How to permanetly disable automatic package cache update after adding a PPA?

In recent releases of Ubuntu, adding a PPA automatically updates the package cache immediately.

Sometimes, I need to add several PPAs (e.g. after a new installation), and would like to manually run apt update in one go, after adding all the PPAs.

How to do that?

I found this question, which suggests using add-apt-repository -n ppa:user/repo.

How to change the default behavior so that the package cache will not be updated even when the -n flag is not supplied?

For example, in Linux Mint, the package cache is never automatically updated after adding a PPA. How to make that the default behavior in Ubuntu?

For system-wide method I would create local wrapper script placed into /usr/local/bin as follows

cat <<\EOF | sudo tee /usr/local/bin/add-apt-repository
#!/bin/bash
/usr/bin/add-apt-repository -n $@
EOF
sudo chmod +x /usr/local/bin/add-apt-repository

and do not forget about the apt-add-repository synonym command - run

sudo ln -s /usr/local/bin/add-apt-repository /usr/local/bin/apt-add-repository

Then use any of these commands with -n option auto-added.

Advanced Users

You can modify the source code to remove the apt update command.

Here is the code block you need to remove from the /usr/bin/add-apt-repository file:

        if update and not options.remove:
            os.execvp("apt-get", ["apt-get", "update"])
        sys.exit(0)

This will remove the update command.

NOTE: This piece of code comes two times in the file, you have to remove the LAST one. This piece of code in most files would be somewhere near line 198.

You can open the file using a text editor such as nano and remove this piece of code.

You can also modify the code a bit, something like:

        if update and not options.remove:
            os.execvp("apt-get", ["apt-get", "moo"])
        sys.exit(0)

NOTE: Edit this file with a terminal-text-editor like nano instead of GUI editors like gedit.

Beginners

Open a terminal using Ctrl + Alt + T

1. First, install nano:

   sudo apt update
   sudo apt install nano
   

2. Edit the file:

   sudo nano /usr/bin/add-apt-repository
   

3. Press the down arrow key repeatedly,unless you reached the end of the file.

4. You'll find an if statement which looks exactly like this:

           if update and not options.remove:
               os.execvp("apt-get", ["apt-get", "update"])
           sys.exit(0)   
   

5. Remove the whole if code block mentioned above.

6. Press Ctrl + X and then select Y and press ENTER.

Test

Restore the file

Messed up?

No worry! If we run dpkg -S on the file, we can see:

$ dpkg -S /usr/bin/add-apt-repository 
software-properties-common: /usr/bin/add-apt-repository

So just run:

sudo apt update
sudo cp -r /usr/bin/add-apt-repository /tmp
sudo rm -rf /usr/bin/add-apt-repository
sudo apt install software-properties-common --reinstall