scroll page by page or line by line using python curses

Question

Using python curses I am trying to write some text in to window. But when I reach end of window i get addstr() returned ERR

how to scroll the output page by

Answer 1

The problem is that your calls to screen.addstr have asked for a line number past the end of the screen. Taking into account the box which you have drawn on the screen, a better approach would be to create a new window just inside the box (using curses.newwin for example) and write the addstr calls within that window.

Your example does not compile as given. Here is a working example:

import curses
import logging
import subprocess
import sys

command = "ls -l /bin"
try:
    screen = curses.initscr()
    screen.immedok(True)
    curses.start_color()
    curses.init_pair(1, curses.COLOR_GREEN, curses.COLOR_BLACK)
    curses.init_pair(2, curses.COLOR_WHITE, curses.COLOR_BLACK)
    screen.bkgd(curses.color_pair(2))
    screen.border(0)
    boxed = curses.newwin(curses.LINES - 2, curses.COLS - 2, 1, 1)
    boxed.scrollok(1)

    p = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
    (output, err) = p.communicate()
    linenumber = 1
    for line in output.split("\n"):
        if linenumber <= 2:
            # First two lines are header, mark bold
            boxed.addstr(line, curses.color_pair(1)|curses.A_BOLD)
        else:
            boxed.addstr(line)
        boxed.addch("\n")
        linenumber += 1
        boxed.getch()

    screen.getch()
    curses.endwin()

except Exception, e:
    print "\n\033[1;91m[FAILED]\033[0m  Interrupt  ", e
    logging.error(e, exc_info=True)