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How do I check all pip packages for packages installed globally using sudo? [duplicate]

Is there a way in Python to list all installed packages and their versions?
I know I can go inside python/Lib/site-packages and see what files and directories exist, but I find this very awkward. What I'm looking for something that is similar to npm list i.e. npm-ls.

If you have pip install and you want to see what packages have been installed with your installer tools you can simply call this:
pip freeze
It will also include version numbers for the installed packages.
Update
pip has been updated to also produce the same output as pip freeze by calling:
pip list
Note
The output from pip list is formatted differently, so if you have some shell script that parses the output (maybe to grab the version number) of freeze and want to change your script to call list, you'll need to change your parsing code.

help('modules') should do it for you.
in IPython :
In [1]: import #import press-TAB
Display all 631 possibilities? (y or n)
ANSI audiodev markupbase
AptUrl audioop markupsafe
ArgImagePlugin avahi marshal
BaseHTTPServer axi math
Bastion base64 md5
BdfFontFile bdb mhlib
BmpImagePlugin binascii mimetools
BufrStubImagePlugin binhex mimetypes
CDDB bisect mimify
CDROM bonobo mmap
CGIHTTPServer brlapi mmkeys
Canvas bsddb modulefinder
CommandNotFound butterfly multifile
ConfigParser bz2 multiprocessing
ContainerIO cPickle musicbrainz2
Cookie cProfile mutagen
Crypto cStringIO mutex
CurImagePlugin cairo mx
DLFCN calendar netrc
DcxImagePlugin cdrom new
Dialog cgi nis
DiscID cgitb nntplib
DistUpgrade checkbox ntpath

If you want to get information about your installed python distributions and don't want to use your cmd console or terminal for it, but rather through python code, you can use the following code (tested with python 3.4):
import pip #needed to use the pip functions
for i in pip.get_installed_distributions(local_only=True):
print(i)
The pip.get_installed_distributions(local_only=True) function-call returns an iterable and because of the for-loop and the print function the elements contained in the iterable are printed out separated by new line characters (\n).
The result will (depending on your installed distributions) look something like this:
cycler 0.9.0
decorator 4.0.4
ipykernel 4.1.0
ipython 4.0.0
ipython-genutils 0.1.0
ipywidgets 4.0.3
Jinja2 2.8
jsonschema 2.5.1
jupyter 1.0.0
jupyter-client 4.1.1
#... and so on...

To run this in later versions of pip (tested on pip==10.0.1) use the following:
from pip._internal.operations.freeze import freeze
for requirement in freeze(local_only=True):
print(requirement)

My take:
#!/usr/bin/env python3
import pkg_resources
dists = [str(d).replace(" ","==") for d in pkg_resources.working_set]
for i in dists:
print(i)

from command line
python -c help('modules')
can be used to view all modules, and for specific modules
python -c help('os')
For Linux below will work
python -c "help('os')"

For easy_install (deprecated, Python <= v2.7, do not use this, use pip instead; use this only in old projects that still use easy_install)
You can try : Yolk
For install yolk, try:
easy_install yolk
Yolk is a Python tool for obtaining information about installed Python
packages and querying packages avilable on PyPI (Python Package
Index).
You can see which packages are active, non-active or in development
mode and show you which have newer versions available by querying
PyPI.

yes! you should be using pip as your python package manager ( http://pypi.python.org/pypi/pip )
with pip installed packages, you can do a
pip freeze
and it will list all installed packages. You should probably also be using virtualenv and virtualenvwrapper. When you start a new project, you can do
mkvirtualenv my_new_project
and then (inside that virtualenv), do
pip install all_your_stuff
This way, you can workon my_new_project and then pip freeze to see which packages are installed for that virtualenv/project.
for example:
➜ ~ mkvirtualenv yo_dude
New python executable in yo_dude/bin/python
Installing setuptools............done.
Installing pip...............done.
virtualenvwrapper.user_scripts creating /Users/aaylward/dev/virtualenvs/yo_dude/bin/predeactivate
virtualenvwrapper.user_scripts creating /Users/aaylward/dev/virtualenvs/yo_dude/bin/postdeactivate
virtualenvwrapper.user_scripts creating /Users/aaylward/dev/virtualenvs/yo_dude/bin/preactivate
virtualenvwrapper.user_scripts creating /Users/aaylward/dev/virtualenvs/yo_dude/bin/postactivate
virtualenvwrapper.user_scripts creating /Users/aaylward/dev/virtualenvs/yo_dude/bin/get_env_details
(yo_dude)➜ ~ pip install django
Downloading/unpacking django
Downloading Django-1.4.1.tar.gz (7.7Mb): 7.7Mb downloaded
Running setup.py egg_info for package django
Installing collected packages: django
Running setup.py install for django
changing mode of build/scripts-2.7/django-admin.py from 644 to 755
changing mode of /Users/aaylward/dev/virtualenvs/yo_dude/bin/django-admin.py to 755
Successfully installed django
Cleaning up...
(yo_dude)➜ ~ pip freeze
Django==1.4.1
wsgiref==0.1.2
(yo_dude)➜ ~
or if you have a python package with a requirements.pip file,
mkvirtualenv my_awesome_project
pip install -r requirements.pip
pip freeze
will do the trick

