1 #!/usr/bin/python
   2 # -*- coding: utf-8 -*-
   3 
   4 # Nacitaju sa moduly
   5 import os
   6 import time
   7 import sys
   8 import signal
   9 
  10 # Funkcia zabezpecujuca obsluhu signalu SIGCHLD
  11 # frame je interna pythonovska zalezitost, ignorujme
  12 def handler(signum,frame):
  13         print "Zavolal sa handler, signal = %d" % (signum)
  14         # parent si preberie navratovu hodnotu od jadra
  15         ret_wait=os.wait()
  16         # os.wait vracia v Pythone dvojicu hodnot
  17         pid_chld_wait=ret_wait[0] # pid child procesu
  18         ret_chld=ret_wait[1] >> 8 # a nahratovu hodnotu (shiftnutu)
  19         print "child %d vratil %d" % (pid_chld_wait,ret_chld)
  20 
  21 
  22 if len(sys.argv)<=1:
  23         print "Spust ma s parametrom meno_adresara"
  24         sys.exit(1)
  25 
  26 # Nastavime si osetrovanie signalu o tom, ze ls skoncil
  27 signal.signal(signal.SIGCHLD, handler)
  28 
  29 # Zavolame fork
  30 pid_chld=os.fork()
  31 # child dostane vratene 0, parent dostane PID child procesu
  32 if pid_chld==0:
  33         # Spusti sa ls pre prvy argument
  34         # Prve /bin/ls je co sa ma spustit
  35         # Druhe /bin/ls je argv[0] pre ls - tradicne to je meno programu
  36         time.sleep(1)
  37         print "Este zijem"
  38         os.execlp("/bin/ls","/bin/ls",sys.argv[1])
  39         print "Sem sa nikdy tok riadenia nedostane"
  40 elif pid_chld<0:
  41         print "fork vratil chybu"
  42         sys.exit(1)
  43 else:
  44         print "PID child = %d" % pid_chld
  45         string="parent"
  46 
  47 # Oba procesy bezia sucasne, sem sa ale teraz dostane iba parent
  48 for i in range(20):
  49         print string
  50         time.sleep(0.1)