Python fork exec问题,子进程输出和父进程到达同一位置

请尝试以下代码: python fork.py python fork.py 1 看看它能做什么。

#!/usr/bin/env python2

import os
import sys

child_exit_status = 0
if len(sys.argv) > 1:
    child_exit_status = int(sys.argv[1])

pid = os.fork()
if pid == 0:
    print "This is the child"
    if child_exit_status == 0:
        os.execl('/usr/bin/whoami')
    else:
        os._exit(child_exit_status)
else:
    print "This is the parent"
    (child_pid, child_status) = os.wait()
    print "Our child %s exited with status %s" % (child_pid, child_status)

问:为什么子进程可以执行“打印”操作,而它仍然被输出到与父进程相同的位置?