have to update on a regular basis...why?

[C de-Avillez]

On Sun, 08 Mar 2015 20:35:11 +1100
phil <phil at philfixit.info> wrote:


> >> sudo apt-get update && sudo apt-get upgrade && sudo apt-get
> >> dist-upgrade && sudo apt-get autoremove && sudo apt-get autoclean
> >> && exit
> >
> >
> > No need to run upgrade, dist-upgrade will do an upgrade plus
> > anything else it needs to do.
> >
> > Colin
> >
> Ah many thanks Colin, in fact a quick rtfm quickly located the 
> information, but for some reason i always thought there was a
> difference . . .
> 
> Phil
> 

There *is* a difference. From the man page for apt-get(1):

       upgrade
           upgrade is used to install the newest versions of all packages currently installed on the system from the sources enumerated in
           /etc/apt/sources.list. Packages currently installed with new versions available are retrieved and upgraded; under no circumstances are currently
           installed packages removed, or packages not already installed retrieved and installed. New versions of currently installed packages that cannot
           be upgraded without changing the install status of another package will be left at their current version. An update must be performed first so
           that apt-get knows that new versions of packages are available.

       dist-upgrade
           dist-upgrade in addition to performing the function of upgrade, also intelligently handles changing dependencies with new versions of packages;
           apt-get has a "smart" conflict resolution system, and it will attempt to upgrade the most important packages at the expense of less important
           ones if necessary. The dist-upgrade command may therefore remove some packages. The /etc/apt/sources.list file contains a list of locations from
           which to retrieve desired package files. See also apt_preferences(5) for a mechanism for overriding the general settings for individual
           packages.


So, in a very concise and incomplete sentence: 'upgrade' only updates
packages already installed, 'dist-upgrade' install new
dependencies/packages.

Usually, people (and very paranoid sysadmins) run 'apt-get upgrade' so
that no not-yet-installed package will be selected to be installed. The
usual impact is on the kernel: update kernels usually have a different
version string and, as a consequence, are considered not-yet-installed.

Cheers,

..C..
-- 
ab alio expectes alteri quod feceris
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