3\n"); > printf("mktime test: for this test, set TZ=dst0std,J057,J059\n"); > printf("current value of TZ = %s\n", getenv("TZ")); > > if (setenv("TZ", TZ_value, 1) != 0) { > printf("resetting TZ failed\n"); > exit(1); > } > printf("new value of TZ = %s\n", getenv("TZ")); > > time_str.tm_year = TM_year - 1900; > time_str.tm_mon = TM_mon - 1; > time_str.tm_mday = TM_mday; > time_str.tm_hour = TM_hour; > time_str.tm_min = TM_min; > time_str.tm_sec = TM_sec; > time_str.tm_wday = TM_wday; > time_str.tm_yday = TM_yday; > time_str.tm_isdst = TM_isdst; > > printf("time_str tm struct set to:\n year = %d, mon = %d, mday = %d, hour = %d, min = %d, sec = %d, wday = %d, yday = %d, isdst = %d\n", > time_str.tm_year, time_str.tm_mon, time_str.tm_mday, time_str.tm_hour, time_str.tm_min, time_str.tm_sec, time_str.tm_wday, time_str.tm_yday, time_str.tm_isdst); > printf("expected value from mktime = %d\n", MKTIME_expected); > > if ((mktime_returned = mktime(&time_str)) == (time_t)-1) { > (void)puts("mktime returned -1 (-unknown-)"); > printf("mktime() final time_str tm struct reset to:\n year = %d, mon = %d, mday = %d, hour = %d, min = %d, sec = %d, wday = %d, yday = %d, isdst = %d\n", > time_str.tm_year, time_str.tm_mon, time_str.tm_mday, time_str.tm_hour, time_str.tm_min, time_str.tm_sec, time_str.tm_wday, time_str.tm_yday, time_str.tm_isdst); > exit(1); > } > else { > printf("mktime returned value = %d\n", (int) mktime_returned); > printf("mktime() final time_str tm struct reset to:\n year = %d, mon = %d, mday = %d, hour = %d, min = %d, sec = %d, wday = %d, yday = %d, isdst = %d\n", > time_str.tm_year, time_str.tm_mon, time_str.tm_mday, time_str.tm_hour, time_str.tm_min, time_str.tm_sec, time_str.tm_wday, time_str.tm_yday, time_str.tm_isdst); > > (void)strftime(daybuf, sizeof(daybuf), "%A", &time_str); > (void)puts(daybuf); > } > > exit(0); > } > ==========================================================================

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Re: Does anyone have the source for this function?
by myersn＠roguewave.com March 22, 1994

March 22, 1994

> Does anyone have a UNIX function for converting a time from timezoneX > to timezoneY? I know how to write this by mucking with char** environ > and by calling tzset(), but I'm interested in a more elegant solution > (perhaps using fields in the tm structure). > > convert(timezoneX, timezoneY, inputTime, outputTime) > > The char** environ solution seems to me to be inelegant because > > 1) I have to reread a file whenever I call tzset() (I think), > and > > 2) while I'm doing the conversion the call to tzset() has a > global effect on my process. If I'm interrupted by a > signal handler that displays the time it will be in a > foreign timezone. My current best solution is to use the Rogue Wave Tools.h++ library class RWZone. Nathan Myers myersn(a)roguewave.com

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Does anyone have the source for this function?
by aaron＠lehman.com March 22, 1994

March 22, 1994

Does anyone have a UNIX function for converting a time from timezoneX to timezoneY? I know how to write this by mucking with char** environ and by calling tzset(), but I'm interested in a more elegant solution (perhaps using fields in the tm structure). convert(timezoneX, timezoneY, inputTime, outputTime) The char** environ solution seems to me to be inelegant because 1) I have to reread a file whenever I call tzset() (I think), and 2) while I'm doing the conversion the call to tzset() has a global effect on my process. If I'm interrupted by a signal handler that displays the time it will be in a foreign timezone. aaron(a)lehman.com

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Time Conversoin Question [forwarded with permission]
by ado March 21, 1994

March 21, 1994

> From aaron(a)lehman.com Thu Mar 17 16:49:11 1994 > Return-Path: <aaron(a)lehman.com> > Received: from lehman.com by elsie.nci.nih.gov (4.1/SMI-4.1) > id AA28619; Thu, 17 Mar 94 16:49:08 EST > Received: from relay.lehman.com by lehman.com (8.6.4/LB 0.1) > id QAA19119; Thu, 17 Mar 1994 16:48:58 -0500 > Received: from killer.lehman.com by relay.lehman.com (4.1/LB-0.6) > id AA04769; Thu, 17 Mar 94 16:48:51 EST > Received: from yen.lehman.com by killer.lehman.com (5.0/SMI-SVR4) > id AA29096; Thu, 17 Mar 1994 16:48:48 +0500 > Date: Thu, 17 Mar 1994 16:48:48 +0500 > From: aaron(a)lehman.com (Aaron Akman) > Message-Id: <9403172148.AA29096(a)killer.lehman.com> > Received: by yen.lehman.com (4.1/SMI-4.1) > id AA03187; Thu, 17 Mar 94 16:48:45 EST > To: ado(a)elsie.nci.nih.gov > Subject: Time Conversion Question > Content-Length: 1037 > Status: RO > > Arthur, > > I've downloaded your timezone stuff (got pointers from Arnold Robbins > and Don Libes), and have a question: > > I'm looking to convert from GMT to one of a few timezones, or from one > timezone to another. I'm concerned about setting TZ and calling > tzset() because I think it changes some global state associated with > the process. If I were interrupted before setting TZ back and > re-calling tzset(), I could have an interrupt function that doesn't > have the right local TZ setting. I.e. > > get_other_local_time(char* tzsetting) > { > oldsetting = temporarily_set_TZ(tzsetting); > tzset(); > > do_time_stuff_with_alternate_TZ(); > > /* i could get interrupted here by a signal handler > that needs the real local time!! */ > > set_TZ_back(oldsetting); > tzset(); > } > > Is there a better way? Is it true the effect of tzset() global? I > haven't gone through the .c files in depth yet. > > It seems like this should be a common problem for a globally > distributed system. > > Thanks in advance for any advice, > Aaron Akman > aaron(a)lehman.com > 212 464 3978

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%V [forwarded]
by ado Feb. 28, 1994

