It seems python3-pip is not installed correctly on my system so I did

sudo apt install --reinstall python3-pip

Now I can install programs with pip3.

It looks like your package mirror (lnx-solutions) doesn't have the package. I would choose a different mirror and see if that helps. I've had this happen before as well with mirrors like this one

Try this command

sudo apt-get install python3-pip

Note: If you have a fresh install, you need to do this first before trying the above command.

sudo apt-get update

Installing pip for Python 3** Ubuntu 18.04 ships with Python 3, as the default Python installation. Complete the following steps to install pip ( pip3 ) for Python 3: Start by updating the package list using the following command: sudo apt update Use the following command to install pip for Python 3: sudo apt install python3-pip The command above will also install all the dependencies required for building Python modules. Once the installation is complete, verify the installation by checking

I will appreciate if someone could explain the differences (if any) between:

Highest level: you never should use pip install to install to system (--system, or on Linux distros where --user isn't the default, omitting --user) when things might conflict with your system whereas apt install is pretty safe.

Explanation:

apt is the package installation tool of your Linux distro. A Linux distribution these days is mostly the effort to offer a way to install packages in a way that works with each other without breaking – for example, if you're trying to install a library that libreoffice uses, but in a version incompatible with your libreoffice, your linux distro tool will tell you that sadly, to fulfill your command, it will have to uninstall libreoffice, because it wouldn't work with that version you're requesting.

The fact that you very rarely see that happen is an indication of how well modern Linux distros are doing here: typically, most of software that you can install using apt works well together.

pip, on the other hand, has no notion of what other software you have on your machine, which you might need. You tell pip to install something in a version that breaks your ability to even boot your system – it will go ahead and do that.

pip is python-specific. It assumes that all there is on that machine that has something to do with Python is kind of "fair game" and can be dealt with arbitrarily. Frankly, that is almost never the case – for example, on Fedora (another Linux distro that you're not using), you can easily break the installation tool dnf (Fedora's apt, if you will) with pip.

So, why does pip still exist? Well, there are situation where it's OK for pip to assume every bit of python it sees is under its control: Python brings a mechanism called virtual environments. In these, no python modules are per se installed, and they don't conflict with other software on your machine – simply because other software isn't aware of the environment.

Using that is quite straightforward. You can set up such an environment using

python3 -m venv ~/bertsexperiment

That sets up a folder ~/bertsexperiment for Python stuff to be installed into. You can then, from anywhere you like, "activate" that environment (what that really does is just change a few environment variables) – but that only affects the current process and things started from it. Try it:

source ~/bertsexperiment/bin/activate

will set up this shell in a way that all future python tooling will work with that folder as "prefix".

For example, if you wanted to have an updated setuptools in that shell, you could, after sourceing the activaton script as shown above, run pip3 install --upgrade setuptools, and they would be installed into the virtualenv.

In short:

• if in doubt, use apt, because it's your distro's job to keep your software stack working together
• Never use pip unless you intend to install something into a folder only used for your current project and not by anything else on your system.
  Hence, the only realistic time you would want to use it is when you're using a Python virtualenv.

One of three things will likely fix it:

1. In case python3-pip did not install correctly, re-install it:

   This is used for Debian-based distros like Ubuntu, Mint:

   sudo apt-get remove python3-pip; sudo apt-get install python3-pip
   

   If using Fedora, CentOS, RHEL, please use:

   sudo dnf reinstall python3-pip
   

2. Try using the command python3-pip instead (works on Fedora; I don't have a copy of Kubuntu to try it on).

3. Just a wild guess...check pip --version. There is a slight possibility that after installing python3-pip the new pip would replace the old pip (perhaps via alternatives?)

EDIT
Now that the output of dpkg -L python3-pip has been added to the question, I can provide the answer.

The correct command name to use is: pip-3.2.

Ubuntu 12.10+ and Fedora 13+ have a package called python3-pip which will install pip-3.2 (or pip-3.3, pip-3.4 or pip3 for newer versions) without needing this jumping through hoops.

---

I came across this and fixed this without needing the likes of wget or virtualenvs (assuming Ubuntu 12.04):

1. Install package python3-setuptools: run sudo aptitude install python3-setuptools, this will give you the command easy_install3.
2. Install pip using Python 3's setuptools: run sudo easy_install3 pip, this will give you the command pip-3.2 like kev's solution.
3. Install your PyPI packages: run sudo pip-3.2 install <package> (installing python packages into your base system requires root, of course).
4. …
5. Profit!