Re: VMS Software Bootcamp 2024

On 9/25/2024 8:19 AM, Simon Clubley wrote:

On 2024-09-24, Arne Vajhøj <arne@vajhoej.dk> wrote:

On 9/19/2024 8:22 AM, Simon Clubley wrote:

On 2024-09-18, Tom Wade <nospam@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