如何安装PIL？
>pip install PIL
Downloading/unpacking PIL
Could not find any downloads that satisfy the requirement PIL
Some externally hosted files were ignored (use --allow-external PIL to allow).
Cleaning up...
No distributions at all found for PIL
Storing debug log for failure in /root/.pip/pip.log
>pip uninstall PIL
Can't uninstall 'PIL'. No files were found to uninstall.