Ubuntu still says packages need updating following update

Question

I did sudo apt-get update and sudo apt-get upgrade which resulted in:

Hit http://security.ubuntu.com saucy-security/universe Translation-en
Ign http://security.ubuntu.com saucy-security/main Translation-en_US
Ign http://security.ubuntu.com saucy-security/universe Translation-en_US
Fetched 8,843 kB in 6s (1,422 kB/s)                                                                                                                                                               
Reading package lists... Done
ubuntu@core01:~$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages have been kept back:
  linux-headers-generic linux-headers-virtual linux-image-virtual linux-virtual python3-distupgrade ubuntu-release-upgrader-core
0 upgraded, 0 newly installed, 0 to remove and 6 not upgraded.
ubuntu@core01:~$ 

so I then did:

sudo do-release-upgrade
Checking for a new Ubuntu release
No new release found

and next time I logged in:

  Get cloud support with Ubuntu Advantage Cloud Guest:
    http://www.ubuntu.com/business/services/cloud

  Use Juju to deploy your cloud instances and workloads:
    https://juju.ubuntu.com/#cloud-saucy

24 packages can be updated.
9 updates are security updates.

Can anyone suggest which it still says 24 packages need updating?

thanks

Answer 1

Better answer than I could type out here: https://askubuntu.com/questions/601/the-following-packages-have-been-kept-back-why-and-how-do-i-solve-it

do-release-upgrade is for stepping between major releases in Ubuntu. Despite the similar sounding name apt-get dist-upgrade just allows for new and changing depends to be handled. Sometimes this is part of an upgrade from one version of Debian/Ubuntu to the next but just as often it is for when you are following testing/unstable and the packaging changes.