Feb. 28, 1994

> From arnold(a)skeeve.atl.ga.us Sat Feb 26 21:12:21 1994 > Received: from emory.mathcs.emory.edu by elsie.nci.nih.gov (4.1/SMI-4.1) > id AA18459; Sat, 26 Feb 94 21:12:18 EST > Received: from skeeve.UUCP by > emory.mathcs.emory.edu (5.65/Emory_mathcs.3.4.19) via UUCP > id AA09626 ; Sat, 26 Feb 94 21:12:14 -0500 > Return-Path: arnold(a)skeeve.atl.ga.us > Received: by skeeve.atl.ga.us (/\==/\ Smail3.1.22.1 #22.1) > id <m0paal5-00013rC(a)skeeve.atl.ga.us>; Sat, 26 Feb 94 20:57 EST > Message-Id: <m0paal5-00013rC(a)skeeve.atl.ga.us> > From: arnold(a)skeeve.atl.ga.us > Date: Sat, 26 Feb 1994 20:57:26 -0500 > X-Ultrix: Just Say NO! > X-Important-Saying: Premature Optimization Is The Root Of All Evil. > X-Mailer: Mail User's Shell (7.2.5 10/14/92) > To: ado(a)elsie.nci.nih.gov > Subject: any comment on this? > Status: RO > > --- Forwarded mail from Tor Lillqvist <emory!tik.vtt.fi!tml> > > >From emory!tik.vtt.fi!tml Wed Feb 23 08:12:20 1994 > Return-Path: <emory!tik.vtt.fi!tml> > Received: by skeeve.atl.ga.us (/\==/\ Smail3.1.22.1 #22.1) > id <m0pZJNz-00013zC(a)skeeve.atl.ga.us>; Wed, 23 Feb 94 08:12 EST > Received: from tiuhti.tik.vtt.fi by > emory.mathcs.emory.edu (5.65/Emory_mathcs.3.4.19) via SMTP > id AA26972 ; Wed, 23 Feb 94 08:07:40 -0500 > Received: from localhost (tml@localhost) by tiuhti.tik.vtt.fi (8.6.5/8.6.5) id PAA28498; Wed, 23 Feb 1994 15:07:33 +0200 > Date: Wed, 23 Feb 1994 15:07:33 +0200 > From: Tor Lillqvist <emory!tik.vtt.fi!tml> > Message-Id: <199402231307.PAA28498(a)tiuhti.tik.vtt.fi> > To: arnold(a)skeeve.atl.ga.us (Arnold Robbins) > In-Reply-To: arnold(a)skeeve.atl.ga.us's message of 22 Feb 1994 17:21:29 -0800 > Subject: v27i207: strftime-6.0 - yet another strftime(3) and date(1), Part01/01 > Mime-Version: 1.0 > Content-Type: text/plain; charset=us-ascii > Content-Transfer-Encoding: 7bit > > >>>>> On 22 Feb 1994 17:21:29 -0800, arnold(a)skeeve.atl.ga.us (Arnold Robbins) said: > > (to wit: if the week containing January 1 has four or more > > days in the new year, then it is week 1, otherwise it is > > week 53 of the previous year and the next week is week 1). > > Nope, it can also be week 52 of the previous year. For instance this > year's (1994) January 1st an 2nd were in week 52 of 1993. "The highest > numbered week of the previous year (52 or 53)" would be more correct. > > I guess you really need a format character for "what year does the > week number output by %V refer to", also. Otherwise it's hard to find > any good use for the %V format in a program or script. If, for > instance, you use `date +%V` to form the name of a weekly log file > accumulated daily, then the logging from January 1 and 2 in 1994 > should go to the log file for week 52 of 1993, not to the log file for > week 52 of 1994... > > > --- End of forwarded message from Tor Lillqvist <emory!tik.vtt.fi!tml>

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tzcode94d.tar.gz and tzdata94d.tar.gz
by ado Feb. 24, 1994

Feb. 24, 1994

The files tzcode94d.tar.gz and tzdata94d.tar.gz are now available for anonymous ftp from the ~ftp/pub directory on elsie.nci.nih.gov (128.231.16.1). These files incorporate the changes to avoid clashes with POSIX semantics for zones such as GMT+4; some other very minor housekeeping is also present. --ado

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v27i207: strftime-6.0 - yet another strftime(3) and date(1), Part01/01
by Monty Solomon Feb. 23, 1994

