Python script opening a bash prompt terminating the script

I want to write a chroot wrapper in python. The script will be copying some files, setting up some other stuff and then executing chroot and should land me in a chroot shell.

The tricky part is that I w开发者_JS百科ant no python processes running after I am in the chroot.

In other words, python should do the setup work, call chroot and terminate itself, leaving me in a chroot shell. When I exit the chroot, I should be in a directory where I was when I invoked the python script.

Is this possible?

My first thought would be to use one of the os.exec* functions. These will replace the Python process with the chroot process (or whatever you decide to run with exec*).

# ... do setup work
os.execl('/bin/chroot', '/bin/chroot', directory_name, shell_path)

(or something like that)

Alternatively, you can use a new thread for the popen command to avoid blocking the main code then pass the command results back.

import popen2
import time
result = '!' 
running = False

class pinger(threading.Thread):
    def __init__(self,num,who):
        self.num = num
        self.who = who
        threading.Thread.__init__(self)

    def run(self):
        global result
        cmd = "ping -n %s %s"%(self.num,self.who)
        fin,fout = popen2.popen4(cmd)
        while running:
            result = fin.readline()
            if not result:
                break
        fin.close()

if __name__ == "__main__":
    running = True
    ping = pinger(5,"127.0.0.1")
    ping.start()
    now = time.time()
    end = now+300
    old = result
    while True:
        if result != old:
            print result.strip()
            old = result
        if time.time() > end:
            print "Timeout"
            running = False
            break
        if not result:
            print "Finished"
            break