Setting timezone (no replies)

For setting timezone from CLI (unattended), I found that you need to update /etc/timezone and dpkg-reconfigure tzdata, something like this (from here:

$ echo "Australia/Adelaide" | sudo tee /etc/timezone
Australia/Adelaide 
$ sudo dpkg-reconfigure --frontend noninteractive tzdata

Current default time zone: 'Australia/Adelaide'
Local time is now:      Sat May  8 21:19:24 CST 2010.
Universal Time is now:  Sat May  8 11:49:24 UTC 2010.

When I do the same, it doesn't work:

 
admin@pogoplug:~$ echo Asia/Calcutta | sudo tee /etc/timezone
Asia/Calcutta
admin@pogoplug:~$ cat /etc/timezone
Asia/Calcutta
admin@pogoplug:~$ sudo dpkg-reconfigure -f noninteractive tzdata

Current default time zone: 'SystemV/PST8PDT'
Local time is now:      Sun Sep  3 05:08:23 PDT 2017.
Universal Time is now:  Sun Sep  3 12:08:23 UTC 2017.

admin@pogoplug:~$ cat /etc/timezone
SystemV/PST8PDT

The timezone simply gets reset. Anyone know how to get this working?