Feb. 23, 1994

Begin forwarded message: Path: decwrl!vixie!vixie!not-for-mail From: arnold(a)skeeve.atl.ga.us (Arnold Robbins) Newsgroups: comp.sources.unix Subject: v27i207: strftime-6.0 - yet another strftime(3) and date(1), Part01/01 Date: 22 Feb 1994 17:21:29 -0800 Organization: Vixie Enterprises Lines: 1245 Sender: vixie(a)vix.com Approved: vixie(a)gw.home.vix.com Nntp-Posting-Host: gw.home.vix.com To: unix-sources(a)pa.dec.com Submitted-By: arnold(a)skeeve.atl.ga.us (Arnold Robbins) Posting-Number: Volume 27, Issue 207 Archive-Name: strftime-6.0/part01 [ this recurring package is the cleanest, nicest date(1) and strftime(3) i have ever seen, including all free or vendor systems. --vix ] It seems to be an annual event, something in the circling of the stars overhead, that requires me to post this, at least once a year. (:-) This version fixes bugs in the calculations for %U, %W, and %V and output formats of several of the others (they now have leading zeros if necessary). It also fixes a small bug in date.c. Although this is only the fourth version posted c.s.u, it is the sixth one to go to the net, the first two were in comp.sources.misc. So I don't know if this is strftime 4.0 or 6.0, you can decide. I sincerely hope this will be it (at least 'til next year! :-) Arnold Robbins -- The Basement Computer | Laundry increases Internet: arnold(a)skeeve.ATL.GA.US | exponentially in the UUCP: emory!skeeve!arnold | number of children. Bitnet: Forget it. Get on a real network. | -- Miriam Robbins #! /bin/sh echo - 'README' cat << 'EOF' > 'README' Tue Feb 15 08:26:04 EST 1994 This package implements the Posix 1003.2 date command, as a wrapper around an extended version of the ANSI strftime(3) library routine. Everything in it is public domain. Arnold Robbins -- The Basement Computer | Laundry increases Internet: arnold(a)skeeve.ATL.GA.US | exponentially in the UUCP: { gatech, emory }!skeeve!arnold | number of children. Bitnet: Forget it. Get on a real network. | -- Miriam Robbins EOF echo - 'Makefile' cat << 'EOF' > 'Makefile' # Makefile for PD date and strftime SRCS= date.c strftime.c OBJS= date.o strftime.o DOCS= date.1 strftime.3 # Uncomment the define of HAVE_TZNAME if your system has the tzname[] array. # Uncomment the define of TM_IN_SYS_TIME if struct tm is in <sys/time.h> CFLAGS= -O #-DHAVE_TZNAME #-DTM_IN_SYS_TIME date: $(OBJS) $(CC) $(CFLAGS) $(OBJS) -o $@ date.o: date.c strftime.o: strftime.c EOF echo - 'date.1' cat << 'EOF' > 'date.1' .TH DATE 1 .SH NAME date \- write the date and time .SH SYNOPSIS .B date [ .B \-u ] [ .RI + format ] .SH DESCRIPTION .I Date writes the current date and time to the standard output. It is intended to be compliant with draft 11 of the Posix 1003.2 Command Language and Utilities standard. Therefore, it is purposely .I not usable by the super-user for setting the system time. .LP .I Date accepts one option: .TP .B \-u Perform operations as if the .B TZ environment variable was set to .BR GMT0 . .LP If an argument to .I date is given that begins with a ``+'', then the output is controlled by the contents of the rest of the string. Normal text is output unmodified, while field descriptors in the format string are substituted for. .LP The .I date program is essentially a wrapper around .IR strftime (3); see there for a description of the available formatting options. .LP If no format string is given, or if it does not begin with a ``+'', then the default format of \fB"%a %b %e %H:%M:%S %Z %Y"\fR will be used. This produces the traditional style of output, such as ``Sun Mar 17 10:32:47 EST 1991''. .SH SEE ALSO time(2), strftime(3), localtime(3) .SH BUGS This version only works for the POSIX locale. .SH AUTHOR .nf Arnold Robbins .sp INTERNET: arnold(a)skeeve.atl.ga.us UUCP: emory!skeeve!arnold Phone: +1 404 248 9324 .fi EOF echo - 'date.c' cat << 'EOF' > 'date.c' /* * date.c * * Public domain implementation of Posix 1003.2 * date command. Lets strftime() do the dirty work. * * Arnold Robbins * arnold(a)skeeve.atl.ga.us * April, 1991 * * Bug fix courtesy of Chris Ritson (C.R.Ritson(a)newcastle.ac.uk) * February, 1994. */ #include <stdio.h> #include <sys/types.h> #include <time.h> extern char *malloc(); extern size_t strftime(); extern int getopt(); extern int optind; int main(argc, argv) int argc; char **argv; { time_t clock; struct tm *now; int c, size, ret; char *defhow = "%a %b %e %H:%M:%S %Z %Y"; char *howto = defhow; char *buf; while ((c = getopt(argc, argv, "u")) != -1) switch (c) { case 'u': putenv("TZ=GMT0"); break; default: fprintf(stderr, "usage: %s [-u] [+format_str]\n", argv[0]); exit(1); } time(& clock); now = localtime(& clock); if (optind < argc && argv[optind][0] == '+') howto = & argv[optind][1]; size = strlen(howto) * 10; if (size < 26) size = 26; if ((buf = malloc(size)) == NULL) { perror("not enough memory"); exit(1); } ret = strftime(buf, size, howto, now); if (ret != 0) printf("%s\n", buf); else { fprintf(stderr, "conversion failed\n"); exit(1); } exit(0); } EOF echo - 'strftime.3' cat << 'EOF' > 'strftime.3' .TH STRFTIME 3 .SH NAME strftime \- generate formatted time information .SH SYNOPSIS .ft B .nf #include <sys/types.h> #include <time.h> .sp size_t strftime(char *s, size_t maxsize, const char *format, const struct tm *timeptr); .SH DESCRIPTION The following description is transcribed verbatim from the December 7, 1988 draft standard for ANSI C. This draft is essentially identical in technical content to the final version of the standard. .LP The .B strftime function places characters into the array pointed to by .B s as controlled by the string pointed to by .BR format . The format shall be a multibyte character sequence, beginning and ending in its initial shift state. The .B format string consists of zero or more conversion specifiers and ordinary multibyte characters. A conversion specifier consists of a .B % character followed by a character that determines the behavior of the conversion specifier. All ordinary multibyte characters (including the terminating null character) are copied unchanged into the array. If copying takes place between objects that overlap the behavior is undefined. No more than .B maxsize characters are placed into the array. Each conversion specifier is replaced by appropriate characters as described in the following list. The appropriate characters are determined by the .B LC_TIME category of the current locale and by the values contained in the structure pointed to by .BR timeptr . .TP .B %a is replaced by the locale's abbreviated weekday name. .TP .B %A is replaced by the locale's full weekday name. .TP .B %b is replaced by the locale's abbreviated month name. .TP .B %B is replaced by the locale's full month name. .TP .B %c is replaced by the locale's appropriate date and time representation. .TP .B %d is replaced by the day of the month as a decimal number .RB ( 01 - 31 ). .TP .B %H is replaced by the hour (24-hour clock) as a decimal number .RB ( 00 - 23 ). .TP .B %I is replaced by the hour (12-hour clock) as a decimal number .RB ( 01 - 12 ). .TP .B %j is replaced by the day of the year as a decimal number .RB ( 001 - 366 ). .TP .B %m is replaced by the month as a decimal number .RB ( 01 - 12 ). .TP .B %M is replaced by the minute as a decimal number .RB ( 00 - 59 ). .TP .B %p is replaced by the locale's equivalent of the AM/PM designations associated with a 12-hour clock. .TP .B %S is replaced by the second as a decimal number .RB ( 00 - 61 ). .TP .B %U is replaced by the week number of the year (the first Sunday as the first day of week 1) as a decimal number .RB ( 00 - 53 ). .TP .B %w is replaced by the weekday as a decimal number .RB [ "0 " (Sunday)- 6 ]. .TP .B %W is replaced by the week number of the year (the first Monday as the first day of week 1) as a decimal number .RB ( 00 - 53 ). .TP .B %x is replaced by the locale's appropriate date representation. .TP .B %X is replaced by the locale's appropriate time representation. .TP .B %y is replaced by the year without century as a decimal number .RB ( 00 - 99 ). .TP .B %Y is replaced by the year with century as a decimal number. .TP .B %Z is replaced by the time zone name or abbreviation, or by no characters if no time zone is determinable. .TP .B %% is replaced by .BR % . .LP If a conversion specifier is not one of the above, the behavior is undefined. .SH RETURNS If the total number of resulting characters including the terminating null character is not more than .BR maxsize , the .B strftime function returns the number of characters placed into the array pointed to by .B s not including the terminating null character. Otherwise, zero is returned and the contents of the array are indeterminate. .SH NON-ANSI EXTENSIONS If .B SYSV_EXT is defined when the routine is compiled, then the following additional conversions will be available. These are borrowed from the System V .IR cftime (3) and .IR ascftime (3) routines. .TP .B %D is equivalent to specifying .BR %m/%d/%y . .TP .B %e is replaced by the day of the month, padded with a blank if it is only one digit. .TP .B %h is equivalent to .BR %b , above. .TP .B %n is replaced with a newline character (\s-1ASCII LF\s+1). .TP .B %r is equivalent to specifying .BR "%I:%M:%S %p" . .TP .B %R is equivalent to specifying .BR %H:%M . .TP .B %T is equivalent to specifying .BR %H:%M:%S . .TP .B %t is replaced with a \s-1TAB\s+1 character. .PP If .B SUNOS_EXT is defined when the routine is compiled, then the following additional conversions will be available. These are borrowed from the SunOS version of .IR strftime . .TP .B %k is replaced by the hour (24-hour clock) as a decimal number .RB ( 0 - 23 ). Single digit numbers are padded with a blank. .TP .B %l is replaced by the hour (12-hour clock) as a decimal number .RB ( 1 - 12 ). Single digit numbers are padded with a blank. .SH POSIX 1003.2 EXTENSIONS If .B POSIX2_DATE is defined, then all of the conversions available with .B SYSV_EXT and .B SUNOS_EXT are available, as well as the following additional conversions: .TP .B %C The century, as a number between 00 and 99. .TP .B %u is replaced by the weekday as a decimal number .RB [ "1 " (Monday)- 7 ]. .TP .B %V is replaced by the week number of the year (the first Monday as the first day of week 1) as a decimal number .RB ( 01 - 53 ). The method for determining the week number is as specified by ISO 8601 (to wit: if the week containing January 1 has four or more days in the new year, then it is week 1, otherwise it is week 53 of the previous year and the next week is week 1). .LP The text of the POSIX standard for the .I date utility describes .B %U and .B %W this way: .TP .B %U is replaced by the week number of the year (the first Sunday as the first day of week 1) as a decimal number .RB ( 00 - 53 ). All days in a new year preceding the first Sunday are considered to be in week 0. .TP .B %W is replaced by the week number of the year (the first Monday as the first day of week 1) as a decimal number .RB ( 00 - 53 ). All days in a new year preceding the first Monday are considered to be in week 0. .LP In addition, the alternate representations .BR %Ec , .BR %EC , .BR %Ex , .BR %Ey , .BR %EY , .BR %Od , .BR %Oe , .BR %OH , .BR %OI , .BR %Om , .BR %OM , .BR %OS , .BR %Ou , .BR %OU , .BR %OV , .BR %Ow , .BR %OW , and .B %Oy are recognized, but their normal representations are used. .SH VMS EXTENSIONS If .B VMS_EXT is defined, then the following additional conversion is available: .TP .B %v The date in VMS format (e.g. 20-JUN-1991). .SH SEE ALSO .IR time (2), .IR ctime (3), .IR localtime (3), .IR tzset (3) .SH BUGS This version does not handle multibyte characters or pay attention to the setting of the .B LC_TIME environment variable. .LP It is not clear what is ``appropriate'' for the C locale; the values returned are a best guess on the author's part. .SH CAVEATS The pre-processor symbol .B POSIX_SEMANTICS is automatically defined, which forces the code to call .IR tzset (3) whenever the .B TZ environment variable has changed. If this routine will be used in an application that will not be changing .BR TZ , then there may be some performance improvements by not defining .BR POSIX_SEMANTICS . .SH AUTHOR .nf Arnold Robbins .sp INTERNET: arnold(a)skeeve.atl.ga.us UUCP: emory!skeeve!arnold Phone: +1 404 248 9324 .fi .SH ACKNOWLEDGEMENTS Thanks to Geoff Clare <gwc(a)root.co.uk> for helping debug earlier versions of this routine, and for advice about POSIX semantics. Additional thanks to Arthur David Olsen <ado(a)elsie.nci.nih.gov> for some code improvements. Thanks also to Tor Lillqvist <tml(a)tik.vtt.fi> for code fixes to the ISO 8601 code. EOF echo - 'strftime.c' cat << 'EOF' > 'strftime.c' /* * strftime.c * * Public-domain implementation of ANSI C library routine. * * It's written in old-style C for maximal portability. * However, since I'm used to prototypes, I've included them too. * * If you want stuff in the System V ascftime routine, add the SYSV_EXT define. * For extensions from SunOS, add SUNOS_EXT. * For stuff needed to implement the P1003.2 date command, add POSIX2_DATE. * For VMS dates, add VMS_EXT. * For complete POSIX semantics, add POSIX_SEMANTICS. * * The code for %c, %x, and %X is my best guess as to what's "appropriate". * This version ignores LOCALE information. * It also doesn't worry about multi-byte characters. * So there. * * This file is also shipped with GAWK (GNU Awk), gawk specific bits of * code are included if GAWK is defined. * * Arnold Robbins * January, February, March, 1991 * Updated March, April 1992 * Updated April, 1993 * Updated February, 1994 * * Fixes from ado(a)elsie.nci.nih.gov * February 1991, May 1992 * Fixes from Tor Lillqvist tml(a)tik.vtt.fi * May, 1993 * Further fixes from ado(a)elsie.nci.nih.gov * February 1994 */ #ifndef GAWK #include <stdio.h> #include <ctype.h> #include <string.h> #include <time.h> #endif #include <sys/types.h> #if defined(TM_IN_SYS_TIME) || ! defined(GAWK) #include <sys/time.h> #endif /* defaults: season to taste */ #define SYSV_EXT 1 /* stuff in System V ascftime routine */ #define SUNOS_EXT 1 /* stuff in SunOS strftime routine */ #define POSIX2_DATE 1 /* stuff in Posix 1003.2 date command */ #define VMS_EXT 1 /* include %v for VMS date