QUESTION Hostname variable in dialplan

[Rrrr]

How can I use the current system name in the dialplan?
I dont manage to figure it out from here or here or here.
I want to use the same variable in the dialplan to get "mypbx" that makes up the system prompt: root@mypbx:~ $

Here is what I have tried:

...
same => n,NoOp(HOSTNAME: ${ENV(HOSTNAME)} PATH: ${ENV(H)} )
same => n,NoOp( SYSTEM: ${ENV(SYSTEMNAME)}/ ${SYSTEMNAME} ASTERISK_PROMPT: ${ENV(ASTERISK_PROMPT)}/${ASTERISK_PROMPT} Full hostname:${ENV(%h)}  Full hostname:${ENV(h)} Short hostname:${H}/${ENV(%H)}/${ENV(H)} Asterisk system name: ${ENV(%s)} ${ENV(s)} ) 
...

Thx