(tensorflow)$ pip install --upgrade pip # for Python 2.7
(tensorflow)$ pip3 install --upgrade pip # for Python 3.n
(tensorflow)$ pip install --upgrade tensorflow # for Python 2.7
(tensorflow)$ pip3 install --upgrade tensorflow # for Python 3.n
(tensorflow)$ pip install --upgrade tensorflow-gpu # for Python 2.7 and GPU
(tensorflow)$ pip3 install --upgrade tensorflow-gpu # for Python 3.n and GPU
(tensorflow)$ pip install --upgrade tensorflow-gpu==1.4.1 # for a specific version
Details on install tensorflow.