format */ #ifndef GAWK #define POSIX_SEMANTICS 1 /* call tzset() if TZ changes */ #endif #if defined(POSIX2_DATE) #if ! defined(SYSV_EXT) #define SYSV_EXT 1 #endif #if ! defined(SUNOS_EXT) #define SUNOS_EXT 1 #endif #endif #if defined(POSIX2_DATE) #define adddecl(stuff) stuff #else #define adddecl(stuff) #endif #undef strchr /* avoid AIX weirdness */ #ifndef __STDC__ #define const /**/ extern void *malloc(); extern void *realloc(); extern void tzset(); extern char *strchr(); extern char *getenv(); static int weeknumber(); adddecl(static int iso8601wknum();) #else extern void *malloc(unsigned count); extern void *realloc(void *ptr, unsigned count); extern void tzset(void); extern char *strchr(const char *str, int ch); extern char *getenv(const char *v); static int weeknumber(const struct tm *timeptr, int firstweekday); adddecl(static int iso8601wknum(const struct tm *timeptr);) #endif #ifdef __GNUC__ #define inline __inline__ #else #define inline /**/ #endif #define range(low, item, hi) max(low, min(item, hi)) #if !defined(OS2) && !defined(MSDOS) && defined(HAVE_TZNAME) extern char *tzname[2]; extern int daylight; #endif /* min --- return minimum of two numbers */ #ifndef __STDC__ static inline int min(a, b) int a, b; #else static inline int min(int a, int b) #endif { return (a < b ? a : b); } /* max --- return maximum of two numbers */ #ifndef __STDC__ static inline int max(a, b) int a, b; #else static inline int max(int a, int b) #endif { return (a > b ? a : b); } /* strftime --- produce formatted time */ #ifndef __STDC__ size_t strftime(s, maxsize, format, timeptr) char *s; size_t maxsize; const char *format; const struct tm *timeptr; #else size_t strftime(char *s, size_t maxsize, const char *format, const struct tm *timeptr) #endif { char *endp = s + maxsize; char *start = s; auto char tbuf[100]; int i; static short first = 1; #ifdef POSIX_SEMANTICS static char *savetz = NULL; static int savetzlen = 0; char *tz; #endif /* POSIX_SEMANTICS */ /* various tables, useful in North America */ static const char *days_a[] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", }; static const char *days_l[] = { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", }; static const char *months_a[] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec", }; static const char *months_l[] = { "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December", }; static const char *ampm[] = { "AM", "PM", }; if (s == NULL || format == NULL || timeptr == NULL || maxsize == 0) return 0; /* quick check if we even need to bother */ if (strchr(format, '%') == NULL && strlen(format) + 1 >= maxsize) return 0; #ifndef POSIX_SEMANTICS if (first) { tzset(); first = 0; } #else /* POSIX_SEMANTICS */ tz = getenv("TZ"); if (first) { if (tz != NULL) { int tzlen = strlen(tz); savetz = (char *) malloc(tzlen + 1); if (savetz != NULL) { savetzlen = tzlen + 1; strcpy(savetz, tz); } } tzset(); first = 0; } /* if we have a saved TZ, and it is different, recapture and reset */ if (tz && savetz && (tz[0] != savetz[0] || strcmp(tz, savetz) != 0)) { i = strlen(tz) + 1; if (i > savetzlen) { savetz = (char *) realloc(savetz, i); if (savetz) { savetzlen = i; strcpy(savetz, tz); } } else strcpy(savetz, tz); tzset(); } #endif /* POSIX_SEMANTICS */ for (; *format && s < endp - 1; format++) { tbuf[0] = '\0'; if (*format != '%') { *s++ = *format; continue; } again: switch (*++format) { case '\0': *s++ = '%'; goto out; case '%': *s++ = '%'; continue; case 'a': /* abbreviated weekday name */ if (timeptr->tm_wday < 0 || timeptr->tm_wday > 6) strcpy(tbuf, "?"); else strcpy(tbuf, days_a[timeptr->tm_wday]); break; case 'A': /* full weekday name */ if (timeptr->tm_wday < 0 || timeptr->tm_wday > 6) strcpy(tbuf, "?"); else strcpy(tbuf, days_l[timeptr->tm_wday]); break; #ifdef SYSV_EXT case 'h': /* abbreviated month name */ #endif case 'b': /* abbreviated month name */ if (timeptr->tm_mon < 0 || timeptr->tm_mon > 11) strcpy(tbuf, "?"); else strcpy(tbuf, months_a[timeptr->tm_mon]); break; case 'B': /* full month name */ if (timeptr->tm_mon < 0 || timeptr->tm_mon > 11) strcpy(tbuf, "?"); else strcpy(tbuf, months_l[timeptr->tm_mon]); break; case 'c': /* appropriate date and time representation */ sprintf(tbuf, "%s %s %2d %02d:%02d:%02d %d", days_a[range(0, timeptr->tm_wday, 6)], months_a[range(0, timeptr->tm_mon, 11)], range(1, timeptr->tm_mday, 31), range(0, timeptr->tm_hour, 23), range(0, timeptr->tm_min, 59), range(0, timeptr->tm_sec, 61), timeptr->tm_year + 1900); break; case 'd': /* day of the month, 01 - 31 */ i = range(1, timeptr->tm_mday, 31); sprintf(tbuf, "%02d", i); break; case 'H': /* hour, 24-hour clock, 00 - 23 */ i = range(0, timeptr->tm_hour, 23); sprintf(tbuf, "%02d", i); break; case 'I': /* hour, 12-hour clock, 01 - 12 */ i = range(0, timeptr->tm_hour, 23); if (i == 0) i = 12; else if (i > 12) i -= 12; sprintf(tbuf, "%02d", i); break; case 'j': /* day of the year, 001 - 366 */ sprintf(tbuf, "%03d", timeptr->tm_yday + 1); break; case 'm': /* month, 01 - 12 */ i = range(0, timeptr->tm_mon, 11); sprintf(tbuf, "%02d", i + 1); break; case 'M': /* minute, 00 - 59 */ i = range(0, timeptr->tm_min, 59); sprintf(tbuf, "%02d", i); break; case 'p': /* am or pm based on 12-hour clock */ i = range(0, timeptr->tm_hour, 23); if (i < 12) strcpy(tbuf, ampm[0]); else strcpy(tbuf, ampm[1]); break; case 'S': /* second, 00 - 61 */ i = range(0, timeptr->tm_sec, 61); sprintf(tbuf, "%02d", i); break; case 'U': /* week of year, Sunday is first day of week */ sprintf(tbuf, "%02d", weeknumber(timeptr, 0)); break; case 'w': /* weekday, Sunday == 0, 0 - 6 */ i = range(0, timeptr->tm_wday, 6); sprintf(tbuf, "%d", i); break; case 'W': /* week of year, Monday is first day of week */ sprintf(tbuf, "%02d", weeknumber(timeptr, 1)); break; case 'x': /* appropriate date representation */ sprintf(tbuf, "%s %s %2d %d", days_a[range(0, timeptr->tm_wday, 6)], months_a[range(0, timeptr->tm_mon, 11)], range(1, timeptr->tm_mday, 31), timeptr->tm_year + 1900); break; case 'X': /* appropriate time representation */ sprintf(tbuf, "%02d:%02d:%02d", range(0, timeptr->tm_hour, 23), range(0, timeptr->tm_min, 59), range(0, timeptr->tm_sec, 61)); break; case 'y': /* year without a century, 00 - 99 */ i = timeptr->tm_year % 100; sprintf(tbuf, "%02d", i); break; case 'Y': /* year with century */ sprintf(tbuf, "%d", 1900 + timeptr->tm_year); break; case 'Z': /* time zone name or abbrevation */ #ifdef HAVE_TZNAME i = (daylight && timeptr->tm_isdst); /* 0 or 1 */ strcpy(tbuf, tzname[i]); #else strcpy(tbuf, timeptr->tm_zone); #endif break; #ifdef SYSV_EXT case 'n': /* same as \n */ tbuf[0] = '\n'; tbuf[1] = '\0'; break; case 't': /* same as \t */ tbuf[0] = '\t'; tbuf[1] = '\0'; break; case 'D': /* date as %m/%d/%y */ strftime(tbuf, sizeof tbuf, "%m/%d/%y", timeptr); break; case 'e': /* day of month, blank padded */ sprintf(tbuf, "%2d", range(1, timeptr->tm_mday, 31)); break; case 'r': /* time as %I:%M:%S %p */ strftime(tbuf, sizeof tbuf, "%I:%M:%S %p", timeptr); break; case 'R': /* time as %H:%M */ strftime(tbuf, sizeof tbuf, "%H:%M", timeptr); break; case 'T': /* time as %H:%M:%S */ strftime(tbuf, sizeof