I have a CentOs system with both Python 2.7 and Python 3.4 installed. I do not have information regarding how these were installed.
However, this is the response when the following commands are issued:
whereis /usr/bin/python3
python3:
/usr/bin/python3.4
/usr/bin/python3.4m
/usr/lib/python3.4
/usr/lib64/python3.4
/usr/include/python3.4m
whereis /usr/bin/python2.7
python2:
/usr/bin/python2.7
/usr/bin/python2
/usr/lib/python2.7
/usr/lib64/python2.7
/usr/include/python2.7
/usr/share/man/man1/python2.1.gz
I am uncertain how to use PIP in this setup. Python documentation for PIP mentions it assumes that your environment is virtual.
If I want to install a module in python3.4 using PIP, what are the steps?
1. sudo as root?
2. set environmental variables?
3. etc...
Installing a Python package is fairly straightforward, you need to first verify that it's not already packaged by your distro, in your case:
yum search <module_name>
Those packages are generally named like: python-<module_name> for a Python 2 module and python3-<module_name> for a Python 3 module.
If it doesn't exist as a package, you can then rely on PyPI:
python3 -m pip install <module_name> --user
From my answer here
Let's break the this command in two parts:
python -m: Allows modules to be located using the Python module namespace for execution as scripts. The motivating examples were standard library modules such as pdb and profile. See PEP 338
--user : By default Python installs Python packages to system directories which requires root privileges, to avoid using sudo pip install (which is not recommended by the way) use this flag to make pip install packages in your home directory instead, which doesn't require any special privileges.
As a side note, if you have multiple versions of Python installed, keeping track of which Python version version pip is bound to can be a PITA, hence python -m, in this case you're sure that it's the pip bound to the Python called which will be executed.
While the previous method works (kinda), it's advised to use virtual environments because many Linux distributions (including CentOs) rely on some Python modules and you don't want to modify them unless you know what you are doing or you absolutely want to break your System.
Additionally, if you only want to "Install and Run Python Applications in Isolated Environments", you can check out pipx.
I always use pip3 when I want to directly refer to python3.
If I want to install a module in python3.4 using PIP, what are the steps? 1. sudo as root? 2. set environmental variables? 3. etc...
just this
sudo apt install python3-pip
pip3 install xyz
Related
I tried to install a certain python module that required python 3.6 minimum to work properly so I checked my version using python --version which gave me the output of Python 2.7.17 and then used python3 --version giving me Python 3.6.9. Now, I know for a fact that i have Python 3.8 installed because I ran apt install python3.8 just before checking the version.
If someone wants to know what my system is running; I am currently running Elementary OS 5.1.7 Hera.
EDIT:
(IDK what term to use, I want to say I am done going through answers, and I liked none.)
After a while of whacking my brain, I decided not to uninstall the 3.6 version as It may have version specific modules which if removed may cause other installed programs to break.
Since I just use Linux for my college-work, It wont matter if more than one versions are installed anyway.
Sorry for any mistakes I may have made, I was never good at this kind of things.
Use conda to install and manage different versions of Python (or lots of other software, for that matter). Install different Python versions in separate conda environments. For example:
Find what python versions are available:
conda search python
Output (as of the time of writing, in the future I expect that the latest Python versions will be higher):
Loading channels: done
# Name Version Build Channel
python 1.0.1 0 conda-forge
python 1.2 0 conda-forge
...
python 3.9.0 h88f2d9e_1 pkgs/main
python 3.9.0 ha017127_4_cpython conda-forge
Install the Python versions you need in separate environments. Here, install Python 3.9.0 in environment named python39:
conda create --name python39 python=3.9.0
Switching environments is easy:
conda activate python39
# python is now 3.9.0
conda deactivate
# back to the default python
or (deprecated now):
source activate python39
source deactivate
SEE ALSO:
conda docs: Managing environments
This question is more appropriate for Unix & Linux.
Python installations (more generally, versioned installations of software) co-exist on linux using version numbers. You can likely run Python 3.8 using the python3.8 command (or else, locate where you installed it and run from there / add the location to the PATH environment variable to run directly).
Likewise, for each python version you can install its own package manager (e.g. install pip3.8 by python3.8 -m pip install pip) and use it to install packages for that python version. (As different projects require different sets of packages, the general practice is to create a "virtual environment", i.e. a separate copy of the needed version of python, pip and their package installation folders for each project, and install the required packages there - for more information see e.g. this excellent answer).
Regarding the command python3 (usually /usr/bin/python3) is just a symbolic link, you can replace it with the version you like (as long as it remains compatible with what the system expects - i.e. python3 of version no less than your built-in python3/python3-minimal, otherwise you will probably break something), e.g. assuming which python3 gives you /usr/bin/python3, you can
sudo rm /usr/bin/python3 #remove existing link
sudo ln /usr/bin/python3.8 /usr/bin/python3 # create a new link to the version of your choice
(although a better alternative could be instead aliasing it alias python3='/usr/bin/python3.8' and adding this to ~/.bashrc).
Whatever you do, do not uninstall python3-minimal as it is - at least, on Ubuntu - required by the system and uninstalling or changing it will likely break the system.
