Sudo apt install python3 pip ошибка

I installed Ubuntu 20.04 on a PC. I then tried to get started and install pip for python3. However nothing seemed to work.
This is what I have tried so far:

sudo apt install python3-pip

This is the error I get:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package python3-pip is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'python3-pip' has no installation candidate

I have tried the solution proposed by Carlos Sanchez JR.:
How to install Python package installer PIP on Ubuntu 20.04 Linux

After following the advice given in the link above I got this error when doing sudo apt update :

Ign:1 cdrom://Ubuntu 20.04 LTS _Focal Fossa_ - Release amd64 (20200423) focal InRelease
Hit:2 cdrom://Ubuntu 20.04 LTS _Focal Fossa_ - Release amd64 (20200423) focal Release
Hit:4 http://security.ubuntu.com/ubuntu focal-security InRelease              
Hit:6 http://archive.ubuntu.com/ubuntu focal InRelease                        
Get:5 http://kali.download/kali kali-rolling InRelease [30.5 kB]
Hit:7 http://archive.ubuntu.com/ubuntu focal-updates InRelease
Err:5 http://kali.download/kali kali-rolling InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY ED444FF07D8D0BF6
Get:8 http://kali.cs.nctu.edu.tw/kali kali-rolling InRelease [30.5 kB]
Err:8 http://kali.cs.nctu.edu.tw/kali kali-rolling InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY ED444FF07D8D0BF6
Reading package lists... Done
W: GPG error: http://kali.download/kali kali-rolling InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY ED444FF07D8D0BF6
E: The repository 'http://http.kali.org/kali kali-rolling InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: GPG error: http://kali.cs.nctu.edu.tw/kali kali-rolling InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY ED444FF07D8D0BF6
E: The repository 'http://kali.cs.nctu.edu.tw/kali kali-rolling InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

Trying sudo apt install python3-pip at this point just gives me the same E: Package 'python3-pip' has no installation candidate error as before. This is equally true when trying
sudo apt-get install python3-pip.

I have found no other solutions to this problem.

Introduction

Pip is a python library, package manager that allows you to download and install packages from the (Python Package Index) PyPi repository. When you try to download a package using the pip without having a pip package manager, an error will raise on the terminal window ‘pip: command not found.

In this guide, We will show you the main causes of this error and how to fix the pip command not found error on the Ubuntu 20.04 system using a potential solution.

What is “pip command not found” error ?

The python-pip package manager works as an independent package manager on Linux distribution. This means you need to install the pip tool separately from python programs.

The pip command is not found an error raised on your Linux terminal window if the pip is not installed independently on Ubuntu 20.04 system. Therefore, before installing any package using pip, the pip tool should be installed on your Ubuntu system.

ALSO READ: Install Nodejs and NPM on Raspberry Pi [Step-by-Step]

When are working with the python3 version, you can use the pip or pip3 as well while installing a new python package on your system.
For example, you want to install a python package ‘scrapy’ using the pip command:

$ pip3 install scrapy

The following pip: command not found error displays on the terminal. This means pip is not installed on your Ubuntu system.

How to fix pip command not found error on Ubuntu 20.04?

There can be two versions of pip (at the time of writing article python4 was not released so once python4 is available, it is possible we have another version of pip) i.e. from python2 and python3.

So based on your requirement and environment you can choose to install the respective pip version (although python2 is mostly deprecated and you can choose to install pip from Python3).

Scenario-1: Install pip package manager for Python3

When pip command not found error is raised on your terminal window, you can easily fix the error by running the below-mentioned command:

$ sudo apt install python3-pip

The above command will install the pip package manager on your Ubuntu 20.04 system as follows:

Display the pip installed version by using the following command:

$ pip --version
or
$ pip3 --version

ALSO READ: Install Sublime Text 4 on AlmaLinux 8 [Step-by-Step]

Now, you can go ahead an install a package using pip package manager by running the following command:

$ pip3 install scrapy

As you will notice, the above command will not show any error. It directly installs the scrapy python module on your system Ubuntu 20.04.

