[Info-vax] VMS Software Bootcamp 2024

[Arne Vajhøj]

On 9/25/2024 8:19 AM, Simon Clubley wrote:
> On 2024-09-24, Arne Vajhøj <arne at vajhoej.dk> wrote:
>> On 9/19/2024 8:22 AM, Simon Clubley wrote:
>>> On 2024-09-18, Tom Wade <nospam at void.blackhole.mx> wrote:
>>>> On 2024-09-18 00:25, Lawrence D'Oliveiro wrote:
>>>>
>>>>> But it?s not ISO 8601.
>>>>
>>>> Very true, but better than the AM/PM stuff, and unambiguous (unlike
>>>> mm/dd/yy or dd/mm/yy).
>>>
>>> VMS date/time formats are much more readable, but the main problem with
>>> VMS timekeeping is that it doesn't have a local timezone offset from a base
>>> GMT/UTC timepoint built into it.
>>
>> What is SYS$TIMEZONE_DIFFERENTIAL then?
> 
> A joke. At least when compared to Unix.

It exist. Joke or not.

 > VMS commands have no support for showing the active timezone.
 > Compare the output of the Linux date command with $ SHOW TIME.

$ SHOW TIME

does not display it.

But:

$ @sys$manager:utc$time_setup show

does.

> In Unix, all timestamps are based on GMT/UTC and the user's timezone is
> just an attribute of the user's process, which is the system timezone by
> default but can be changed by the user. Different processes can have
> different timezones and none of this affects what timestamp is actually
> written to the filesystem when the file changes.

> Compare the output of the Linux "ls --full" command with $ DIR/FULL.
> Note out the Linux command shows the timezone, and note how the timezone
> changes for each file depending on whether DST was active or not when the
> file was last modified.

All the stuff that existed before VMS 6.x (which obviously include DCL
the file stuff) is not time zone aware.

I am sure Hoff would say a few things about the curse of backwards
compatibility here.

But you can make your applications use UTC and timezone since VMS 6.x.

Arne