If you're using anaconda:
conda list
will do it! See: https://conda.io/docs/_downloads/conda-cheatsheet.pdf

Here's a way to do it using PYTHONPATH instead of the absolute path of your python libs dir:
for d in `echo "${PYTHONPATH}" | tr ':' '\n'`; do ls "${d}"; done
[ 10:43 Jonathan#MacBookPro-2 ~/xCode/Projects/Python for iOS/trunk/Python for iOS/Python for iOS ]$ for d in `echo "$PYTHONPATH" | tr ':' '\n'`; do ls "${d}"; done
libpython2.7.dylib pkgconfig python2.7
BaseHTTPServer.py _pyio.pyc cgitb.pyo doctest.pyo htmlentitydefs.pyc mimetools.pyc plat-mac runpy.py stringold.pyc traceback.pyo
BaseHTTPServer.pyc _pyio.pyo chunk.py dumbdbm.py htmlentitydefs.pyo mimetools.pyo platform.py runpy.pyc stringold.pyo tty.py
BaseHTTPServer.pyo _strptime.py chunk.pyc dumbdbm.pyc htmllib.py mimetypes.py platform.pyc runpy.pyo stringprep.py tty.pyc
Bastion.py _strptime.pyc chunk.pyo dumbdbm.pyo htmllib.pyc mimetypes.pyc platform.pyo sched.py stringprep.pyc tty.pyo
Bastion.pyc _strptime.pyo cmd.py
....

for using code, for example to check what modules in Hackerrank etc :
import os
os.system("pip list")

If this is needed to run from within python you can just invoke subprocess
from subprocess import PIPE, Popen
pip_process = Popen(["pip freeze"], stdout=PIPE,
stderr=PIPE, shell=True)
stdout, stderr = pip_process.communicate()
print(stdout.decode("utf-8"))

