由于在ubuntu环境下，将python做与python3.6做了软链接（ln -s python python3.6），并且pip也被我做了软链接，所以导致用pip安装virtualenvwrapper之后，在source启动virtualenvwrapper.sh时以及workon 虚拟环境时总是报错：
1 ./virtualenvwrapper.sh: line 230: : command not found 2 virtualenvwrapper.sh: There was a problem running the initialization hooks. 3 4 If Python could not import the module virtualenvwrapper.hook_loader, 5 check that virtualenvwrapper has been installed for 6 VIRTUALENVWRAPPER_PYTHON= and that PATH is 7 set properly.
这是根据提示230行的语句：
1 "$VIRTUALENVWRAPPER_PYTHON" -m 'virtualenvwrapper.hook_loader'
结合错误信息与提示找到的语句，猜测应该是VIRTUALENVWRAPPER_PYTHON这里有问题，然后在virtualenvwrapper.sh文件中查找VIRTUALENVWRAPPER_PYTHON，发现了关键点：
1 # Locate the global Python where virtualenvwrapper is installed. 2 if [ "${VIRTUALENVWRAPPER_PYTHON:-}" = "" ] 3 then 4 VIRTUALENVWRAPPER_PYTHON="$(command which python3)" # 原本是写的which python，这里贴出来的是我修改为python3后的。 5 fi
VIRTUALENVWRAPPER_PYTHON是用来(Locate the global Python where virtualenvwrapper is installed.)定位哪个python下面安装了virtualenvwrapper的。原本指定的位置是python，也就是2.7版本的。鉴于之前我使用python3.6安装的，所以此处要改成python3。然后这个错误就消失了。
使用virtualenvwrapper的好处是不用每次使用source /xxx/虚拟环境/bin/activate来启动虚拟环境了，在~/.bashrc配置一下，日后开启虚拟环境直接可以用workon命令即可，具体操作步骤，前提是你已经安装了python-virtualenv了：
# Setup: # 1. Create a directory to hold the virtual environments. # (mkdir $HOME/.virtualenvs). # 2. Add a line like "export WORKON_HOME=$HOME/.virtualenvs" # to your .bashrc. # 3. Add a line like "source /path/to/this/file/virtualenvwrapper.sh" # to your .bashrc. # 4. Run: source ~/.bashrc # 5. Run: workon # 6. A list of environments, empty, is printed. # 7. Run: mkvirtualenv temp # 8. Run: workon # 9. This time, the "temp" environment is included. # 10. Run: workon temp # 11. The virtual environment is activated.