The postgres.conf file is located here: /etc/postgresql/9.1/main/postgres.conf. In postgres.conf can see a line stating data_directory=<path>
This is the directory where your database files are stored
Alternatively when you are connected to database use
to show the directory where your data is stored.
ps auxw|grep postgres|grep -- -D
/usr/lib/postgresql/9.3/bin/postgres -D /var/lib/postgresql/9.3/main -c config_file=/etc/postgresql/9.3/main/postgresql.conf
on Ubuntu 14.04. That command will work on other variants like Fedora
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