What are the differences between apt clean/remove/purge etc. commands?

Question

I am quite new to Linux and Apt package manager. I try to build my first docker image (write my first Dockerfile) based on other Dockerfiles written by co-workers for other projects. I came across these commands and however I tried to google them separately one-by-one, as a Linux newbie I still don't really understand what are the differences between them or which one should I use or should I use them all together?

This is a piece from the Dockerfile:

RUN rm -rf /var/lib/apt/lists/*; \
    apt-get purge -y --auto-remove; \
    apt-get autoremove; \
    apt-get clean;

Could you please explain briefly what is the difference?

Answer 1

The differences between the command you metioned are described as follows. Hope these can help you a little.

apt remove

remove is identical to install except that packages are removed instead of installed.

It will remove the binaries, but leave configuration files, data files, and dependencies installed with it on installation time untouched.

apt purge

purge is identical to remove except that packages are removed and purged (any configuration files are deleted too).

It will remove about everything regarding the package, but not the dependencies installed with it on installation, which is particularly useful when you want to “start all over” with an application because you messed up the configuration.

However, purge won’t touch configuration or data files inside the user’s home folder (e.g. /home/User/hiddenFolders). There is no easy way to get those removed as well.

Note that other tools like aptitude will only remember dependency information for packages that it has installed.

apt autoremove

autoremove is used to remove packages that were automatically installed to satisfy dependencies for other packages and are now no longer needed.

In other words, it will only goes through the catalog and remove any left over packages that were not directly installed and that are not required by packages that are installed. Say that you install apache, it will install a lot of libraries. If you remove apache, all these libraries will be left behind until you run autoremove.

The only thing you should watch for, is if you started using one of the dependencies say “Python” but never actually installed it yourself; then it will be removed.

apt clean

clean clears out the local repository of retrieved package files. It removes everything but the lock file from /var/cache/apt/archives/ and /var/cache/apt/archieves/partial/.

apt autoclean

Like clean, autoclean clears out the local repository of retrieved package files. The difference is that it only removes package files that can no longer be downloaded, and are largely useless. This allows a cache to be maintained over a long period without it going out of control.

Extra

This part of contents is not closely related to the question, but I think it's necessary to give you some extra suggestions.

Do not remove files belonging to packages without using the package manager! 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

For some applications compiled from their source codes, the best way is to refer to its README, and remove it manually.