If I try to use autopep8 in cygwin (64bit, WIndows10) i get the message "command not found".
$ autopep8
-bash: autopep8: command not found
I tried pip install autopep8 but pip is also not found, only pip2 and pip3.
If I use python -m pip install autopep8 it works so I can call
python -m autopep8
but I want to run a script where just autopep8 is called:
if ! type -p autopep8 >/dev/null; then
echo "autopep8 not found" >&2
autopep8() {
Any ideas how to solve this?
First, you must install PyPi packages to the correct Python installation, and second, you must install the same package to every Python installation in which you want to use it.
Now, a special note about installing Python on Cygwin. You have a choice of several Python versions to install, and scores of packages for use with each of those versions. Avoid Python version 2 unless you have a clearly define reason, as it is post End-of-Life. Instead, install one of the versions of Python 3. As of today, version 3.6 and 3.7 have the more complete sets of optional packages. Version 3.8 beta 4 is available.
For a my install of Python 3.8, I used the Cygwin setup app to install these packages: Python38 (Py3K language interpreter), Python38-pip (Python package installation tool), Python38-setuptools (Python package management tool), Python38-virtualenv (Creates isolated Python environments), and Python38-wheel (Python package format module). To write X11 GUI apps, add Python38-tkinter (Py3K Tkinter GUI module). To install binary packages, add Python38-devel (Py3K language interpreter).
You will be able to install pure Python packages from PyPI. To install binary packages you will also need to have the GNU compiler tool chain installed, and you will need to handle dependencies with other Cygwin packages on your own.
The Python 3.6 and 3.7 installations have addition packages which, in many cases, contain binary packages with the above mentioned dependencies already resolved, or have some useful customizations for the Cygwin environment.
Cygwin has both Python 2 and Python 3. As of today, after installation, you execute Python 2 by python and Python 3 by python3. Be careful which Python you execute as you may get a windows version of Python, if installed, and in your path. which python will always tell where the executable lives, and python -V, etc., will tell you which version you are running. Generally, you want to run a Cygwin version of Python from the bash prompt and Windows versions of Python only from the command prompt or windows GUI.
The safest way to use pip is to use the module version for the Python executable you have chosen, i.e., python -m pip, etc. This avoids having to also remember to use pip with Python and pip3 with Python3.
I am having trouble with my current python, so I wanted to uninstall my python and install the latest version. I installed with homebrew, so I uninstalled it with homebrew and reinstalled python 3.8.1 with the installer from the official site. Python3.8 was installed, but my python3 was not upgraded.
~ which python3
/usr/bin/python3
~ python3 --version
Python 3.7.3
I know I'm not supposed to(and I can't) manually delete things inside /usr/bin. What am I supposed to do?
When you installed Python with homebrew it told you this:
Unversioned symlinks python, python-config, pip etc. pointing to
python3, python3-config, pip3 etc., respectively, have been
installed into /usr/local/opt/python/libexec/bin
If you need a reminder, post install, you will get the same message if you run:
brew info python
It says "unversioned links are in /usr/local/opt/python/libexec/bin". That means, if you want to run Python without specifying the version, i.e. if you want to type this:
python
and this:
pip
to start Python 3 and its corresponding pip, you need to make sure your PATH has /usr/local/opt/python/libexec/bin at the start, i.e.
export PATH=/usr/local/opt/python/libexec/bin:$PATH
I could not uninstall the python3 in /usr/bin but found a workaround to give the python3 in /usr/loca/bin precedence by setting the PATH env variable as PATH=/usr/local/bin:$PATH. This gives binaries in /usr/local/bin precedence. Not a full fledged solution, but got me moving.
my computer have python3.4, python3.5, python3.6, python3.7, but now i want to use python virtualenv to create a env , but it show path not found?
The image in here:
You need to provide the full path to Python, for example:
virtualenv.exe -p C:\Python37\python.exe
For git-bash the command should be slightly different:
virtualenv.exe -p /c/Python37/python.exe
First of all having multiple versions of Python is not advised especially if you cant manage them. The issue you are getting stems from the installation of the Virtualenv package. You need to use the python version that has Virtualenv in the site-packages. Examine all the site packages for the 3 versions then use the one that has virtualenv alternatively you can uninstall all the 3 versions and reinstall one I'd advise on Python 3.6 then install virtualenv via pip and try again.
I'm using Fedora 21. Installed the python3-tkinter package using yum install python3-tkinter. The package gets stored in the /usr/lib64/python3.4 directory. Is there a way to use pip to install tkinter?
Have a virtualenv setup with python3. When I try to run my program within that virtualenv I get:
ImportError: No module named 'tkinter'.
Does it make sense to copy the package directories from /usr/lib64/python3.4 to the site_packages folder associated with the virtualenv?
I was using python 3.3.2 interpreter. Turns out the default packages installed when running the command yum install python3-tkinter are set to work with python 3.4.1 interpreter. Configuring my virtualenv to use the python 3.4.1 interpreter proved to be the solution as the python interpreter was then able to find the required libraries in it's path.