Three main configuration files control basic operations of a Postgresql server instance.
These files are all located in the default Postgresql data folder. You can edit them
using your text editor of choice,or using the admin pack that comes with pgAdmin.
postgresql.conf controls general settings,such as how much memory to allocate,
default storage location for new databases,which IPs Postgresql listens on,where
logs are stored,and so forth.
pg_hba.conf controls security. It manages access to the server,dictating which users
can login into which databases,which IPs or groups of IPs are permitted to connect
and the authentication scheme expected.
pg_ident.conf is the mapping file that maps an authenticated OS login to a Post-
gresql user. This file is used less often,but allows you to map a server account to
a Postgresql account. For example,people sometimes map the OS root account
to the postgre’s super user account. Each authentication line in pg_hba.conf can
use a different pg_ident.conf file.
If you are ever unsure where these files are located，
run the Example 2-1 query as a super user while connected to any of your databases.
select * from pg_settings
where category = 'File Locations'
"config_file";"/var/lib/pgsql/data/postgresql.conf"
"data_directory";"/var/lib/pgsql/data"
"external_pid_file";""
"hba_file";"/var/lib/pgsql/data/pg_hba.conf"
"ident_file";"/var/lib/pgsql/data/pg_ident.conf"
也可以用linux文件查找命令查找：
[root@localhost ~]# find / -name postgresql.conf
/usr/lib/tmpfiles.d/postgresql.conf
/var/lib/pgsql/data/postgresql.conf
或者：
[root@localhost ~]# locate postgresql.conf
/usr/lib/tmpfiles.d/postgresql.conf
/usr/pgsql-9.4/share/postgresql.conf.sample