For Windows 10, I think this is what you are looking for a list of available installed Pythons. This is different from a list of packages as you can see below. Also, on Ubuntu 20.04, I think the command is Python3 -0 list.
Yes, this works similar to node version manager.
c:\Users\user\AppData\Local\Programs\Python>py -0 list
Python 0 not found!
Installed Pythons found by py Launcher for Windows
-3.10-64 *
-3.9-64
-3.7-64
-3.6-64
-2.7-64
Requested Python version (0) not installed, use -0 for available pythons
c:\Users\user\AppData\Local\Programs\Python>py -0p
Installed Pythons found by py Launcher for Windows
-3.10-64 C:\Python310\python.exe *
-3.9-64 C:\Users\user\AppData\Local\Programs\Python\Python39\python.exe
-3.7-64 C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\python.exe
-3.6-64 C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python36_64\python.exe
-2.7-64 C:\Python27amd64\python.exe
See: https://www.infoworld.com/article/3617292/how-to-use-pythons-py-launcher-for-windows.html
See Also: https://www.freecodecamp.org/news/manage-multiple-python-versions-and-virtual-environments-venv-pyenv-pyvenv-a29fb00c296f/
From the above link, "If you wish to use multiple versions of Python on a single machine, then pyenv is a commonly used tool to install and switch between versions. This is not to be confused with the previously mentioned depreciated pyvenv script. It does not come bundled with Python and must be installed separately." -- Note: This acts similar to Node Version Manager with versions of Node.js and NPM.
See Also: https://github.com/pyenv-win/pyenv-win#installation
Action: Open PowerShell and type the following web request. The link above offers other approaches as well, but this appears to be the easiest approach. The name of the runtime output file is not a name variant like 'pyenv-win' but actually 'pyenv', as originally expected.
PS C:\Users\user> Invoke-WebRequest -UseBasicParsing -Uri "https://raw.githubusercontent.com/pyenv-win/pyenv-win/master/pyenv-win/install-pyenv-win.ps1" -OutFile "./install-pyenv-win.ps1"; &"./install-pyenv-win.ps1"
pyenv-win 2.64.11 installed.
No updates available.
PS C:\Users\user>
Example Output for working with 'pyenv', Python's Version Manager.
C:\Users\user>pyenv --version
pyenv 2.64.11
C:\Users\name>pyenv
pyenv 2.64.11
Usage: pyenv <command> [<args>]
Some useful pyenv commands are:
commands List all available pyenv commands
duplicate Creates a duplicate python environment
local Set or show the local application-specific Python version
global Set or show the global Python version
shell Set or show the shell-specific Python version
install Install a Python version using python-build
uninstall Uninstall a specific Python version
update Update the cached version DB
rehash Rehash pyenv shims (run this after installing executables)
vname Show the current Python version
version Show the current Python version and its origin
version-name Show the current Python version
versions List all Python versions available to pyenv
exec Runs an executable by first preparing PATH so that the selected Python
which Display the full path to an executable
whence List all Python versions that contain the given executable
See `pyenv help <command>' for information on a specific command.
For full documentation, see: https://github.com/pyenv-win/pyenv-win#readme
C:\Users\name>pyenv commands
--version
commands
duplicate
exec
export
global
help
install
local
rehash
shell
shims
uninstall
update
version-name
version
versions
vname
whence
which
C:\Users\name>pyenv version
No global python version has been set yet. Please set the global version by typing:
pyenv global 3.7.2
C:\Users\user>pyenv local
no local version configured for this directory
C:\Users\user>pyenv global
no global version configured
C:\Users\user>pyenv local 3.9-64
pyenv specific python requisite didn't meet. Project is using different version of python.
Install python '3.9-64' by typing: 'pyenv install 3.9-64'
My Note: Version name from 'https://www.python.org/downloads/' is different to those provided by 'pyenv'. This version was already installed locally, but it is outside the control of this Python version manager, so it is not visible to the manager.
C:\Users\user>pyenv install 3.8.10-64
:: [Info] :: Mirror: https://www.python.org/ftp/python
pyenv-install: definition not found: local
My Note(s): This Python version is not part of the managed list although this version exists at 'https://www.python.org/downloads/'. So you must see the list provided by the manager. See all available versions with `pyenv install --list'.
C:\Users\user>pyenv install --list
Note: Review the list from this call and make your selection.
C:\Users\user>pyenv install 3.8.10
:: [Info] :: Mirror: https://www.python.org/ftp/python
:: [Downloading] :: 3.8.10 ...
:: [Downloading] :: From https://www.python.org/ftp/python/3.8.10/python-3.8.10-amd64-webinstall.exe
:: [Downloading] :: To C:\Users\user\.pyenv\pyenv-win\install_cache\python-3.8.10-amd64-webinstall.exe
:: [Installing] :: 3.8.10 ...
:: [Info] :: completed! 3.8.10
My Note(s): With this Python version manager, 'pyenv', following installation, it appears that one must designate the version as 'local' or 'global' after the installation which would follow the same paradigm as the Node.js Version Manager (NVM). Again, from what I can see, the Python version manager can only see what versions of Python the manager installs; and it can only uninstall a version it has installed with the Python version manager.
C:\Users\user>pyenv local 3.8.10
C:\Users\user>pyenv local
3.8.10
C:\Users\user>pyenv version
3.8.10 (set by C:\Users\user\.python-version)
C:\Users\user>pyenv versions
* 3.8.10 (set by C:\Users\user\.python-version)
C:\Users\user>pyenv vname
3.8.10
C:\Users\user>pyenv global
no global version configured
The following below is for working with packages.
See Also: https://www.freecodecamp.org/news/manage-multiple-python-versions-and-virtual-environments-venv-pyenv-pyvenv-a29fb00c296f/
From the above link, "When the environment is active, any packages can be installed to it via pip as normal. By default, the newly created environment will not include any packages already installed on the machine. As pip itself will not necessarily be installed on the machine. It is recommended to first upgrade pip to the latest version, using 'pip install --upgrade pip'." -- I performed the pip upgrade just before making these two calls to list the packages and their versions below.
c:\Users\user\AppData\Local\Programs\Python>pip list
Package Version
---------- -------
pip 22.1
setuptools 62.2.0
wheel 0.37.1
c:\Users\user\AppData\Local\Programs\Python>pip list --local
Package Version
---------- -------
pip 22.1
setuptools 62.2.0
wheel 0.37.1

Python in R - Error: could not find a Python environment for /usr/bin/python

I don't understand how R handles the Python environment and Python version and keep getting the error Error: could not find a Python environment for /usr/bin/python. I installed Miniconda and created a conda environment in the shell:
conda activate r-reticulate
Then, in R, I try to install keras (same problem with package tensorflow):
library(keras)
reticulate::use_condaenv()
install_keras(method = "conda", conda = reticulate::conda_binary())
... and get the following error:
Error: could not find a Python environment for /usr/bin/python
I tried to figure out what Python R should be using by
reticulate::py_config()
and get
python: /usr/bin/python
libpython: /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/config/libpython2.7.dylib
pythonhome: /System/Library/Frameworks/Python.framework/Versions/2.7:/System/Library/Frameworks/Python.framework/Versions/2.7
version: 2.7.16 (default, Jul 5 2020, 02:24:03) [GCC 4.2.1 Compatible Apple LLVM 11.0.3 (clang-1103.0.29.21) (-macos10.15-objc-
numpy: /Users/bestocke/Library/Python/2.7/lib/python/site-packages/numpy
numpy_version: 1.16.6
tensorflow: [NOT FOUND]
python versions found:
/usr/bin/python3
/usr/local/bin/python3
/usr/bin/python
I don't understand this. This seems to be using Python 2.7. When trying to figure out which Python is being used in the shell, I get:
> which python
/opt/miniconda3/envs/r-reticulate/bin/python
and
> ls -l /opt/miniconda3/envs/r-reticulate/bin/python
lrwxr-xr-x 1 username wheel 9 Aug 2 15:21 /opt/miniconda3/envs/r-reticulate/bin/python -> python3.6
Suggesting Python 3.6 should be used.
What am I getting wrong here?

