/path/to/python2.{5,6} /path/to/pip install PackageName doesn’t work?

For this to work on any python version that doesn’t have pip already installed you need to download pip and do python*version* setup.py install. For example python3.3 setup.py install. This resolves the import error in the comments. (As suggested by @hbdgaf)

So apparently there are multiple versions of easy_install and pip. It seems to be a big mess. Anyway, this is what I did to install Django for Python 2.7 on Ubuntu 12.10:

$ sudo easy_install-2.7 pip
Searching for pip
Best match: pip 1.1
Adding pip 1.1 to easy-install.pth file
Installing pip-2.7 script to /usr/local/bin

Using /usr/lib/python2.7/dist-packages
Processing dependencies for pip
Finished processing dependencies for pip

$ sudo pip-2.7 install django
Downloading/unpacking django
  Downloading Django-1.5.1.tar.gz (8.0Mb): 8.0Mb downloaded
  Running setup.py egg_info for package django

    warning: no previously-included files matching '__pycache__' found under directory '*'
    warning: no previously-included files matching '*.py[co]' found under directory '*'
Installing collected packages: django
  Running setup.py install for django
    changing mode of build/scripts-2.7/django-admin.py from 644 to 755

    warning: no previously-included files matching '__pycache__' found under directory '*'
    warning: no previously-included files matching '*.py[co]' found under directory '*'
    changing mode of /usr/local/bin/django-admin.py to 755
Successfully installed django
Cleaning up...

$ python
Python 2.7.3 (default, Sep 26 2012, 21:51:14) 
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import django
>>> 

I had python 2.6 installed by default (Amazon EC2 AMI), but needed python2.7 plus some external packages for my application. Assuming you already installed python2.7 alongside with default python (2.6 in my case). Here is how to install pip and packages for non-default python2.7

Install pip for your python version:

curl -O https://bootstrap.pypa.io/get-pip.py
python27 get-pip.py

Use specific pip version to install packages:

pip2.7 install mysql-connector-python --allow-external mysql-connector-python

I ran into this issue myself recently and found that I wasn’t getting the right pip for Python 3, on my Linux system that also has Python 2.

First you must ensure that you have installed pip for your python version:

For Python 2:

sudo apt-get install python-pip

For Python 3:

sudo apt-get install python3-pip

Then to install packages for one version of Python or the other, simply use the following for Python 2:

pip install <package>

or for Python 3:

pip3 install <package>

On Windows, you can execute the pip module using a given Python version through the Python launcher, py.exe, if you chose to install it during Python 3 setup.

py -3 -m pip install packagename
py -2 -m pip install packagename

You can be even more specific and request an exact sub-version of Python:

py -3.6 -m pip install packagename

To get a list of all installed Python versions available through the launcher, run:

py --list

Alternatively, you can launch the desired Python executable directly:

C:/path/to/specific/python.exe -m pip install packagename

It worked for me in windows this way:

1. I changed the name of python files python.py and pythonw.exe to python3.py pythonw3.py

2. Then I just ran this command in the prompt:

   python3 -m pip install package

Other answers show how to use pip with both 2.X and 3.X Python, but does not show how to handle the case of multiple Python distributions (eg. original Python and Anaconda Python).

I have a total of 3 Python versions: original Python 2.7 and Python 3.5 and Anaconda Python 3.5.

Here is how I install a package into:

1. Original Python 3.5:

   /usr/bin/python3 -m pip install python-daemon
   

2. Original Python 2.7:

   /usr/bin/python -m pip install python-daemon
   

3. Anaconda Python 3.5:

   python3 -m pip install python-daemon
   

   or

   pip3 install python-daemon
   

   Simpler, as Anaconda overrides original Python binaries in user environment.

   Of course, installing in anaconda should be done with conda command, this is just an example.

Also, make sure that pip is installed for that specific python.You might need to manually install pip. This works in Ubuntu 16.04:

sudo apt-get install python-pip 

or

sudo apt-get install python3-pip

Context: Archlinux

Action:
Install python2-pip:
sudo pacman -S python2-pip

You now have pip2.7:
sudo pip2.7 install boto

Test (in my case I needed ‘boto’):
Run the following commands:

python2
import boto

Success: No error.

