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Should I use pip or pip3? [duplicate]

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pip or pip3 to install packages for Python 3?
(10 answers)
Closed 2 years ago.
Eventually, every single time I install a new Linux distribution I do sudo apt-get install python3.
However, once installed I always get confused. python is Python 2.7 and python3 is Python 3.x. But also it appears that pip is for Python 2 and pip3 for Python 3. That said most tutorials I see on Internet always use the traditional pip install even though it is about Python 3.
How should I deal with this? Should I simply continue to put this annoying 3 every time I use Python (pip3, ipython3, python3...)? In most of my lectures I read that creating a symlink python->python3 is a bad practice. Is that correct?

Use python3 -m pip or python -m pip. That will use the correct pip for the python version you want. This method is mentioned in the pip documentation:
python -m pip executes pip using the Python interpreter you specified as python. So /usr/bin/python3.7 -m pip means you are executing pip for your interpreter located at /usr/bin/python3.7.
Symlinking python->python3 is a bad idea because some programs might rely on python being python 2. Though, I have seen some Dockerfiles symlink python->python3, like TensorFlow's CPU dockerfile (it's less of an issue in a Docker image). Coincidentally, that same Dockerfile uses the python3 -m pip install syntax that I recommend.

creating a symlink python->python3 is a bad practice. Is that correct?
Sometimes. Some OSs (looking at you, macOS) deeply rely on python pointing to a Python 2 interpreter for internal tools and tasks. Deleting the shipped Python 2 interpreter (or aliasing python to a Python 3 interpreter) will break stuff. How to uninstall Python 2.7 on a Mac OS X 10.6.4?

Whether the correct command for Python 3 is pip or pip3 or (say) gaschplutzga depends on a number of factors.
If you only have Python 3, and you have a command named pip, that's probably safe to use. Going forward, this will be the simple, obvious, safe answer in more and more places.
If you have both, and there is a command called pip3 installed on your system, probably that's the correct one to use.
More generally, you can go through your PATH and look for commands with suitable names. On Unix-like systems with a POSIX-compatible shell, try the commands command -V pip3 and command -V pip. (On Windows systems, maybe try where pip3 and where pip, or pray to whatever dark deity informed your choice of operating system.)
If you receive output like
/opt/random/nonstandard/whoa/pip
/usr/local/bin/pip
/usr/bin/pip
you can try each of these in turn with the full path and adding the --version option to have them identify themselves. When you specify the full path, you are bypassing the system's PATH mechanism entirely. For example,
/opt/random/nonstandard/whoa/pip --version
might identify itself as belonging to Python version 3.2.1. If that's the one you want, and it's at the top of your PATH, you can simply rely on the PATH to give you this version when you type just pip. If not, perhaps you can shuffle your PATH (but understand that this changes the resolution order for all commands in the directory whose position you change) or create a simple alias or wrapper which bypasses the PATH for this particular command in your personal account. On Unix-like systems with a POSIX-compatible shell, this might look like
alias pip=/opt/random/nonstandard/whoa/pip
(to persist this across sessions, you'd add this to your .profile or similar - for Bash, try .bash_profile if it exists; for Zsh, try .zshrc. The full scoop for each shell is more complicated than I can squeeze into these narrow parentheses); on Windows, you might be able to control this by setting the environment variable PY_PYTHON, but there's a huge can of worms behind that "might".
Some sites and OSes / distros have additional wrappers or conventions which introduce additional options; if you use a specific package manager, perhaps also study its documentation. (One common example is Anaconda, though I don't believe it affects the naming or location of pip specifically.)

Use virtual environments, then pip would be associated with the python used to create that virtual environment. Whether you use pip or pip3, it will be equivalent to python3 -m pip as mentioned in jakub's answer. Also, given that Python 2.7 is already EOL (which means you will most likely work with Python 3) and that pip install-ing things onto the system packages should be avoided, then a virtual environment would be helpful here.
For example, using pipenv:
$ pipenv --python=/usr/local/opt/python#3.8/bin/python3
$ pipenv shell
Launching subshell in virtual environment...
(TEMP) $ pip --version
pip 20.2.3 from /Users/me/.venvs/temp2-SbXvZiFd/lib/python3.8/site-packages/pip (python 3.8)
(TEMP) $ pip3 --version
pip 20.2.3 from /Users/me/.venvs/temp2-SbXvZiFd/lib/python3.8/site-packages/pip (python 3.8)
For example, using venv:
$ python3.8 -m venv .venv
$ source .venv/bin/activate
(.venv) $ pip --version
pip 20.2.3 from /Users/me/temp2/.venv/lib/python3.8/site-packages/pip (python 3.8)
(.venv) $ pip3 --version
pip 20.2.3 from /Users/me/temp2/.venv/lib/python3.8/site-packages/pip (python 3.8)
The virtual environment takes care of making sure pip or pip3 in this env refers to the pip from the correct Python version. You can then happily follow tutorials that still use pip install something (unless of course that tutorial refers to a Python 2.7 or a system-wide installation).