Try to follow the guide at https://tensorflow.rstudio.com/installation/:
In your R-studio console :
install.packages("tensorflow")
library(tensorflow)
install_tensorflow()
If you have not installed Anaconda / Miniconda manually, then at step no. 3, a prompt will ask your permission to install Miniconda. If you already have conda installed, then :
Create new environment r-reticulate in conda : conda create -n r-reticulate
Install tensorflow from R-studio console with parameters : install_tensorflow(method = 'conda', envname = 'r-reticulate')
Load the reticulate package library(reticulate)
Activate the conda environment in R-studio use_condaenv('r-reticulate')
Load the tensorflow libray library(tensorflow)
Check if tensorflow is active tf$constant("Hellow Tensorflow")
References :
https://tensorflow.rstudio.com/installation/
https://rstudio.github.io/reticulate/

I installed using virtualenv, and I found that I have to specify the full path to the env by envname. It does not work by method="virtualenv", envname="r-reticulate"

I hope there is time to add information. I tried to do what Anugerah Erlaut said, but trying to install Keras GPU on R-studio Server, through WSL.
I knew the solution would work because I tried on another computer, but installing on Windows, and Keras CPU. After testing a while (and get frustrated), it seems that Rstudio does not have permissions to change the r-reticulate env.
So, I tried the solution running or "pure R", on bash command line, and it worked just fine!

PYTHONPATH is not read by IPython when installed via Homebrew

I installed IPython and Python 3 by using Homebrew on a clean macOS Catalina (virtual machine).
$ brew install ipython
As the ipython package is dependent on the python3 package, Homebrew installs ipython and python3 together.
$ brew info ipython
ipython: stable 7.13.0 (bottled), HEAD
Interactive computing in Python
https://ipython.org/
/usr/local/Cellar/ipython/7.13.0 (2,905 files, 21.8MB) *
Poured from bottle on 2020-04-15 at 18:48:22
From: https://github.com/Homebrew/homebrew-core/blob/master/Formula/ipython.rb
==> Dependencies
Required: python ✔, zeromq ✔
==> Options
--HEAD
Install HEAD version
==> Analytics
install: 11,543 (30 days), 33,591 (90 days), 98,995 (365 days)
install-on-request: 5,404 (30 days), 15,768 (90 days), 49,364 (365 days)
build-error: 0 (30 days)
I expected that both of these two commands read PYTHONPATH from my shell environment, because ipython works so when it is installed by pip3 install ipython.
However ipython and python3 installed by using Homebrew have different sys.path settings.
$ which ipython
/usr/local/bin/ipython
$ which python3
/usr/local/bin/python3
$ ipython
Python 3.7.7 (default, Mar 10 2020, 15:43:33)
Type 'copyright', 'credits' or 'license' for more information
IPython 7.13.0 -- An enhanced Interactive Python. Type '?' for help.
In [1]: import sys; sys.path
Out[1]:
['/usr/local/Cellar/ipython/7.13.0/libexec/bin',
'',
'/usr/local/Cellar/ipython/7.13.0/libexec/lib/python3.7/site-packages',
'/usr/local/Cellar/ipython/7.13.0/libexec/vendor/lib/python3.7/site-packages',
'/usr/local/Cellar/python/3.7.7/Frameworks/Python.framework/Versions/3.7/lib/python37.zip',
'/usr/local/Cellar/python/3.7.7/Frameworks/Python.framework/Versions/3.7/lib/python3.7',
'/usr/local/Cellar/python/3.7.7/Frameworks/Python.framework/Versions/3.7/lib/python3.7/lib-dynload',
'/usr/local/lib/python3.7/site-packages',
'/usr/local/Cellar/ipython/7.13.0/libexec/lib/python3.7/site-packages/IPython/extensions',
'/Users/oxon/.ipython']
$ python3
Python 3.7.7 (default, Mar 10 2020, 15:43:33)
[Clang 11.0.0 (clang-1100.0.33.17)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys; sys.path
['', '/Users/oxon/root-6.20.02/obj/lib', '/usr/local/Cellar/python/3.7.7/Frameworks/Python.framework/Versions/3.7/lib/python37.zip', '/usr/local/Cellar/python/3.7.7/Frameworks/Python.framework/Versions/3.7/lib/python3.7', '/usr/local/Cellar/python/3.7.7/Frameworks/Python.framework/Versions/3.7/lib/python3.7/lib-dynload', '/usr/local/lib/python3.7/site-packages']
Q1. Why are they different?
Q2. Is this an expected behavior?
Q3. Why IPython reads PYTHONPATH when it is installed by pip3 install ipython?

