From: Carlos Rodriguez (crodriguez@eliop.es)
Date: Mon Jul 14 2003 - 01:57:38 EDT
Hello managers. I received a new mail from Martin Moore relating to
this issue. It is not completely true that pre V5.0 versions do not
comply POSIX.1 standard. The difference between preV5.0 and postV5.0
is the sign orientation of the /etc/zoneinfo/GMT* time zone data
files.
This is the complete mail I received. I hope this helps.
> Carlos,
>
> I wanted to follow up my original response with some clarifying
> information (that I wasn't previously aware of either). I think you
> have most of this from Tom Peterson, but just in case, here it is:
>
> I originally wrote:
>
> > Tru64 UNIX V5.0 (and later) comply with the POSIX.1 standard
> > (ISO/IEC 9945-1 ANSI/IEEE Std. 1003.1), but earlier versions
> > do not
>
> Not true. Pre-V5.0 systems complied with POSIX.1 just fine.
> That is, the POSIX-defined format for TZ environment variable
> settings works the same on all Tru64 revs. ie: export TZ="GMT-3"
> yields the same results on pre-V5.0 and post-V5.0 systems. It's the
> implementation-defined format (the one with the leading ':') that's
> different (ie: export TZ=":GMT-3"). This TZ format is not defined by
> the POSIX standard, but is allowed as an implementation defined
> extension. The ':' format TZ references /etc/zoneinfo/ time zone data
> files, which did change between V4.* & V5.0, instead of just
> interpreting the TZ string, as is done with the POSIX format.
>
> In short, it's the sign orientation of the /etc/zoneinfo/GMT*
> time zone data files that changed, which has nothing to do with
> official POSIX compliance on Tru64, but was done to make these
> non-POSIX data file names "consistent" with the POSIX TZ strings
> of the same name. It was done so the following would yield the
> same results:
>
> implementation-defined format referencing time zone data files:
> $ export TZ=":GMT-3"
>
> standard POSIX format that hasn't changed:
> $ export TZ="GMT-3"
>
> But it wasn't a standards-compliancy issue.
>
> Similarly, regarding this statement:
>
> > So, GMT+1 in Tru64UNIX V4.0 is equal to GMT-1 in Tru64UNIX V5.0 (and
> > later).
>
> This could be a little misleading unless it's qualified.
> This statement only applies to the /etc/zoneinfo/GMT* time zone
> data files, not standard POSIX TZ strings, which are unchanged.
>
> Regards,
> Martin Moore
Summarizing:
I tested what Martin Moore wrote and this is what I have got:
Doing this:
# export TZ=GMT+1
# date
I have got the same results in 4.0F and 5.1A. In this case, GMT-1
is what I have got (as POSIX.1 defines).
But doing this:
# export TZ=:GMT+1
# date
Here is the difference. In 4.0F I have got GMT+1, but in 5.1A I
have got GMT-1, as POSIX.1 defines. So that is the really difference
working with dates between preV5.0 and postV5.0. This is related with
/etc/zoneinfo/GMT* files, which are the files I use to link to the
/etc/zoneinfo/localtime file.
Thanks to all.
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