\l 什么时候列出访问权限，什么时候不列出？\l 列出的访问权限可以在授予和撤销后更改：
$ createuser -EP my_readonly
$ psql development
development=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
-----------------------------+----------+----------+-------------+-------------+-----------------------
development | vagrant | UTF8 | en_GB.UTF-8 | en_GB.UTF-8 |
...
development=# grant usage on schema public to my_readonly;
development=# grant connect on database development to my_readonly;
development=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
-----------------------------+----------+----------+-------------+-------------+----------------------------
development | vagrant | UTF8 | en_GB.UTF-8 …