It comes down to the following line in the Homebrew recipe for ipython:
bin.env_script_all_files(libexec/"bin", :PYTHONPATH => ENV["PYTHONPATH"])
It creates the /usr/local/bin/ipython script that sets PYTHONPATH to a fixed value that is needed for IPython to work properly (since its modules are outside the default Python module directory) before calling the ipython executable:
#!/bin/bash
PYTHONPATH="/usr/local/Cellar/ipython/7.14.0/libexec/lib/python3.8/site-packages:/usr/local/Cellar/ipython/7.14.0/libexec/vendor/lib/python3.8/site-packages" exec "/usr/local/Cellar/ipython/7.14.0/libexec/bin/ipython" "$#"
It simply overrides your set value of PYTHONPATH. You may modify the script to read:
PYTHONPATH="$PYTHONPATH:/usr/local/Cellar/...
This will make it append to your PYTHONPATH instead of completely overriding it, but the file will be overwritten when the Homebrew package is updated or reinstalled. Therefore, it is advisable to instead put in the IPython startup directory ~/.ipython/profile_default/startup a script, say root.py that looks like:
import sys
sys.path.append('/Users/oxon/root-6.20.02/obj/lib')
When you install ipython using pip, its modules go into the default Python module directory, be it the system one or the user one or the one in the virtual environment, and it is not necessary to mess with PYTHONPATH for ipython to function correctly.
I'd say the answer to Q2 is therefore that it's probably a bug and you may submit an issue with Homebrew on GitHub, although I wouldn't hold my breath given how they treated the same issue with Jupyter.

Q1. Why are they (i.e., sys.path) different?
The way sys.path is populated is typically:
1) the current working directory, followed by 2) directories listed in your PYTHONPATH environment variable, followed by 3) installation-dependent default paths, which are controlled by the site module.
From https://docs.python.org/3/using/cmdline.html : PYTHONPATH: Augment the default search path for module files.
See also e.g.,
https://leemendelowitz.github.io/blog/how-does-python-find-packages.html
https://realpython.com/lessons/module-search-path/
https://learn.microsoft.com/en-us/visualstudio/python/search-paths?view=vs-2019
Therefore, each python installation may have its own sys.path.
In addition, sys.path does not need to be equal to PYTHONPATH
Check in each of the two (or three?) cases also the value and post back:
import os
print( 'PYTHONPATH = ', os.environ['PYTHONPATH'] )
For instance, I have spyder3 and python3.8 under Ubuntu 20.04. When started at the same CLI each has its own sys.path, both "derived" from the same PYTHONPATH.
Q2. Is this an expected behavior?
Yes.
Q3. Why IPython reads PYTHONPATH when it is installed by pip3 install ipython?
Please post the value of PYTHONPATH ($ echo $PYTHONPATH) prior to executing either of the pythons at the CLI. It is not evident that they are or are not reading its value.
Please post back if this helps finding the cause.

Eclipse with Python - having difficult with python version being picked up for egg file creation

I am using CentOS with Python 2.6 (/usr/bin/python2.6) but I installed Python 2.7.8 (/usr/local/lib/python2.7).
The egg files (on running a script on eclipse get created /usr/bin/python2.6/.. for the wrong version. I want it to get created in /usr/local/bin/python2.7/..
[code] [Desktop]$ which python
alias python='python2.7'
/usr/local/bin/python2.7 [/code]
The site-packages are present in /usr/local/lib/python2.7/site-packages
I have set the .bashrc file and PYTHONPATH to point to Python2.7 and checked output of "python -v" and "which python" which seems correct.
Is there something else that I could be missing? I always keep getting this error saying "no module named pkg_resources" found as a result of all this.
Thanks Lafada:
yum install python-setuptools
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:
/usr/local/lib/python2.7/site-packages/cStringIO.so: undefined symbol: PyCapsule_New
Please install a package which provides this module, or
verify that the module is installed correctly.
It's possible that the above module doesn't match the
current version of Python, which is:
2.6.6 (r266:84292, Jan 22 2014, 09:42:36)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-4)]
If you cannot solve this problem yourself, please go to
the yum faq at:
http://yum.baseurl.org/wiki/Faq
This clearly explains that there is some version issue/mix-up.. would you know about this?
Update:
I found something on stackoverflow which helped me on 2 packages but not the others. I see the following on my Python Interpreters.
[code]
/usr/local/lib/python2.7/site-packages/setuptools-5.4.1-py2.7.egg
/usr/local/lib/python2.7/site-packages/pip-1.5.6-py2.7.egg
/usr/lib/python2.6/site-packages/nose-1.3.3-py2.6.egg
/usr/lib/python2.6/site-packages/six-1.3.0-py2.6.egg
/usr/local/bin/python2.7
/usr/local/lib/python2.7/site-packag`enter code here`es
/usr/lib64/python2.6
/usr/lib64/python2.6/plat-linux2
/usr/lib64/python2.6/lib-dynload
/usr/lib64/python2.6/site-packages
/usr/lib64/python2.6/site-packages/gtk-2.0
/usr/lib64/python2.6/site-packages/webkit-1.0
/usr/lib/python2.6/site-packages
/usr/lib/python2.6/site-packages/setuptools-0.6c11-py2.6.egg-info
[/code]
I need the packages referencing py2.6 to refer to py2.7 and create egg files for 2.7.

