
Some of the environment variables that are accepted by the Python interpreter can also be used to affect PL/Python behavior. They would need to be set in the environment of the main PostgreSQL server process, for example in a start script. The available environment variables depend on the version of Python; see the Python documentation for details. At the time of this writing, the following environment variables have an affect on PL/Python, assuming an adequate Python version:

-   `PYTHONHOME`
    
-   `PYTHONPATH`
    
-   `PYTHONY2K`
    
-   `PYTHONOPTIMIZE`
    
-   `PYTHONDEBUG`
    
-   `PYTHONVERBOSE`
    
-   `PYTHONCASEOK`
    
-   `PYTHONDONTWRITEBYTECODE`
    
-   `PYTHONIOENCODING`
    
-   `PYTHONUSERBASE`
    
-   `PYTHONHASHSEED`
    

(It appears to be a Python implementation detail beyond the control of PL/Python that some of the environment variables listed on the `python` man page are only effective in a command-line interpreter and not an embedded Python interpreter.)