You can install pip through pip3 and this should resolve this issue.
$ pip --version
pip 19.0.3 from /usr/local/lib/python2.7/dist-packages/pip (python 2.7)
Notice that pip here is of Python 2.7 (in this example).
You can then force pip3 of Python 3.X to install pip under itself.
$ sudo pip3 install pip --upgrade
Installing collected packages: pip
Found existing installation: pip 8.1.1
Not uninstalling pip at /usr/lib/python3/dist-packages, outside environment /usr
Successfully installed pip-19.0.3
Once you check this again, it should reference Python 3.X so you don't have to deal with
what is what.
$ pip --version
pip 19.0.3 from /usr/local/lib/python3.5/dist-packages/pip (python 3.5)
I doubt you'll want to use Python 2 after this, but if you do happen to work with Python 2 code, you can create a virtual environment to access those commands again. Otherwise, you won't have to worry about the pip or pip3 distinction after this.
Not really a duplicate of this question, but this helped me suggest this answer: Can pip (python2) and pip3 (python3) coexist?

Pip is for python version less than 3. and pip3 is used when you want to install packages for python version 3 or higher.

Linux Mint Changing current version of Python

I have installed python 3.7 but still using and showing version of python 2.7 . I want to change it to 3.. I searched it but ı can't did it.

You should not change your syslink python to use python 3 because it is most likely that your system is using that syslink to python 2 for its own tasks and processes, if you change that, you may broke your system.
As Sammy said in a comment, you should use python3 to use that version.
On the pip side, it is probably that your python 3 does not have pip include (it should have it, but I have seen a lot of Python 3 without it). You can check if you have pip doing: python3 -m pip. The -m param is used to execute modules of python installed.
If you do not have pip installed, you can install it following this (which I recommend because always work): https://pip.pypa.io/en/stable/installing/
That is:
Download a script to install pip: curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
Execute the script in order to install pip (with sudo because you're going to modify your system): sudo python3 get-pip.py
Now you should have pip installed and doing python3 -m pip again should show you the help of pip.
If you have pip already installed and no pip3 command in your system, you can always create an alias to python3 -m pip with the name pip3 and problem solved. Also if you don't know or do not want to create alias or executables in the /usr/bin folder, you can always keep using python3 -m pip.
PS: It is highly recommended to use virtualenvs when developing with python. If you do not know what it is, here it is a link to the docs: https://virtualenv.pypa.io/en/latest/

Python3 does not find modules installed by pip3

I'm having problems with python3. For some reason that I cannot figure out, the modules available in python3 are not the same as the ones installed via pip3.
Running pip3 list in a Terminal returns:
DEPRECATION: The default format will switch to columns in the future. You can use --format=(legacy|columns) (or define a format=(legacy|columns) in your pip.conf under the [list] section) to disable this warning.
nltk (3.2.2)
numpy (1.12.0)
pandas (0.19.2)
pip (9.0.1)
python-dateutil (2.6.0)
pytz (2016.10)
setuptools (25.2.0)
six (1.10.0)
wheel (0.29.0)
Running this script to see what modules python3 has available returns:
['cycler==0.10.0', 'matplotlib==1.5.3', 'nltk==3.2.1', 'numpy==1.11.2', 'pip==9.0.1', 'pyparsing==2.1.10', 'python-dateutil==2.6.0', 'pytz==2016.7', 'setuptools==18.2', 'six==1.10.0']
These two are not the same and I can't tell why. nltk, for example, has an older version. pandas is missing.
I've installed python via homebrew and I'm running scripts via Textmate2. However, I have the same problem when I run code in terminal, via python3. Both pip3 and python3 are installed in /usr/local/bin/:
$ which python3 pip3
/usr/local/bin/python3
/usr/local/bin/pip3
And that's also the version python3 is using:
>>> import sys, os
>>> os.path.dirname(sys.executable)
'/usr/local/bin'
If someone could help me figure out why this is the case, and how I can fix it, I would very much appreciate the help.

