[tz] Iran DST change cancelled and step to avoid DST changing in their Linux system

[Paul Eggert]

On 3/16/22 06:17, S Sathish S via tz wrote:

> Customer running with Asia/Tehran (+0330, +0330) timezone, where Daylight saying is cancelled by their Iran government recently.

As I understand it, this decision is not final, so we haven't updated 
TZDB, although we plan to do so if and when it becomes final.


> Our Operator are requesting to avoid DST changing in their Linux system and expect tzdata patch from IANA (or) if possible any workaround to avoid this DST change in their systems.

If Iran's rules are changed and you're running a POSIX-compatible system 
whose TZDB instance has not been updated accordingly, you can work 
around some of the problem by using the time zone setting '<+0330>-3:30' 
instead of 'Asia/Tehran'. You can do this for a particular process by 
setting TZ='<+0330>-3:30' in the process's environment. To change the 
time zone globally you'll need to consult your system's documentation; 
for example, on the Fedora-based system that I'm typing this message on, 
the shell command:

   timedatectl set-timezone '<+0330>-3:30'

alters the /etc/localtime symbolic link to set the default time zone for 
processes that do not set TZ.

Unfortunately, using '<+0330>-3:30' mishandles some older timestamps and 
it might not work on non-POSIX systems. So a better fix will be to 
update TZDB.