code: def write_pgpass(self, name=None, site=None, use_sudo=0, root=0):
          
  
          r = self.database_renderer(name=name, site=site)
  
          root = int(root)
  
          use_sudo = int(use_sudo)
  
          r.run('touch {pgpass_path}')
          if '~' in r.env.pgpass_path:
              r.run('chmod {pgpass_chmod} {pgpass_path}')
          else:
              r.sudo('chmod {pgpass_chmod} {pgpass_path}')
  
          if root:
              r.env.shell_username = r.env.get('db_root_username', 'postgres')
              r.env.shell_password = r.env.get('db_root_password', 'password')
          else:
              r.env.shell_username = r.env.db_user
              r.env.shell_password = r.env.db_password
  
          r.append(
              '{db_host}:{port}:*:{shell_username}:{shell_password}',
              r.env.pgpass_path,
              use_sudo=use_sudo)
docs: Write the file used to store login credentials for PostgreSQL.