You have to install python-setuptools
apt-get install python-setuptools
This will install pkg_resources module
Hi Lafada:
I have responded to your comment by editing my question.

Doing an "make altinstall" helped me and following http://toomuchdata.com/2014/02/16/how-to-install-python-on-centos/ was helpful.
For those modules that were still using py2.6, I re-installed them with pip by using "pip-2.7".

How to list all installed packages and their versions in Python?

Is there a way in Python to list all installed packages and their versions?
I know I can go inside python/Lib/site-packages and see what files and directories exist, but I find this very awkward. What I'm looking for something that is similar to npm list i.e. npm-ls.

If you have pip install and you want to see what packages have been installed with your installer tools you can simply call this:
pip freeze
It will also include version numbers for the installed packages.
Update
pip has been updated to also produce the same output as pip freeze by calling:
pip list
Note
The output from pip list is formatted differently, so if you have some shell script that parses the output (maybe to grab the version number) of freeze and want to change your script to call list, you'll need to change your parsing code.

help('modules') should do it for you.
in IPython :
In [1]: import #import press-TAB
Display all 631 possibilities? (y or n)
ANSI audiodev markupbase
AptUrl audioop markupsafe
ArgImagePlugin avahi marshal
BaseHTTPServer axi math
Bastion base64 md5
BdfFontFile bdb mhlib
BmpImagePlugin binascii mimetools
BufrStubImagePlugin binhex mimetypes
CDDB bisect mimify
CDROM bonobo mmap
CGIHTTPServer brlapi mmkeys
Canvas bsddb modulefinder
CommandNotFound butterfly multifile
ConfigParser bz2 multiprocessing
ContainerIO cPickle musicbrainz2
Cookie cProfile mutagen
Crypto cStringIO mutex
CurImagePlugin cairo mx
DLFCN calendar netrc
DcxImagePlugin cdrom new
Dialog cgi nis
DiscID cgitb nntplib
DistUpgrade checkbox ntpath

If you want to get information about your installed python distributions and don't want to use your cmd console or terminal for it, but rather through python code, you can use the following code (tested with python 3.4):
import pip #needed to use the pip functions
for i in pip.get_installed_distributions(local_only=True):
print(i)
The pip.get_installed_distributions(local_only=True) function-call returns an iterable and because of the for-loop and the print function the elements contained in the iterable are printed out separated by new line characters (\n).
The result will (depending on your installed distributions) look something like this:
cycler 0.9.0
decorator 4.0.4
ipykernel 4.1.0
ipython 4.0.0
ipython-genutils 0.1.0
ipywidgets 4.0.3
Jinja2 2.8
jsonschema 2.5.1
jupyter 1.0.0
jupyter-client 4.1.1
#... and so on...

To run this in later versions of pip (tested on pip==10.0.1) use the following:
from pip._internal.operations.freeze import freeze
for requirement in freeze(local_only=True):
print(requirement)

My take:
#!/usr/bin/env python3
import pkg_resources
dists = [str(d).replace(" ","==") for d in pkg_resources.working_set]
for i in dists:
print(i)

from command line
python -c help('modules')
can be used to view all modules, and for specific modules
python -c help('os')
For Linux below will work
python -c "help('os')"

For easy_install (deprecated, Python <= v2.7, do not use this, use pip instead; use this only in old projects that still use easy_install)
You can try : Yolk
For install yolk, try:
easy_install yolk
Yolk is a Python tool for obtaining information about installed Python
packages and querying packages avilable on PyPI (Python Package
Index).
You can see which packages are active, non-active or in development
mode and show you which have newer versions available by querying
PyPI.

