A call such as
fm <- glm(y ~ x1+x2, family=gaussian, data=sales)
achieves the same result as
fm <- lm(y ~ x1+x2, data=sales)
but much less efficiently. Note how the gaussian family is not automatically provided with a choice of links, so no parameter is allowed. If a problem requires a gaussian family with a nonstandard link, this can usually be achieved through the quasi family, as we shall see later.