$ uname -r
Package linux-headers-4.13.0-26-generic is not available, but is referred to by another package.that the package is missing, has been obsoleted, or
: Depends: linux-headers-generic (= 3.2.0.51.61) but 3.2.0.54.64 is to be installedii linux-headers-3.2.0-44-genericHeader files related to Linux kernel version 3.2.0
ii