  Linux users expect fresh packages in the official repositories of their
distributions. Yet, due to philosophical divergences, the packages available in
various distributions do not all have the same degree of freshness. Users
therefore need to be informed as to those differences. Through quantitative
empirical analyses, we assess and compare the freshness of 890 common packages
in six mainstream Linux distributions. We find that at least one out of ten
packages is outdated, but the proportion of outdated packages varies greatly
between these distributions. Using the metrics of update delay and time lag, we
find that the majority of packages are using versions less than 3 months behind
the upstream in 5 of those 6 distributions. We contrast the user perception of
package freshness with our analyses and order the considered distributions in
terms of package freshness to help Linux users in choosing a distribution that
most fits their needs and expectations.
