Uninstall OpenCV 4.2.0 and its Libraries

Question

I'm quite new to Ubuntu and I just installed opencv and some additional libraries using

sudo apt update
sudo apt install libopencv-dev python3-opencv sudo apt install libjpeg-dev libpng-dev libtiff-dev

I'm now trying to downgrade from opencv 4.2.0 to opencv 4.1.1.26.

How can I do this?

Solution

You uninstall using the same tool you used to install. Simply use 'remove' instead of 'install'. Apt does the cleanup -- proper cleanup is a fundamental job of a package manager.

So based on what you installed:

sudo apt remove libopencv-dev python3-opencv
sudo apt remove libjpeg-dev libpng-dev libtiff-dev
sudo apt autoremove

• You don't need to update your database of available packages in the repository, since you are removing packages instead of installing.

• If you want to remove settings files in /etc, use purge instead of remove.

• Files in your /home, if any, are NEVER removed by apt. You must delete those yourself.

• autoremove removes orphaned packages, if any. An "orphaned" package is neither explicitly installed by the user nor a dependency of other packages on the system.

Note: These are not magic incantations. Each command in the sequence does something specific. Make sure you understand each command before running it. ALWAYS read and understand the output before agreeing to any changes.

Comments

[Ziad El-Massik]

I'm trying to uninstall opencv 4.2.0 so I can then re-install opencv as version 4.1.1.26. @user535733

[Ziad El-Massik]

Is it not possible to use pip install opencv-python==4.1.1.26 in the case of python 3.8 (After uninstalling the current opencv version, that is)?

[guiverc]

Also asked at ubuntuforums.org/showthread.php?t=2462486

[Ziad El-Massik]

@guiverc , that's my question there as well.

[Ziad El-Massik]

The problem isn't with the installation process but with how to do clean uninstallation of opencv and all opencv related libraries?

[Ziad El-Massik]

So let's say, I had other additional libraries for opencv besides those 3. If I use both purge and remove like this: sudo apt purge remove libopencv-dev python3-opencv . Will this remove all those libraries along with opencv or would I have to do something else?

[user535733]

Use apt's --simulate flag and see for yourself.

[Ziad El-Massik]

I just tested out sudo apt purge libopencv-dev python3-opencv --simulate. I later simulated sudo apt autoremove --simulate. They showed only the core libopencv libraries being uninstalled. However, the additional libraries were not shown. Is there a way I can purge all the additional libraries without knowing the details of these libraries (their names and how many were installed)?

[user535733]

That's what autoremove is for. If autoremove does not remove anything else, then some other package on your system depends upon those libraries (they are not orphaned).

[Ziad El-Massik]

Thank you so much for your help. This was very helpful. If you don't mind, I just have one more question. If I uninstall opencv (4.2.0) and reinstall an older version (4.1.1.26) and NOT uninstall the additional libraries, would the additional libraries like libjpeg-dev, work with the older opencv version or would they also have to be uninstalled and reinstalled?

[user535733]

Some libs will work, some won't. Best practice is to remove all libs for version X, so your version Y install will be clean.