Exit: Ctrl+D

From here: https://docs.python.org/3/installing/

Here is how to install packages for various versions that are installed at the same time linux, mac, posix:

python2   -m pip install SomePackage  # default Python 2
python2.7 -m pip install SomePackage  # specifically Python 2.7
python3   -m pip install SomePackage  # default Python 3
python3.4 -m pip install SomePackage  # specifically Python 3.4
python3.5 -m pip install SomePackage  # specifically Python 3.5
python3.6 -m pip install SomePackage  # specifically Python 3.6

On Windows, use the py Python launcher in combination with the -m switch:

py -2   -m pip install SomePackage  # default Python 2
py -2.7 -m pip install SomePackage  # specifically Python 2.7
py -3   -m pip install SomePackage  # default Python 3
py -3.4 -m pip install SomePackage  # specifically Python 3.4

for example, if you set other versions (e.g. 3.5) as default and want to install pip for python 2.7:

1. download pip at https://pypi.python.org/pypi/pip (tar)
2. unzip tar file
3. cd to the file’s directory
4. sudo python2.7 setup.py install

pip is also a python package. So the easiest way to install modules to a specific python version would be below

 python2.7 /usr/bin/pip install foo

or

python2.7 -m pip install foo

Most of the answers here address the issue but I want to add something what was continually confusing me with regard to creating an alternate installation of python in the /usr/local on CentOS 7. When I installed there, it appeared like pip was working since I could use pip2.7 install and it would install modules. However, what I couldn’t figure out was why my newly installed version of python wasn’t seeing what I was installing.

It turns out in CentOS 7 that there is already a python2.7 and a pip2.7 in the /usr/bin folder. To install pip for your new python distribution, you need to specifically tell sudo to go to /usr/local/bin

sudo /usr/local/bin/python2.7 -m ensurepip

This should get pip2.7 installed in your /usr/local/bin folder along with your version of python. The trick is that when you want to install modules, you either need to modify the sudo $PATH variable to include /usr/local/bin or you need to execute

sudo /usr/local/bin/pip2.7 install <module>

if you want to install a new module. It took me forever to remember that sudo wasn’t immediately seeing /usr/local/bin.

You can go to for example C:Python2.7Scripts and then run cmd from that path. After that you can run pip2.7 install yourpackage…

That will install package for that version of Python.

On Linux, Mac OS X and other POSIX systems, use the versioned Python commands in combination with the -m switch to run the appropriate copy of pip:

python2.7 -m pip install SomePackage
python3.4 -m pip install SomePackage

(appropriately versioned pip commands may also be available)

On Windows, use the py Python launcher in combination with the -m switch:

py -2.7 -m pip install SomePackage  # specifically Python 2.7
py -3.4 -m pip install SomePackage  # specifically Python 3.4

if you get an error for py -3.4 then try:

pip install SomePackage

Here is my take on the problem. Works for Python3. The main features are:

• Each Python version is compiled from source
• All versions are installed locally
• Does not mangle your system’s default Python installation in any way
• Each Python version is isolated with virtualenv

Prerequisites: If you are using some bare-bones thin client with no extra turf installed, you should run this first (in ubuntu 18.04 at least, extra packages added for convenience):

sudo apt-get update
sudo apt-get install software-properties-common
sudo apt-add-repository universe
sudo apt-get update
sudo apt-get install -y build-essential cmake

sudo apt-get install -y zlib1g zlib1g-dev libsqlite3-dev 
openssl libssl-dev libffi-dev unzip pciutils net-tools 
libblas-dev gfortran libblas3 

The steps are as follows:

0. If you have several extra python versions installed in some other way, get rid of them, e.g., remove $HOME/.local/lib/python3.x, etc. (also the globally installed ones). Don’t touch your system’s default python3 version though.

1. Download source for different python versions under the following directory structure:

    $HOME/
        python_versions/ : download Python-*.tgz packages here and "tar xvf" them.  You'll get directories like this:
          Python-3.4.8/
          Python-3.6.5/
          Python-3.x.y/
          ...
   

