Ubuntu – Why does tasksel exist when there are already meta packages

These packages do not contain actual software, they simply depend on other packages to be installed.

It is important to note that removing a meta package does NOT remove the packages it installed:

when a metapackage is automatically removed by the removal or purging of any one, or more, of its underlying dependencies, all of the other packages that were in the metapackage's depends list are still installed on the system.

You can look at the structure of a typical meta package by pulling (for example) ubuntu-desktop:

apt-get source ubuntu-desktop

and then looking at the structure, you'll find the list of packages each meta-package recommends, as well as the structure of putting it all together in debian/rules.

References:

• https://help.ubuntu.com/community/MetaPackages
• How to create a meta-package that automatically installs other packages?

There are three basic ways an Ubuntu package can depend or pull in other packages:

1. Depends - this is a hard dependency, the program you are installing requires this other package to run. If you try to uninstall one of these packages, your program will be uninstalled with it.
2. Recommends - this is a package the is needed or recommended for normal use of the program you are installing, but the program will work without it. By default Ubuntu will install these (unless disabled with --no-install-recommends) but it won't complain if you remove them later on.
3. Suggests - this is a package that can enhance the program you are installing but is not considered a part of normal use. These packages are not installed by default (unless enabled with --install-suggests) and would be considered like a "hey, you might find these interesting" from the package developer.

By default, Ubuntu installs packages marked as depends and recommends, and all these will be listed as extra packages, unless you specified some of them explicitly on the command line.

Packages marked as NEW are all the packages that are about to be installed, i.e. the packages specified on the command line and all extra packages.