yes! you should be using pip as your python package manager ( http://pypi.python.org/pypi/pip )
with pip installed packages, you can do a
pip freeze
and it will list all installed packages. You should probably also be using virtualenv and virtualenvwrapper. When you start a new project, you can do
mkvirtualenv my_new_project
and then (inside that virtualenv), do
pip install all_your_stuff
This way, you can workon my_new_project and then pip freeze to see which packages are installed for that virtualenv/project.
for example:
➜ ~ mkvirtualenv yo_dude
New python executable in yo_dude/bin/python
Installing setuptools............done.
Installing pip...............done.
virtualenvwrapper.user_scripts creating /Users/aaylward/dev/virtualenvs/yo_dude/bin/predeactivate
virtualenvwrapper.user_scripts creating /Users/aaylward/dev/virtualenvs/yo_dude/bin/postdeactivate
virtualenvwrapper.user_scripts creating /Users/aaylward/dev/virtualenvs/yo_dude/bin/preactivate
virtualenvwrapper.user_scripts creating /Users/aaylward/dev/virtualenvs/yo_dude/bin/postactivate
virtualenvwrapper.user_scripts creating /Users/aaylward/dev/virtualenvs/yo_dude/bin/get_env_details
(yo_dude)➜ ~ pip install django
Downloading/unpacking django
Downloading Django-1.4.1.tar.gz (7.7Mb): 7.7Mb downloaded
Running setup.py egg_info for package django
Installing collected packages: django
Running setup.py install for django
changing mode of build/scripts-2.7/django-admin.py from 644 to 755
changing mode of /Users/aaylward/dev/virtualenvs/yo_dude/bin/django-admin.py to 755
Successfully installed django
Cleaning up...
(yo_dude)➜ ~ pip freeze
Django==1.4.1
wsgiref==0.1.2
(yo_dude)➜ ~
or if you have a python package with a requirements.pip file,
mkvirtualenv my_awesome_project
pip install -r requirements.pip
pip freeze
will do the trick

If you're using anaconda:
conda list
will do it! See: https://conda.io/docs/_downloads/conda-cheatsheet.pdf

Here's a way to do it using PYTHONPATH instead of the absolute path of your python libs dir:
for d in `echo "${PYTHONPATH}" | tr ':' '\n'`; do ls "${d}"; done
[ 10:43 Jonathan#MacBookPro-2 ~/xCode/Projects/Python for iOS/trunk/Python for iOS/Python for iOS ]$ for d in `echo "$PYTHONPATH" | tr ':' '\n'`; do ls "${d}"; done
libpython2.7.dylib pkgconfig python2.7
BaseHTTPServer.py _pyio.pyc cgitb.pyo doctest.pyo htmlentitydefs.pyc mimetools.pyc plat-mac runpy.py stringold.pyc traceback.pyo
BaseHTTPServer.pyc _pyio.pyo chunk.py dumbdbm.py htmlentitydefs.pyo mimetools.pyo platform.py runpy.pyc stringold.pyo tty.py
BaseHTTPServer.pyo _strptime.py chunk.pyc dumbdbm.pyc htmllib.py mimetypes.py platform.pyc runpy.pyo stringprep.py tty.pyc
Bastion.py _strptime.pyc chunk.pyo dumbdbm.pyo htmllib.pyc mimetypes.pyc platform.pyo sched.py stringprep.pyc tty.pyo
Bastion.pyc _strptime.pyo cmd.py
....

for using code, for example to check what modules in Hackerrank etc :
import os
os.system("pip list")

If this is needed to run from within python you can just invoke subprocess
from subprocess import PIPE, Popen
pip_process = Popen(["pip freeze"], stdout=PIPE,
stderr=PIPE, shell=True)
stdout, stderr = pip_process.communicate()
print(stdout.decode("utf-8"))