Scenario-2: Install pip package manager for Python2

Python 2 version has obsoleted now. This means Python 2 is no longer to use or maintained properly. Now, everyone moving towards the python 3 versions. So, try to move your python code over to the codebase that supports the newest Python 3 framework. But, if you still need to install the pip2 package manager tool then, download the get-pip.py script using the curl command as follows:

$ curl https://bootstrap.pypa.io/pip/2.7/get-pip.py --output get-pip.py

Now, you can install pip for the python2 version using the following command:

$ sudo python2 get-pip.py

Print the pip2 installed version using the below-mentioned command:

$ pip2 --version

How to use the pip command?

Using the pip command, you easily install packages from the python packages index repository, local projects, version control, and distribution files.
To get installation help related to python3 packages, use the following pip3command:

$ pip3 install --help

List all pip3 packages or modules

To list all pip3 packages, use the following command:

$ pip3 list

ALSO READ: How to Install PowerISO on Linux [Step-by-Step]

Install and uninstall a package using pip

Now, you can install a package from the pip3 packages list.

$ pip3 install package-name

Similarly, you can also uninstall it via pip3 or pip command. To uninstall a package using pip3, run the below-given command:

$ pip3 uninstall package-name

Upgrade a package using pip

You can also upgrade a specific package to its latest version using pip as follows:

$ pip install --upgrade package-name

Conclusion

We discussed two main reasons due to which the pip: command not found error raised. First, the pip is not installed on your Ubuntu system, or if two different python versions are installed on your system and you accidentally executed the pip command instead of pip3. Using the above-proposed solution I hope you can easily fix this error.

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Главная » Linux » Исправление “E: Invalid operation python3-pip” в Kali Linux

Опубликовано 29.11.2021

Иногда во время установки python3-pip в Kali Linux, появляется ошибка «E: Invalid operation python3-pip» (Недопустимая операция python3-pip). В этой короткой замети мы расскажем вам как исправить эту проблему.

E: Invalid operation python3-pip

Устранение ошибки «E: Invalid operation python3-pip»

Чтобы решить (исправить) ошибку «E: Invalid operation python3-pip», требуется всего лишь выполнить несколько простых команд по порядку.

echo "deb http://http.kali.org/kali kali-rolling main non-free contrib" | sudo tee /etc/apt/sources.list


sudo apt-get install software-properties-common


sudo add-apt-repository ppa:deadsnakes/ppa


sudo apt-get update


sudo apt-get install python3-pip

У вас должно получится тоже самое что и на скриншотах. Если есть замечания и предложения воспользуйтесь разделом комментарий.

Are you looking for ways to fix «pip: command not found» error message?
Pip, short for Preferred Installer Program, is a package management program written in Python and for Python. It can manage local packages, install/update them from Python Package Index (PyPI) and remove them at will. Users can also use pip to fetch packages from other package repositories as well, provided that they’re compatible with PEP 503.

Installing pip is easy, and should be easy, but still, there are common problems that happens to people from time to time, one of them is the annoying «pip: command not found» message, even though you’ve just installed pip.

This article is going to explain why «pip: command not found» sometimes pops up and provide a few possible fix to the error message.

The error message simply indicates that the system cannot find pip’s executable in places that it supposed to be.

The first thing you need to check is whether pip directory is included in PATH environment variable. Most operating systems look for executables and binaries in a specific set of places. The list of all those places is stored in an environment variable, often named PATH.

Another thing that can cause the problem is that the installed version of pip’s binary may not be named pip, hence, invalidate the command.

If you haven’t been able to identify the problem, the simplest way to fix is to reinstall pip. Please note that most of the time, reinstalling pip won’t cause any problem because all its code is contained in a single binary file, and the pip command simply call that binary. Having two identical executable binary in the same system won’t ever be a problem at all.

