第一本书：Getting Started with TensorFlow
source tensorflow/bin/activate
(source) deactivate
使用的是virtualenv来运行TensorFlow
1,安装virtualenv： sudo easy_install pip # If pip is not already installed
sudo pip install --upgrade virtualenv
2，Create a virtualenv environment by issuing a command of one of the following formats:
$ virtualenv --system-site-packages targetDirectory # for Python 2.7
$ virtualenv --system-site-packages -p python3 targetDirectory # for Python 3.n
where targetDirectory identifies the top of the virtualenv tree. Our instructions assume that targetDirectory is ~/tensorflow, but you may choose any directory.
3，Activate the virtualenv environment by issuing one of the following commands:
$ source ~/tensorflow/bin/activate # If using bash, sh, ksh, or zsh
$ source ~/tensorflow/bin/activate.csh # If using csh or tcsh
4，退出:(source) deactivate
tf.app.flags is a wrapper for the Python argparse module, which is commonly used to process command-line arguments, with some extra and specific functionality. tf.app.flags是一个Python argparse模块封装，这是常用的处理命令行参数，与一些额外的特定功能。
for instance, a Python command-line program with typical command-line arguments:
python distribute.py --job_name="ps" --task_index=0
The program distribute.py is passed the following: job_name="ps" task_index=0
This information is then extracted within the Python script, by using:
tf.app.flags.DEFINE_string("job_name", "", "name of job")
tf.app.flags.DEFINE_integer("task_index", 0, "Index of task")
tf.app.flags.flags是一个结构，包含所有参数解析从命令行输入的值。