What is the correct way to completely remove an application?

Question

I've searched the net for such information and found different command lines, like these ones:

sudo apt-get remove application
sudo apt-get remove application*

sudo apt-get remove --purge application
sudo apt-get remove --purge application*

sudo apt-get purge application
sudo apt-get purge application*

So, what is the correct way? Is it necessary to use that "*"?

After that, I also found these commands:

sudo updatedb
sudo locate application
sudo rm -rf (file/folder name)

Thanks for your time.

Answer 1

• apt-get remove packagename
  will remove the binaries, but not the configuration or data files of the package packagename. It will also leave dependencies installed with it on installation time untouched.
• apt-get purge packagename, or
  apt-get remove --purge packagename
  will remove about everything regarding the package packagename, but not the dependencies installed with it on installation. Both commands are equivalent.
  Particularly useful when you want to 'start all over' with an application because you messed up the configuration. However, it does not remove configuration or data files residing in your home directory, usually in hidden folders there. There is no easy way to get those removed as well.
• apt-get autoremove
  removes orphaned packages, i.e. installed packages that used to be installed as an dependency, but aren't any longer. Use this after removing a package which had installed dependencies you're no longer interested in.
• aptitude remove packagename, or
  aptitude purge packagename (likewise)
  will also attempt to remove then not used dependencies anymore in one step.

And many more exist. Lower-level dpkg-commands can be used (advanced), or GUI tools like Muon, Synaptic, Software Center, etc. There's no single 'correct way' of removing applications or performing other tasks interacting with your package management.

The list you found are just examples. Make sure you understand the meanings and try out what it wants to do before accepting the action (you need to press Y before it actually performs the actions as proposed).

The asterisk character appended just lets it expands to more packages starting with packagename. So if there's a packagename-common, packagename-gui and packagename they will match all three.

These commands,

sudo updatedb                  # <-- updates the locate database (index). harmless
sudo locate application        # <-- locates the file 'application'. harmless
sudo rm -rf (file/folder name) # <-- removes files/dirs recursively. dangerous.

are completely outside the scope of the package management. Do not remove files belonging to packages without using the package management! It will get confused and is the wrong way to do things.

If you don't know to which package a file belongs, try this:

dpkg -S /path/to/file

Answer 2

You can safely use sudo apt-get remove --purge application or sudo apt-get remove applications 99% of the time. When you use the purge flag, it simply removes all config files too. Which may or may not be what you want, depending on if you want to reinstall said application. The application* will match all applications that start with application, which are usually plugins, additional features, etc of the main application you are removing. i.e.

sudo apt-get remove gedit*

would remove gedit, gedit-plugins and gedit-common. Typically it is not necessary to do this, because most plugins/associated programs are dependent on the main application, and will automatically be removed (or marked for removal) when you uninstall the main application.

Your last command is just to remove leftovers from applications that are known to have messy uninstallers, and it is just removing any remnants of the application.

Answer 3

It depends on the application you want to remove. Always be sure to check its dependencies before issuing the yes command. When you remove something by command line, it will sometimes show a handful of libraries that are no longer needed. These can be removed with apt-get autoremove.

Beware that by using commands such as sudo apt-get remove --purge applicationname may remove some dependencies that are needed by other applications and, as such, might break your system.

If you want to do it in the safer way, you can always remove it using just the software center or apt-get remove applicationname. If the dependencies aren't needed anymore, issue apt-get autoremove later.

Answer 4

I found this command in internet.

dpkg --purge --force-depends application

http://www.debian-administration.org/article/Reinstalling_packages_to_fix_problems.