linux下运行pip -V命令报错

安装完pip后运行pip -V
出现如下报错

File "/usr/bin/pip", line 7, in <module>
    from pip._internal.main import main
  File "/usr/lib/python2.6/site-packages/pip/_internal/main.py", line 13, in <module>
    from pip._internal.cli.autocompletion import autocomplete
  File "/usr/lib/python2.6/site-packages/pip/_internal/cli/autocompletion.py", line 11, in <module>
    from pip._internal.cli.main_parser import create_main_parser
  File "/usr/lib/python2.6/site-packages/pip/_internal/cli/main_parser.py", line 7, in <module>
    from pip._internal.cli import cmdoptions
  File "/usr/lib/python2.6/site-packages/pip/_internal/cli/cmdoptions.py", line 105
    binary_only = FormatControl(set(), {':all:'})
                                               ^
SyntaxError: invalid syntax

后来发现无论是运行pip的任何命令，都出现同样的报错，网上初步搜索答案是需要配置环境变量
运行which命令
[root@localhost src]# which python
/usr/bin/python
之后运行
vi /etc/profile
在profile文件最后一行添加如下
export PATH=”$PATH:/usr/bin/python″
之后
source /etc/profile
再次测试pip -V
任然报同样的错误，
没办法，求解