#psql is the PostgreSQL terminal interface. The following commands were tested on version 9.5.
#Connection options:
#-U username (if not specified current OS user is used).
#-p port.
#-h server hostname/address.

#Connect to a specific database:
psql -U postgres -h serverAddress -d dbName

#Get databases on a server:
psql -U postgres -h serverAddress --list

#Execute sql query and save output to file:
#Add -t to get only rows as result.
psql -U postgres -d dbName -c 'select * from tableName;' -o 'fileName'

Read commands from file:
psql -f fileName

#Restore databases from file:
psql -f /fileName.backup postgres