Question

#! /usr/bin/python

import curses
import curses.textpad as textpad

try:
    mainwindow = curses.initscr()
    textpad.Textbox(mainwindow).edit()
finally:
    curses.endwin()

the problem is that I type one character,but two characters display on screen.

Answer 1

Echoing is on by default. You need to call noecho for deactivating it.

#!/usr/bin/env python

import curses
import curses.textpad as textpad

try:
    mainwindow = curses.initscr()
    # Some curses-friendly terminal settings
    curses.cbreak(); mainwindow.keypad(1); curses.noecho()
    textpad.Textbox(mainwindow).edit()
finally:
    # Reverse curses-friendly terminal settings
    curses.nocbreak(); mainwindow.keypad(0); curses.echo()
    curses.endwin()

(the script has been tested on Python 2.7). I suggest you to have a look to the curses programming page.