Popen in C programming

Question

How popen works in C ? And why I have to use FILE pointer to read output of popen, it is not a file.
And why popen in C is slower then os.popen in python. Does their is alternative function of popen which is much faster.

Can I make interactive shell using popen. If I make shell with popen then it will not be interactive, if I open a program with it then I will not be able to give input that program using my shell created by popen.

Answer 1

Martin Taylor
When user input something then his input saves in input buffer and then functions like getch() save input to variable and clear buffer.
Am I right ??

If I'm right then do you know how I can add something to input buffer without taking input from user but by myself ??

And do you have any idea, from where I can learn that buffering stuff ??