What does the "apt-get dselect-upgrade" command do?

When running the command apt-get I got all the possible options and commands for apt-get. But one of these commands and definitions I have not seen before:

dselect-upgrade - Follow dselect selections

I ran the command sudo apt-get dselect-upgrade just to see what happened and this was the output:

Reading package lists... Done
Building dependency tree
Reading state information... Done
0 to upgrade, 0 to newly install, 0 to remove and 0 not to upgrade.

So what does this command actually do? And what does it mean to Follow dselect sections?

3 Answers

As others have pointed out, it "follows dselect choices". One nice thing about this, is one can feed a list of packages selections to dpkg:

dpkg --clear-selections
dpkg --set-selections < package_choice_list

then do "apt-get dselect-upgrade" and it will remove anything not in the list, and install everything in the list. I don't think any other package tool can do that. It gives one a way to ensure "these and only these" packages are installed, which is very convenient.

Source: man apt-get

dselect-upgrade dselect-upgrade is used in conjunction with the traditional Debian packaging front-end, dselect(1). dselect-upgrade follows the changes made by dselect(1) to the Status field of available packages, and performs the actions necessary to realize that state (for instance, the removal of old and the installation of new packages).

So the question you're really after is "What is dselect?" and this used to be a way to use the capacity of Debian packages for suggesting other packages for installation back when dinosaurs used to roam the Earth. It does still work and even has its niches where it's still used, but nowadays there are easier ways to accomplish the same thing.

For a beginner's tutorial, look here.

What I know is that dselect is used in backing up our system.

You can also use it to install the same packages in any other system as yours.

dpkg --get-selection > packages.list This will create a list of all the packages installed in your system in the packages.list file.

Now, if something happens and your system crashes, you can install all the packages which were in your system with the help of this packages.list file.

dpkg --set-selections < packages.list

sudo apt-get dselect-upgrade

This will do the thing for you. It will install all the packages which were in your system before.

If you want to install same packages on your another system, then transfer this file to that system, and run those 2 commands. It will do the trick for you.