了解一个环境变量
PYTHONSTARTUP
If this is the name of a readable file, the Python commands in that file are executed before the first prompt is displayed
in interactive mode. The file is executed in the same name space where interactive commands are executed so that objects
defined or imported in it can be used without qualification in the interactive session. You can also change the prompts
sys.ps1 and sys.ps2 in this file.
所以，我们可以指定一个文件为Python的命令行作配置！
可以在文件中写入任何想要的配置，当然可以进行tab自动补全：
1、创建～/.pythonconf，写入内容：
import readline, rlcompleter
readline.parse_and_bind("tab: complete")
2、在~/.bashrc中添加环境变量PYTHONSTARTUP:
export PYTHONSTARTUP=~/.pythonconf
source ~/.bashrc
就可以了，以后每次登陆之后，python在shell里面就能够自动补全了。