To create a system variable for a regular Axxon One server in Linux OS, do the following:

1. Stop the Axxon One server:
   

   sudo service axxon-one stop

2. Create a backup of the configuration:
   

   cp ~ngp/instance.conf ~ngp/instance.conf_bak

   This step is mandatory.

3. Open the server configuration file for editing:
   

   sudo nano ~ngp/instance.conf

4. Add the required variable as the first line in the configuration file:
   

   export %system_variable=value%

   For example, a variable to increase the export timeout:
   

   export NGP_EXPORT_TIMEOUT_MS=60000

5. After you make the changes and save the configuration file, start the Axxon One server:
   

   sudo service axxon-one start

As a result, the system variable is set permanently for the Axxon One server.