2. At each "Python-3.x.y/" directory, do the following (do NOT use "sudo" in any of the steps!):

    mkdir root
    ./configure --prefix=$PWD/root 
    make -j 2
    make install
    virtualenv --no-site-packages -p root/bin/python3.x env
   

3. At "python_versions/" create files like this:

    env_python3x.bash:
   
    #!/bin/bash
    echo "type deactivate to exit"
    source $HOME/python_versions/Python-3.x.y/env/bin/activate
   

4. Now, anytime you wish to opt for python3.x, do

    source $HOME/python_versions/env_python3x.bash
   

to enter the virtualenv

6. While in the virtualenv, install your favorite python packages with

    pip install --upgrade package_name
   

7. To exit the virtualenv and python version just type "deactivate"

UPDATE

It seems that --no-site-packages is deprecated. There’s an easy fix for this: Once you have activated the virtualenv, just point the HOME env variable to somewhere else than your actual home directory, i.e.:

export HOME=some/where/else

A nice way to do this in general is:

• Create virtualenv
• Activate virtualenv
• If you want to "recycle" existing libraries to your virtualenv, softlink them from your existing install, i.e.
  ln -s $HOME/.local/lib/python3.6/site-packages/numpy $PWD/venv/lib/python3.6/site-packages/
• Do export PYTHONPATH=, export HOME=/some/other/dir

Now you should have custom-isolated virtualenv.

UPDATE 2 / SUDO

Wan’t to force sudo to use your virtualenv?

Defaults        secure_path="/home/USENAME/Python-3.x.y/env/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin"
Defaults        env_keep += "VIRTUAL_ENV"
Defaults        env_keep += "PYTHONPATH"

Now try "sudo python3 –version" and magic should happen

UPDATE 3 / DOCKER

Enable virtualenv inside your docker (of course, you have built it in your docker image):

ENV VIRTUAL_ENV=/home/USER/Python-3.x.y/env
ENV PYTHONPATH=
ENV PATH="$VIRTUAL_ENV/bin:$PATH"

This is probably the completely wrong thing to do (I’m a python noob), but I just went in and edited the pip file

#!/usr/bin/env python3 <-- I changed this line.

# -*- coding: utf-8 -*-
import re
import sys

from pip._internal import main

if __name__ == '__main__':
    sys.argv[0] = re.sub(r'(-script.pyw?|.exe)?$', '', sys.argv[0])
    sys.exit(main())

Installation of multiple versions of Python and respective Packages.

Python version on the same windows machine : 2.7 , 3.4 and 3.6

Installation of all 3 versions of Python :

• Installed the Python 2.7 , 3.4 and 3.6 with the below paths

PATH for all 3 versions of Python :

• Made sure the PATH variable ( in System Variables ) has below paths included – C:Python27;C:Python27Scripts;C:Python34;C:Python34Scripts;C:Python36;C:Python36Scripts;

Renaming the executables for versions :

• Changed the python executable name in C:Python36 and C:Python34 to python36 and python34 respectively.

Checked for the command prompt with all versions :

Installing the packages separately for each version

For windows specifically:
pathtopython.exe -m pip install PackageName works.

If you have multiple versions as well as multiple architectures (32 bit, 64 bit) you will need to add a -32 or -64 at the end of your version.

For windows, go to cmd and type py –list and it will produce the versions you have installed. The list will look like the following:

Installed Pythons found by py Launcher for Windows
 -3.7-64 *
 -3.7-32
 -3.6-32

The full command as an example will be:

py -3.6-32 -m pip install (package)

If you want to get more indepth, to install a specific version of a package on a specific version of python, use ==(version) after the package. As an example,

py -3.6-32 -m pip install opencv-python==4.1.0.25

for Blender:

/usr/bin $ python3.7 -m pip install irc

If you have both python3.6 and python3.7 installed and want to use pip with python3.7 by default, here’s what you should do:

First make sure you have pip installed for python3.7

python3.7 -m pip install -U pip

Now pip3.7 must be available, so we edit .bashrc

nano ~/.bashrc

adding the following line to it

alias pip=pip3.7

In order for the changes to take effect type in the shell:

source ~/.bashrc

Now if you type:

pip --version

you should get:

pip 20.1.1 from /usr/local/lib/python3.7/dist-packages/pip (python 3.7)

which means, if you use, for example:

pip install <package>

it would install the <package> for python3.7

Another possible way could be using conda and pip. Some time you probably want to use just one of those, but if you really need to set up a particular version of python I combine both.

1. I create a starting conda enviroment with the python I want. As in here https://docs.conda.io/projects/conda/en/latest/user-guide/tasks/manage-environments.html. Alternatively you could set up the whole enviroment just using conda.

   conda create -n myenv python=3.6.4

2. Then activate your enviroment with the python you like. This command could change depending on the OS.

   source activae myenv

3. Now you have your python active then you could continue using conda but if you need/want to use pip:

   python -m pip -r requirements.txt

Here you have a possible way.