tbuf, "%H:%M:%S", timeptr); break; #endif #ifdef SUNOS_EXT case 'k': /* hour, 24-hour clock, blank pad */ sprintf(tbuf, "%2d", range(0, timeptr->tm_hour, 23)); break; case 'l': /* hour, 12-hour clock, 1 - 12, blank pad */ i = range(0, timeptr->tm_hour, 23); if (i == 0) i = 12; else if (i > 12) i -= 12; sprintf(tbuf, "%2d", i); break; #endif #ifdef VMS_EXT case 'v': /* date as dd-bbb-YYYY */ sprintf(tbuf, "%02d-%3.3s-%4d", range(1, timeptr->tm_mday, 31), months_a[range(0, timeptr->tm_mon, 11)], timeptr->tm_year + 1900); for (i = 3; i < 6; i++) if (islower(tbuf[i])) tbuf[i] = toupper(tbuf[i]); break; #endif #ifdef POSIX2_DATE case 'C': sprintf(tbuf, "%02d", (timeptr->tm_year + 1900) / 100); break; case 'E': case 'O': /* POSIX locale extensions, ignored for now */ goto again; case 'V': /* week of year according ISO 8601 */ #if defined(GAWK) && defined(VMS_EXT) { extern int do_lint; extern void warning(); static int warned = 0; if (! warned && do_lint) { warned = 1; warning( "conversion %%V added in P1003.2; for VMS style date, use %%v"); } } #endif sprintf(tbuf, "%02d", iso8601wknum(timeptr)); break; case 'u': /* ISO 8601: Weekday as a decimal number [1 (Monday) - 7] */ sprintf(tbuf, "%d", timeptr->tm_wday == 0 ? 7 : timeptr->tm_wday); break; #endif /* POSIX2_DATE */ default: tbuf[0] = '%'; tbuf[1] = *format; tbuf[2] = '\0'; break; } i = strlen(tbuf); if (i) { if (s + i < endp - 1) { strcpy(s, tbuf); s += i; } else return 0; } } out: if (s < endp && *format == '\0') { *s = '\0'; return (s - start); } else return 0; } #ifdef POSIX2_DATE /* iso8601wknum --- compute week number according to ISO 8601 */ #ifndef __STDC__ static int iso8601wknum(timeptr) const struct tm *timeptr; #else static int iso8601wknum(const struct tm *timeptr) #endif { /* * From 1003.2: * If the week (Monday to Sunday) containing January 1 * has four or more days in the new year, then it is week 1; * otherwise it is week 53 of the previous year, and the * next week is week 1. * * ADR: This means if Jan 1 was Monday through Thursday, * it was week 1, otherwise week 53. */ int weeknum, jan1day, diff; /* get week number, Monday as first day of the week */ weeknum = weeknumber(timeptr, 1); /* * With thanks and tip of the hatlo to tml(a)tik.vtt.fi * * What day of the week does January 1 fall on? * We know that * (timeptr->tm_yday - jan1.tm_yday) MOD 7 == * (timeptr->tm_wday - jan1.tm_wday) MOD 7 * and that * jan1.tm_yday == 0 * and that * timeptr->tm_wday MOD 7 == timeptr->tm_wday * from which it follows that. . . */ jan1day = timeptr->tm_wday - (timeptr->tm_yday % 7); if (jan1day < 0) jan1day += 7; /* * If Jan 1 was a Monday through Thursday, it was in * week 1. Otherwise it was last year's week 53, which is * this year's week 0. * * What does that mean? * If Jan 1 was Monday, the week number is exactly right, it can * never be 0. * If it was Tuesday through Thursday, the weeknumber is one * less than it should be, so we add one. * Otherwise, Friday, Saturday or Sunday, the week number is * OK, but if it is 0, it needs to be 53. */ switch (jan1day) { case 1: /* Monday */ break; case 2: /* Tuesday */ case 3: /* Wednedsday */ case 4: /* Thursday */ weeknum++; break; case 5: /* Friday */ case 6: /* Saturday */ case 0: /* Sunday */ if (weeknum == 0) weeknum = 53; break; } return weeknum; } #endif /* weeknumber --- figure how many weeks into the year */ /* With thanks and tip of the hatlo to ado(a)elsie.nci.nih.gov */ #ifndef __STDC__ static int weeknumber(timeptr, firstweekday) const struct tm *timeptr; int firstweekday; #else static int weeknumber(const struct tm *timeptr, int firstweekday) #endif { int wday = timeptr->tm_wday; int ret; if (firstweekday == 1) { if (wday == 0) /* sunday */ wday = 6; else wday--; } ret = ((timeptr->tm_yday + 7 - wday) / 7); if (ret < 0) ret = 0; return ret; } #if 0 /* ADR --- I'm loathe to mess with ado's code ... */ Date: Wed, 24 Apr 91 20:54:08 MDT From: Michal Jaegermann <audfax!emory!vm.ucs.UAlberta.CA!NTOMCZAK> To: arnold(a)audiofax.com Hi Arnold, in a process of fixing of strftime() in libraries on Atari ST I grabbed some pieces of code from your own strftime. When doing that it came to mind that your weeknumber() function compiles a little bit nicer in the following form: /* * firstweekday is 0 if starting in Sunday, non-zero if in Monday */ { return (timeptr->tm_yday - timeptr->tm_wday + (firstweekday ? (timeptr->tm_wday ? 8 : 1) : 7)) / 7; } How nicer it depends on a compiler, of course, but always a tiny bit. Cheers, Michal ntomczak(a)vm.ucs.ualberta.ca #endif #ifdef TEST_STRFTIME /* * NAME: * tst * * SYNOPSIS: * tst * * DESCRIPTION: * "tst" is a test driver for the function "strftime". * * OPTIONS: * None. * * AUTHOR: * Karl Vogel * Control Data Systems, Inc. * vogelke(a)c-17igp.wpafb.af.mil * * BUGS: * None noticed yet. * * COMPILE: * cc -o tst -DTEST_STRFTIME strftime.c */ /* ADR: I reformatted this to my liking, and deleted some unneeded code. */ #ifndef NULL #include <stdio.h> #endif #include <sys/time.h> #include <string.h> #define MAXTIME 132 /* * Array of time formats. */ static char *array[] = { "(%%A) full weekday name, var length (Sunday..Saturday) %A", "(%%B) full month name, var length (January..December) %B", "(%%C) Century %C", "(%%D) date (%%m/%%d/%%y) %D", "(%%E) Locale extensions (ignored) %E", "(%%H) hour (24-hour clock, 00..23) %H", "(%%I) hour (12-hour clock, 01..12) %I", "(%%M) minute (00..59) %M", "(%%O) Locale extensions (ignored) %O", "(%%R) time, 24-hour (%%H:%%M) %R", "(%%S) second (00..61) %S", "(%%T) time, 24-hour (%%H:%%M:%%S) %T", "(%%U) week of year, Sunday as first day of week (00..53) %U", "(%%V) week of year according to ISO 8601 %V", "(%%W) week of year, Monday as first day of week (00..53) %W", "(%%X) appropriate locale time representation (%H:%M:%S) %X", "(%%Y) year with century (1970...) %Y", "(%%Z) timezone (EDT), or blank if timezone not determinable %Z", "(%%a) locale's abbreviated weekday name (Sun..Sat) %a", "(%%b) locale's abbreviated month name (Jan..Dec) %b", "(%%c) full date (Sat Nov 4 12:02:33 1989)%n%t%t%t %c", "(%%d) day of the month (01..31) %d", "(%%e) day of the month, blank-padded ( 1..31) %e", "(%%h) should be same as (%%b) %h", "(%%j) day of the year (001..366) %j", "(%%k) hour, 24-hour clock, blank pad ( 0..23) %k", "(%%l) hour, 12-hour clock, blank pad ( 0..12) %l", "(%%m) month (01..12) %m", "(%%p) locale's AM or PM based on 12-hour clock %p", "(%%r) time, 12-hour (same as %%I:%%M:%%S %%p) %r", "(%%u) ISO 8601: Weekday as decimal number [1 (Monday) - 7] %u", "(%%v) VAX date (dd-bbb-YYYY) %v", "(%%w) day of week (0..6, Sunday == 0) %w", "(%%x) appropriate locale date representation %x", "(%%y) last two digits of year (00..99) %y", (char *) NULL }; /* main routine. */ int main(argc, argv) int argc; char **argv; { long time(); char *next; char string[MAXTIME]; int k; int length; struct tm *tm; long clock; /* Call the function. */ clock = time((long *) 0); tm = localtime(&clock); for (k = 0; next = array[k]; k++) { length = strftime(string, MAXTIME, next, tm); printf("%s\n", string); } exit(0); } #endif /* TEST_STRFTIME */ EOF