Look at the first line of the pip3 script.
The first line (starting with #! should point to the same executable as the symbolic link for python 3:
> head -n 1 /usr/local/bin/pip
#!/usr/local/bin/python3.6
> ls -ld /usr/local/bin/python3
lrwxr-xr-x 1 root wheel 9 Dec 25 22:37 /usr/local/bin/python3# -> python3.6
If this is not the case, deinstall pip and install it again with the correct Python version.
EDIT:
If you really want to make sure that you're using the the right Python with pip, then call it as a module like this:
python3.7 -m pip list
If you get the error No module named pip, then pip is not installed for this version of python.

I ran to this problem in Windows. first of all I uninstall the package using cmd command pip3 uninstall moduleName.
Then based on python documentation I run command python -m pip install moduleName and my problem solved!
Here is the documentation: Installing Python Modules

Problems with installing matplotlib in python 3.6

I'm trying to teach myself python, and I feel out of my depth. To start, I am working on a mac which already comes with python 2.7 installed.
I installed python 3.6 recently and have been using it to teach myself the basics. I'd like to eventually learn how to produce mathematical plots in python, and I know I will need the matplotlib package to do that.
Following some advice online, I was told that python3 already comes with pip installed, which is what I thought I should use to install matplotlib. The advice said I should type the following into the mac terminal:
python3.6 -m pip install matplotlib
I typed this, and it seemed like the package was installing, but I ended up getting some sort of error code that said:
Command "python setup.py egg_info" failed with error code 1 in [folder].
I tried opening IDLE and typing "import matplotlib", but I got the error: "no module named matplotlib". I also tried typing "import matplotlib.pyplot as plt", but I got the same error.
Based on further research and this youtube video, I've decided to just install miniconda in order to have access to the matplotlib package.
The problem is, I'm not sure if I should somehow be uninstalling whatever was installed when I ran the code above to install matplotlib. I've actually run that line of code 3 or 4 times. Should I remove anything before installing miniconda? Also, I am running python 3.6, while miniconda is listed on the website as being for python 3.5. Does this mean it won't work for my version of python?

Running pip like that would install packages system-wide. I'm guessing it's failing because you're not running as root (i.e. the administrator user). But wait! Don't try again as root! Instead of installing packages, do it in a virtual environment. First create it:
virtualenv myenv
This creates a directory called myenv with a bunch of stuff in it (so make note of where you run this command). Whenever you want to use the virtual environment (like straight away!) you first need to activate it:
. myenv/bin/activate
Don't miss out that dot (followed by a space) at the beginning! As the other answer says, the first thing you should do in it is upgrade pip:
pip install --upgrade pip
Now you're ready install whatever else you like:
pip install matplotlib
One last note: The virtual environment is tied to a particular Python version. By default it uses the system's Python 2.7 installation, so to use a different one you need to specify it when you create the virtual environment, like this (if that Python version is installed system-wide):
virtualenv -p python3.5 myenv
Or like this (if that Python version is not installed system-wide):
virtualenv -p /path/to/my/installation/of/python3.5 myenv
While the virtual environment is activated, you don't need to specify the particular path/version of Python. Just run it like this:
python

I also encountered many problems during my installation.
It seems that version 2 of matplotlib is not compatible with Python version 3.
Finally, I succeeded by specifying version 3 of matplotlib as follows with the following command:
sudo apt-get install python3-matplotlib
Reference from the Matplotlib website:
https://matplotlib.org/users/installing.html#building-on-linux

Try upgrade setup tools
--upgrade setuptools
or
easy_install -U setuptools
or upgrade pip
pip install --upgrade pip

I ended up downloading anaconda and using the python interpreter that comes with it, as anaconda comes with matplotlib and many other python packages of interest.

the pip command typically is for the Python 2. use pip3 instead to install the libraries in the python 3.X path
This should work
pip3 install matplotlib

The solution that work for me in python 3.6 is the following
py -m pip install matplotlib

Matplotlib files are downloaded in ~/.local/lib/python3.6/site-packages/ and not in /usr/lib/python3.6/ .
Try the command:
sudo cp -r ~/.local/lib/python3.6/site-packages/* /usr/lib/python3.6/

Checking whether pip is installed?

