General Support: session_save_path

I had no problem for few days, but now I cannot realy use admin. Agter I log in I get this error message:
Warning: Unknown: write failed: No space left on device (28) in Unknown on line 0

Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/tmp) in Unknown on line 0

I followed this recommendation:
So, try this. Open 'plogger/admin/index.php' and at the top is the session_start(); function. Edit is as follows:
session_save_path("your home directory path/cgi-bin/tmp");session_start();

but I don't have any of session_save_path in my /admin/index.php


Tx
Veronika