Introduction - If you have any usage issues, please Google them yourself
1, this source code as I wrote, non-GNU source code, do not let that mislead you, put this to only exchange
2, this source code is not complete, the shell s many features are not implemented, but to achieve some of the major functions
3, the following functions:
a, enter the command and run
b, if and while the deeply nested
c, the environment variable, and the shell itself variable
d, pipes and redirection.
4, due to capacity issues, the program may have errors and welcome expert guidance