For Windows 10, I think this is what you are looking for a list of available installed Pythons. This is different from a list of packages as you can see below. Also, on Ubuntu 20.04, I think the command is Python3 -0 list.
Yes, this works similar to node version manager.
c:\Users\user\AppData\Local\Programs\Python>py -0 list
Python 0 not found!
Installed Pythons found by py Launcher for Windows
-3.10-64 *
-3.9-64
-3.7-64
-3.6-64
-2.7-64
Requested Python version (0) not installed, use -0 for available pythons
c:\Users\user\AppData\Local\Programs\Python>py -0p
Installed Pythons found by py Launcher for Windows
-3.10-64 C:\Python310\python.exe *
-3.9-64 C:\Users\user\AppData\Local\Programs\Python\Python39\python.exe
-3.7-64 C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\python.exe
-3.6-64 C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python36_64\python.exe
-2.7-64 C:\Python27amd64\python.exe
See: https://www.infoworld.com/article/3617292/how-to-use-pythons-py-launcher-for-windows.html
See Also: https://www.freecodecamp.org/news/manage-multiple-python-versions-and-virtual-environments-venv-pyenv-pyvenv-a29fb00c296f/
From the above link, "If you wish to use multiple versions of Python on a single machine, then pyenv is a commonly used tool to install and switch between versions. This is not to be confused with the previously mentioned depreciated pyvenv script. It does not come bundled with Python and must be installed separately." -- Note: This acts similar to Node Version Manager with versions of Node.js and NPM.
See Also: https://github.com/pyenv-win/pyenv-win#installation
Action: Open PowerShell and type the following web request. The link above offers other approaches as well, but this appears to be the easiest approach. The name of the runtime output file is not a name variant like 'pyenv-win' but actually 'pyenv', as originally expected.
PS C:\Users\user> Invoke-WebRequest -UseBasicParsing -Uri "https://raw.githubusercontent.com/pyenv-win/pyenv-win/master/pyenv-win/install-pyenv-win.ps1" -OutFile "./install-pyenv-win.ps1"; &"./install-pyenv-win.ps1"
pyenv-win 2.64.11 installed.
No updates available.
PS C:\Users\user>
Example Output for working with 'pyenv', Python's Version Manager.
C:\Users\user>pyenv --version
pyenv 2.64.11
C:\Users\name>pyenv
pyenv 2.64.11
Usage: pyenv <command> [<args>]
Some useful pyenv commands are:
commands List all available pyenv commands
duplicate Creates a duplicate python environment
local Set or show the local application-specific Python version
global Set or show the global Python version
shell Set or show the shell-specific Python version
install Install a Python version using python-build
uninstall Uninstall a specific Python version
update Update the cached version DB
rehash Rehash pyenv shims (run this after installing executables)
vname Show the current Python version
version Show the current Python version and its origin
version-name Show the current Python version
versions List all Python versions available to pyenv
exec Runs an executable by first preparing PATH so that the selected Python
which Display the full path to an executable
whence List all Python versions that contain the given executable
See `pyenv help <command>' for information on a specific command.
For full documentation, see: https://github.com/pyenv-win/pyenv-win#readme
C:\Users\name>pyenv commands
--version
commands
duplicate
exec
export
global
help
install
local
rehash
shell
shims
uninstall
update
version-name
version
versions
vname
whence
which
C:\Users\name>pyenv version
No global python version has been set yet. Please set the global version by typing:
pyenv global 3.7.2
C:\Users\user>pyenv local
no local version configured for this directory
C:\Users\user>pyenv global
no global version configured
C:\Users\user>pyenv local 3.9-64
pyenv specific python requisite didn't meet. Project is using different version of python.
Install python '3.9-64' by typing: 'pyenv install 3.9-64'
My Note: Version name from 'https://www.python.org/downloads/' is different to those provided by 'pyenv'. This version was already installed locally, but it is outside the control of this Python version manager, so it is not visible to the manager.
C:\Users\user>pyenv install 3.8.10-64
:: [Info] :: Mirror: https://www.python.org/ftp/python
pyenv-install: definition not found: local
My Note(s): This Python version is not part of the managed list although this version exists at 'https://www.python.org/downloads/'. So you must see the list provided by the manager. See all available versions with `pyenv install --list'.
C:\Users\user>pyenv install --list
Note: Review the list from this call and make your selection.
C:\Users\user>pyenv install 3.8.10
:: [Info] :: Mirror: https://www.python.org/ftp/python
:: [Downloading] :: 3.8.10 ...
:: [Downloading] :: From https://www.python.org/ftp/python/3.8.10/python-3.8.10-amd64-webinstall.exe
:: [Downloading] :: To C:\Users\user\.pyenv\pyenv-win\install_cache\python-3.8.10-amd64-webinstall.exe
:: [Installing] :: 3.8.10 ...
:: [Info] :: completed! 3.8.10
My Note(s): With this Python version manager, 'pyenv', following installation, it appears that one must designate the version as 'local' or 'global' after the installation which would follow the same paradigm as the Node.js Version Manager (NVM). Again, from what I can see, the Python version manager can only see what versions of Python the manager installs; and it can only uninstall a version it has installed with the Python version manager.
C:\Users\user>pyenv local 3.8.10
C:\Users\user>pyenv local
3.8.10
C:\Users\user>pyenv version
3.8.10 (set by C:\Users\user\.python-version)
C:\Users\user>pyenv versions
* 3.8.10 (set by C:\Users\user\.python-version)
C:\Users\user>pyenv vname
3.8.10
C:\Users\user>pyenv global
no global version configured
The following below is for working with packages.
See Also: https://www.freecodecamp.org/news/manage-multiple-python-versions-and-virtual-environments-venv-pyenv-pyvenv-a29fb00c296f/
From the above link, "When the environment is active, any packages can be installed to it via pip as normal. By default, the newly created environment will not include any packages already installed on the machine. As pip itself will not necessarily be installed on the machine. It is recommended to first upgrade pip to the latest version, using 'pip install --upgrade pip'." -- I performed the pip upgrade just before making these two calls to list the packages and their versions below.
c:\Users\user\AppData\Local\Programs\Python>pip list
Package Version
---------- -------
pip 22.1
setuptools 62.2.0
wheel 0.37.1
c:\Users\user\AppData\Local\Programs\Python>pip list --local
Package Version
---------- -------
pip 22.1
setuptools 62.2.0
wheel 0.37.1