[Bug / Question ] " authentication_timeout " is invalid.

Hi, sir,

the "postgresql.conf" 's "authentication_timeout" is not active.

The Log:
-------------------------------------------------------------------------------------------------
[BEGIN] 2015/9/16 17:57:37
[postgres(at)pg95 ~]$ psql -V
psql (PostgreSQL) 9.5alpha2
[postgres(at)pg95 ~]$ time psql -c 'show authentication_timeout ;'
Password:
authentication_timeout
------------------------
1min
(1 row)
real 4m39.528s
user 0m0.003s
sys 0m0.002s

[END] 2015/9/16 18:03:10
---------------------------------------------------------------------------------------------------
The document is said :
From:

http://www.postgresql.org/docs/9.4/static/runtime-config-connection.html

authentication_timeout (integer)

Maximum time to complete client authentication, in seconds. If a would-be
client has not completed the authentication protocol in this much time, the
server closes the connection. This prevents hung clients from occupying a
connection indefinitely. The default is one minute (1m). This parameter can
only be set in the postgresql.conf file or on the server command line.

I can't find about this information or solution by goolge search or forum,
Please tell me how to verify it is active . or check it running?

Best Regards,

James Lin