conda info --envs

source activate [envname]

https://zhuanlan.zhihu.com/p/22678445

http://www.jianshu.com/p/d2e15200ee9b

This worked for me on Ubuntu 16.04:

python2 -m pip install ipykernel

python2 -m ipykernel install --user

python3 -m pip install ipykernel

python3 -m ipykernel install --user

Reference to the documentation: link