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Re: Standard for timezone handling with TZ
by ado Feb. 22, 1994

Feb. 22, 1994

Attached is my current best effort at dealing with "GMT" files in the time zone package. I'd very much welcome any feedback. --ado # @(#)etcetera 7.2 # All of these are set up just so people can "zic -l" to a timezone # that's right for their area, even if it doesn't have a name or DST rules # (half hour zones are too much to bother with -- when someone asks!) Zone GMT 0 - GMT Link GMT UTC Link GMT UCT Link GMT Universal Link GMT Greenwich Link GMT Zulu Link GMT GMT-0 Link GMT GMT+0 Link GMT GMT0 # We use POSIX-style signedness in the names and output, # internal-style signedness in the specifications. # These are shoved down into an "Etc" directory so we get a name change-- # in earlier incarnations, we had lines such as # Zone GMT-12 -12 - GMT-1200 # and do not want things to change quietly if someone accustomed to the old # way does a # zic -l GMT-12 Zone Etc/GMT-12 12 - GMT-12 Zone Etc/GMT-11 11 - GMT-11 Zone Etc/GMT-10 10 - GMT-10 Zone Etc/GMT-9 9 - GMT-9 Zone Etc/GMT-8 8 - GMT-8 Zone Etc/GMT-7 7 - GMT-7 Zone Etc/GMT-6 6 - GMT-6 Zone Etc/GMT-5 5 - GMT-5 Zone Etc/GMT-4 4 - GMT-4 Zone Etc/GMT-3 3 - GMT-3 Zone Etc/GMT-2 2 - GMT-2 Zone Etc/GMT-1 1 - GMT-1 Zone Etc/GMT+1 -1 - GMT+1 Zone Etc/GMT+2 -2 - GMT+2 Zone Etc/GMT+3 -3 - GMT+3 Zone Etc/GMT+4 -4 - GMT+4 Zone Etc/GMT+5 -5 - GMT+5 Zone Etc/GMT+6 -6 - GMT+6 Zone Etc/GMT+7 -7 - GMT+7 Zone Etc/GMT+8 -8 - GMT+8 Zone Etc/GMT+9 -9 - GMT+9 Zone Etc/GMT+10 -10 - GMT+10 Zone Etc/GMT+11 -11 - GMT+11 Zone Etc/GMT+12 -12 - GMT+12 Zone Etc/GMT+13 -13 - GMT+13 # GMT offset 12 hours with DST