You can use one of the following commands:

pip2 install SomePackage
pip3 install SomePackage

python2 -m pip install SomePackage  
python3 -m pip install SomePackage 

And of course, make sure that you have the correct version of pip installed

sudo apt-get install python-pip
sudo apt-get install python3-pip

I haven’t used these commands myself but, some answers above suggests using them to specify exactly the version of python you want to use

pip-2.7 install SomePackage
python-3.6 -m pip install SomePackage

For python 3 and Windows OS, I always use this syntax to install packages on different version:

First I always use Git Bash Command Prompt.

Here an example installing urllib package.

Default Python version:(The normal pip command)

pip install urllib3

For the other versions

py -3.8 -m pip install urllib3

py => for python

-3.8 => for the version (I’m using the 3.8.7 version) but if you’re using the 3.7.7 version it will be "-3.7"

-m : just because or for modify

pip install urllib3 : the normal pip command

To use multiple versions of pip, just type

pip{version} and run command

Example: for python 3.10

pip3.10

pip3.10 list

pip3.10

for Python 3.7

pip3.7

pip3.7 list

Some useful information for debugging this is the pip debug command. It shows the location of the python interpreter that it is attached to in the 1st line (after the warning).

$ pip debug
WARNING: This command is only meant for debugging. Do not use this with automation for parsing and getting these details, since the output and options of this command may change without notice.
pip version: pip 21.2.4 from /data/akshay/anaconda3/lib/python3.9/site-packages/pip (python 3.9)
sys.version: 3.9.12 (main, Apr  5 2022, 06:56:58)
sys.executable: /data/akshay/anaconda3/bin/python 

Simple and recent

On windows

1- Supposed that you have a different version of Python installed in your system. To check use the following command to check:

> py --list
 -3.10-64 *
 -3.7-64

2- Set your preferred default version:

• by setting the PY_PYTHON environment variable (e.g. PY_PYTHON=3.7).
• by settting the py.ini file usually located on C:Users<your user name>AppDataLocal if not create one. For example, setting PY_PYTHON=3 and PY_PYTHON3=3.7 environment variables are equivalent to the INI file containing:

[defaults]
python=3
python3=3.7

3- check by typing again py --list:

> py --list
 -3.10-64 
 -3.7-64 *

4- If you would like to run virtual environment with spesific version of python and pip see this post.

On Linux (Ubuntu)

An easy approach for managing different python versions on Linux is update-alternatives command. This command giving us the ability to switch between many versions of the same software easily.

• command format:update-alternatives --install link name path priority, the name is the generic name for the master link, the link is the name of its symlink, the path is the alternative being introduced for the master link, and priority is the priority of the alternatives group.
• Usage: Suppose you installed two versions of python (python3.10 , python3.7). Now by running this command you will link the command name (python3) to different versions of python and assign a priority number. A higher priority number means a higher priority.

$ update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.7 1
$ update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.10 2

• List installed versions of python with this command:

$ update-alternatives --list python3
/usr/bin/python3.7
/usr/bin/python3.10

• Switching between versions: Just manually select the priority number of the desired python version after running following command.

$ update-alternatives --config python3

There are 2 choices for the alternative python3 (providing /usr/bin/python3).

  Selection    Path                      Priority   Status
------------------------------------------------------------
  0            /usr/bin/python3.10   2         auto mode
* 1            /usr/bin/python3.7   1         manual mode
  2            /usr/bin/python3.10   2         manual mode

Press <enter> to keep the current choice[*], or type selection number: 2

Updating PIP and installing Packages while using specific location of pip:

I was getting an intermittent error "Access Denied" when using the simple comand line pip install <library> on some lab machines that were using pip from a c:users... folder instead of the c:Program FilesPython folder for all users.
Thanks to MultiplyByZer0 answer above I was able to implement a solution that specified the path to python and then run pip.

Here is the powershell script I use to force pip update and then install python libraries:

$fullPath = "C:Program FilesPython38"
$thisApp = "python.exe"
$arguments = "-m pip install --upgrade pip"
$appPath = join-path $fullPath $thisApp
Start-Process $appPath $arguments  -Verb RunAs -Wait
$packages = @(  "pylint"
                "pillow"
                "pygame"
                "matplotlib"
                "pandas"
                "godirect")
foreach ($package in $packages)
   {
       Write-Host "Installing python Package" $package -ForegroundColor Yellow
       $arguments = "-m pip install $package"
       Start-Process $appPath $arguments  -Verb RunAs -Wait
   }