how to check which version of nltk, scikit learn installed?

import nltk is Python syntax, and as such won't work in a shell script.

To test the version of nltk and scikit_learn, you can write a Python script and run it. Such a script may look like

import nltkimport sklearnprint('The nltk version is {}.'.format(nltk.__version__))print('The scikit-learn version is {}.'.format(sklearn.__version__))# The nltk version is 3.0.0.# The scikit-learn version is 0.15.2.

Note that not all Python packages are guaranteed to have a __version__ attribute, so for some others it may fail, but for nltk and scikit-learn at least it will work.

Try this:

$ python -c "import nltk; print nltk.__version__"

In Windows® systems you can simply try

pip3 list | findstr scikitscikit-learn                  0.22.1

If you are on Anaconda try

conda list scikitscikit-learn              0.22.1           py37h6288b17_0

And this can be used to find out the version of any package you have installed. For example

pip3 list | findstr numpynumpy                         1.17.4numpydoc                      0.9.2

Or if you want to look for more than one package at a time

pip3 list | findstr "scikit numpy"numpy                         1.17.4numpydoc                      0.9.2scikit-learn                  0.22.1

Note the quote characters are required when searching for more than one word.

Take care.