2 1

Re: Standard for timezone handling with TZ
by ado Feb. 14, 1994

Feb. 14, 1994

> That's a bug in the Olson rules; they aren't compatible with Posix > 1003.1-1990. Thanks for pointing it out. Here's a conservative patch > to Olson's latest version which renames `GMT-4' to `GMT-0400' to avoid > the bug. > > Another possibility is simply to remove the GMT[-+]* rules, since their > sign is the opposite of the sign in the Posix TZ string, and this is confusing. My guess is it's best to keep some sort of GMT rules; as the etcetera file notes, # All of these are set up just so people can "zic -l" to a timezone # that's right for their area, even if it doesn't have a name or dst rules # (half hour zones are too much to bother with -- when someone asks!) and if you don't have the rules you can't do the "zic -l". (Whether there should be some mechanism to establish a rule-based rather than file-based time zone as local time is another question.) > *** etcetera 1992/04/23 17:34:35 7.1 > --- etcetera 1994/02/10 19:49:45 7.1.1.1 > *************** > *** 6,55 **** > > Zone GMT 0 - GMT > > ! Zone GMT-12 -12 - GMT-1200 > ! Zone GMT-11 -11 - GMT-1100 Is it better to render these as, for example, > Zone GMT 0 - GMT > > ! Zone GMT+1200 -12 - GMT+1200 > ! Zone GMT+1100 -11 - GMT+1100 Or, given Casper H. S. Dik's example... > SunOS 4: > % env TZ=GMT-4 date GMT-4 is a timezone file (Olson) > Thu Feb 10 04:29:42 GMT-0400 1994 > % env TZ=GMT-04 date But use POSIX rules here > Thu Feb 10 12:32:21 GMT 1994 ...does POSIX *require* that the above rules be written > Zone GMT 0 - GMT > > ! Zone GMT+1200 -12 - GMT > ! Zone GMT+1100 -11 - GMT (that is, without the "+1200" modifier to the zone name that will appear in user-visible output)? --ado

3 2

Re: Standard for timezone handling with TZ
by eggert＠twinsun.com Feb. 10, 1994

Feb. 10, 1994

In comp.unix.solaris Casper H.S. Dik writes: > SunOS 4: > % env TZ=GMT-4 date GMT-4 is a timezone file (Olson) > Thu Feb 10 04:29:42 GMT-0400 1994 > % env TZ=GMT-04 date But use POSIX rules here > Thu Feb 10 12:32:21 GMT 1994 That's a bug in the Olson rules; they aren't compatible with Posix 1003.1-1990. Thanks for pointing it out. Here's a conservative patch to Olson's latest version which renames `GMT-4' to `GMT-0400' to avoid the bug. Another possibility is simply to remove the GMT[-+]* rules, since their sign is the opposite of the sign in the Posix TZ string, and this is confusing. *** etcetera 1992/04/23 17:34:35 7.1 --- etcetera 1994/02/10 19:49:45 7.1.1.1 *************** *** 6,55 **** Zone GMT 0 - GMT ! Zone GMT-12 -12 - GMT-1200 ! Zone GMT-11 -11 - GMT-1100 ! Zone GMT-10 -10 - GMT-1000 ! Zone GMT-9 -9 - GMT-0900 ! Zone GMT-8 -8 - GMT-0800 ! Zone GMT-7 -7 - GMT-0700 ! Zone GMT-6 -6 - GMT-0600 ! Zone GMT-5 -5 - GMT-0500 ! Zone GMT-4 -4 - GMT-0400 ! Zone GMT-3 -3 - GMT-0300 ! Zone GMT-2 -2 - GMT-0200 ! Zone GMT-1 -1 - GMT-0100 ! Zone GMT+1 1 - GMT+0100 ! Zone GMT+2 2 - GMT+0200 ! Zone GMT+3 3 - GMT+0300 ! Zone GMT+4 4 - GMT+0400 ! Zone GMT+5 5 - GMT+0500 ! Zone GMT+6 6 - GMT+0600 ! Zone GMT+7 7 - GMT+0700 ! Zone GMT+8 8 - GMT+0800 ! Zone GMT+9 9 - GMT+0900 ! Zone GMT+10 10 - GMT+1000 ! Zone GMT+11 11 - GMT+1100 ! Zone GMT+12 12 - GMT+1200 ! Zone GMT+13 13 - GMT+1300 # GMT+12 with DST Link GMT UTC Link GMT UCT Link GMT Universal Link GMT Greenwich Link GMT Zulu ! Link GMT GMT-0 ! Link GMT GMT+0 ! Link GMT GMT0 ! Link GMT+1 GMT1 ! Link GMT+2 GMT2 ! Link GMT+3 GMT3 ! Link GMT+4 GMT4 ! Link GMT+5 GMT5 ! Link GMT+6 GMT6 ! Link GMT+7 GMT7 ! Link GMT+8 GMT8 ! Link GMT+9 GMT9 ! Link GMT+10 GMT10 ! Link GMT+11 GMT11 ! Link GMT+12 GMT12 ! Link GMT+13 GMT13 --- 6,41 ---- Zone GMT 0 - GMT ! Zone GMT-1200 -12 - GMT-1200 ! Zone GMT-1100 -11 - GMT-1100 ! Zone GMT-1000 -10 - GMT-1000 ! Zone GMT-0900 -9 - GMT-0900 ! Zone GMT-0800 -8 - GMT-0800 ! Zone GMT-0700 -7 - GMT-0700 ! Zone GMT-0600 -6 - GMT-0600 ! Zone GMT-0500 -5 - GMT-0500 ! Zone GMT-0400 -4 - GMT-0400 ! Zone GMT-0300 -3 - GMT-0300 ! Zone GMT-0200 -2 - GMT-0200 ! Zone GMT-0100 -1 - GMT-0100 ! Zone GMT+0100 1 - GMT+0100 ! Zone GMT+0200 2 - GMT+0200 ! Zone GMT+0300 3 - GMT+0300 ! Zone GMT+0400 4 - GMT+0400 ! Zone GMT+0500 5 - GMT+0500 ! Zone GMT+0600 6 - GMT+0600 ! Zone GMT+0700 7 - GMT+0700 ! Zone GMT+0800 8 - GMT+0800 ! Zone GMT+0900 9 - GMT+0900 ! Zone GMT+1000 10 - GMT+1000 ! Zone GMT+1100 11 - GMT+1100 ! Zone GMT+1200 12 - GMT+1200 ! Zone GMT+1300 13 - GMT+1300 # GMT+12 with DST Link GMT UTC Link GMT UCT Link GMT Universal Link GMT Greenwich Link GMT Zulu ! Link GMT GMT-0000 ! Link GMT GMT+0000

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