#! /usr/bin/env python """repeat <shell-command> This simple program repeatedly (at 1-second intervals) executes theshell command given on the command line and displays the output (or asmuch of it as fits on the screen).  It uses curses to paint each newoutput on top of the old output, so that if nothing changes, thescreen doesn't change.  This is handy to watch for changes in e.g. adirectory or process listing. To end, hit Control-C.""" # Author: Guido van Rossum # Disclaimer: there's a Linux program named 'watch' that does the same# thing.  Honestly, I didn't know of its existence when I wrote this! # To do: add features until it has the same functionality as watch(1);# then compare code size and development time. import osimport sysimport timeimport curses def main():    if not sys.argv[1:]:        print __doc__        sys.exit(0)    cmd = " ".join(sys.argv[1:])    p = os.popen(cmd, "r")    text = p.read()    sts = p.close()    if sts:        print >>sys.stderr, "Exit code:", sts        sys.exit(sts)    w = curses.initscr()    try:        while True:            w.erase()            try:                w.addstr(text)            except curses.error:                pass            w.refresh()            time.sleep(1)            p = os.popen(cmd, "r")            text = p.read()            sts = p.close()            if sts:                print >>sys.stderr, "Exit code:", sts                sys.exit(sts)    finally:        curses.endwin() main()