I am using Python 2.7.12 and I want to check whether the pip is installed or not. For this, in command line of Python application I wrote pip list and pressed enter. However, I get an error like:
File"stdin",line 1
pip list
Syntax Error: invalid syntax
So, how can I solve this issue and get the list of modules as an output?
Thanks

Use command line and not python.
TLDR; On Windows, do:
python -m pip --version
OR
py -m pip --version
Details:
On Windows, ~> (open windows terminal) Start (or Windows Key) > type "cmd" Press Enter
You should see a screen that looks like this
To check to see if pip is installed.
python -m pip --version
if pip is installed, go ahead and use it. for example:
Z:\>python -m pip install selenium
if not installed, install pip, and you may need to add its path to the environment variables. (basic - windows)
add path to environment variables (basic+advanced)
if python is NOT installed you will get a result similar to the one below
Install python. add its path to environment variables.
UPDATE: for newer versions of python
replace "python" with py - see #gimmegimme's comment and link
https://packaging.python.org/guides/installing-using-pip-and-virtual-environments/

If you are on a linux machine running Python 2 you can run this commands:
1st make sure python 2 is installed:
python2 --version
2nd check to see if pip is installed:
pip --version
If you are running Python 3 you can run this command:
1st make sure python 3 is installed:
python3 --version
2nd check to see if pip3 is installed:
pip3 --version
If you do not have pip installed you can run these commands to install pip (it is recommended you install pip for Python 2 and Python 3):
Install pip for Python 2:
sudo apt install python-pip
Then verify if it is installed correctly:
pip --version
Install pip for Python 3:
sudo apt install python3-pip
Then verify if it is installed correctly:
pip3 --version
For more info see: https://itsfoss.com/install-pip-ubuntu/
UPDATE
I would like to mention a few things. When working with Django I learned that my Linux install requires me to use python 2.7, so switching my default python version for the python and pip command alias's to python 3 with alias python=python3 is not recommended. Therefore I use the python3 and pip3 commands when installing software like Django 3.0, which works better with Python 3. And I keep their alias's pointed towards whatever Python 3 version I want like so alias python3=python3.8.
Keep In Mind
When you are going to use your package in the future you will want to use the pip or pip3 command depending on which one you used to initially install the package. So for example if I wanted to change my change my Django package version I would use the pip3 command and not pip like so, pip3 install Django==3.0.11.
Notice
When running checking the packages version for python: $ python -m django --version and python3: $ python3 -m django --version, two different versions of django will show because I installed django v3.0.11 with pip3 and django v1.11.29 with pip.

$ which pip
or
$ pip -V
execute this command into your terminal. It should display the location of executable file eg. /usr/local/bin/pip and the second command will display the version if the pip is installed correctly.

pip list is a shell command. You should run it in your shell (bash/cmd), rather than invoke it from python interpreter.
pip does not provide a stable API. The only supported way of calling it is via subprocess, see docs and the code at the end of this answer.
However, if you want to just check if pip exists locally, without running it, and you are running Linux, I would suggest that you use bash's which command:
which pip
It should show you whether the command can be found in bash's PATH/aliases, and if it does, what does it actually execute.
If running pip is not an issue, you could just do:
python -m pip --version
If you really need to do it from a python script, you can always put the import statement into a try...except block:
try:
import pip
except ImportError:
print("Pip not present.")
Or check what's the output of a pip --version using subprocess module:
subprocess.check_call([sys.executable, '-m', 'pip', '--version'])

You need to run pip list in bash not in python.
pip list
DEPRECATION: Python 2.6 is no longer supported by the Python core team, please upgrade your Python. A future version of pip will drop support for Python 2.6
argparse (1.4.0)
Beaker (1.3.1)
cas (0.15)
cups (1.0)
cupshelpers (1.0)
decorator (3.0.1)
distribute (0.6.10)
---and other modules

In CMD, type:
pip freeze
And it will show you a list of all the modules installed including the version number.
Output:
aiohttp==1.1.4
async-timeout==1.1.0
cx-Freeze==4.3.4
Django==1.9.2
django-allauth==0.24.1
django-cors-headers==1.2.2
django-crispy-forms==1.6.0
django-robots==2.0
djangorestframework==3.3.2
easygui==0.98.0
future==0.16.0
httpie==0.9.6
matplotlib==1.5.3
multidict==2.1.2
numpy==1.11.2
oauthlib==1.0.3
pandas==0.19.1
pefile==2016.3.28
pygame==1.9.2b1
Pygments==2.1.3
PyInstaller==3.2
pyparsing==2.1.10
pypiwin32==219
PyQt5==5.7
pytz==2016.7
requests==2.9.1
requests-oauthlib==0.6
six==1.10.0
sympy==1.0
virtualenv==15.0.3
xlrd==1.0.0
yarl==0.7.0