Using enviroment Variables with system.run

[1berto]

I'm trying to set and read a variable on Linux hosts (that run the agent).But when i try to read it, get nothing...
AllowRoot is enabled.

"system.run[ echo test ]"
"system.run[ export variable=test ]"
"system.run[ echo $variable ]"

With zabbix_get First command print test, third print nothing

Any clues?