The connection service file allows libpq connection parameters to be
associated with a single service name. That service name can then be
specified by a libpq connection, and the associated settings will be
used. This allows connection parameters to be modified without requiring
a recompile of the libpq application. The service name can also be
specified using the PGSERVICE environment variable.
To use this feature, copy
share/pg_service.conf.sample to
etc/pg_service.conf and edit the file to add
service names and parameters. This file can be used for client-only
installs too. The file's location can also be specified by the
PGSYSCONFDIR environment variable.