In case you are trying to install awscli and using cygwin and getting errors.
One of the errors that I encountered was
aws –version
> C:\windows-style-path-to-anaconda\python.exe: can’t open file > ‘cygdrive/c/cygdrive-style-path-to-anaconda/Scripts/aws’:
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The problem is that you have installed awscli in your other python installation, could be windows anaconda.
The installation has to be there in cygwin
The solution is to install python and pip inside cygwin: Use the below commands

pip uninstall awscli
wget rawgit.com/transcode-open/apt-cyg/master/apt-cyg
install apt-cyg /bin
apt-cyg install python
wget https://bootstrap.pypa.io/get-pip.py
python get-pip.py
pip install awscli

reference:
http://stackoverflow.com/questions/37149718/aws-cli-in-cygwin-how-to-clean-up-differences-in-windows-and-cygwin-style-path