terminal-emulator.py

import os, pty, subprocess, time

# Ask the OS to create a new "pseudoterminal pair"
# The shell is going to have the "tty" end and the terminal emulator is going to have the 
# "pseudoterminal master" ("ptmx") end

ptmx, tty = pty.openpty()
shell_process = subprocess.Popen(
    ["/bin/bash"], stdin=tty, stdout=tty, stderr=tty, text=False, close_fds=True
)

# send a command to the shell
# (in real life you would wait for the user to type things in and write what they typed in)
os.write(ptmx, b"echo 'Hello from shell'\n")

# wait a bit for the command to execute
time.sleep(0.5)

# read the response and print it out
# (in real life you would implement a GUI and display this to the screen)
response = os.read(ptmx, 1024)
print(response.decode("utf-8"))