Reinstall pip using package managers

Python is open-source and popular, therefore, it’s no surprise that almost every major operating system include it in their standard distributions, or provide easy ways to install it.
In Debian/Ubuntu and its derivatives, you can run

sudo apt install python3-pip

In CentOS, RHEL and other distribution based on them, you have to add EPEL repository before actually install pip

yum install epel-release
yum install python-pip

Arch Linux uses pacman instead of apt and yum, so the command to install pip should be

pacman -S python-pip

On a Fedora system, one can install pip with the following command

dnf install python3-pip

Mac users have to run a brew command to get pip sorted out along with Python

brew install python

Most of the time, running one of the above command alone will fix the problem right away. You can verify it’s a successful installation with the command below.

pip --version

Reinstall pip using get-pip.py

If installing pip using package managers doesn’t work for you, try using get-pip.py, the official way to install pip, as per pip’s official documentation page.

get-pip.py is a bootstrapping script that enables users to install pip, setuptools, and wheel in Python environments that don’t already have them.

Let’s suppose you’re using Linux and already have wget installed on your system, you can run the following command to install pip. Please remember that in a few specific installation, you have to replace python with python3 to execute the right Python version.

wget https://bootstrap.pypa.io/get-pip.py
python get-pip.py

Reinstall pip using ensurepip

Recent versions of Python, specifically from Python 3.4, are bundled with a new ensurepip module as part of the standard packages. The ensurepip provides support for bootstrapping the pip installer into an existing Python installation or virtual environment.

ensurepip bootstrapping approach reflects the fact that pip is an independent project with its own release cycle, and the latest available stable version is bundled with maintenance and feature releases of the CPython reference interpreter.

You can simply run the following command to get pip installed. Please remember that in a few specific installation, you have to replace python with python3 to execute the right Python version.

python -m ensurepip

More information on ensurepip can be found at ensurepip — Bootstrapping the pip installer.

Double-check PATH environment variables

There are also a chance that pip path is not included in PATH environment variables. Most of the time, pip should be placed in /usr/local/bin in Linux and $HOME/homebrew/bin in MacOS.

You should add the following line to ~/.bash_profile to add /usr/local/bin to PATH every time the system starts and see if the problem goes away.

export PATH="/usr/local/bin:$PATH"

On MacOS, replace /usr/local/bin with $HOME/homebrew/bin so it would look like this:

export PATH="$HOME/homebrew/bin:$PATH"

Once you’re done the editing, restart the computer.

Add pip as an alias for pip3

A common scenario is that the installed pip executable is named pip3. Python 3 is not backwards-compatible, which means that programs that are written in Python 2 won’t run in Python 3 and vice versa. In order to keep the standard legacy applications, in specific versions, OSes keeps both Python 2 and Python 3. In that case, pip for Python 2 will be executed with pip and the one for Python3 is named pip3.

Run the following command to see if pip3 is actually installed.

pip3 --version

The system should response back a message indicates the pip version along with the Python version.

[email protected]:~$ pip3 --version
pip 20.0.2 from /usr/lib/python3/dist-packages/pip (python 3.8)

Now you have two options. You can use pip3 as it is or you can change the alias so that pip actually call pip3 executable. If you prefer the latter, run this command

alias pip=pip3

You would have to add the line above to ~/.bashrc or ~/.zprofile (in case you use ZSH) if you want the alias to persist through restarts.

Conclusion

We hope that the solutions above works for your case. If it didn’t, there may be something seriously wrong with your install, your best bet would be to reinstall the whole operating system from scratch or use another pip alternative such as conda.

You may like our other guides for Python to fix common error messages in Python, including «[Errno 32] Broken pipe» in Python, How to fix locale.Error: unsupported locale setting in Python or How to fix “unindent does not match any outer indentation level” indentation error in Python.