writing pexpect like program in c++ on Linux

Is there any way of writing pexpect like small program which can launch a process and pass 开发者_C百科the password to that process? I don't want to install and use pexpect python library but want to know the logic behind it so that using linux system apis I can build something similar.

---

You could just use "expect". It is very light weight and is made to do what youre describing.

---

For very simple cases, empty is one option. It's a lightweight C program, and it can be used straight from a shell script and doesn't require Tcl.

For Debian/Ubuntu, the package is empty-expect.