C programming : how to create a zombie process

# gcc --version | head -1 gcc (GCC) 4.4.6 20120305 (Red Hat 4.4.6-4) # cat /etc/centos-release CentOS release 6.3 (Final) # uname -ri 2.6.32-279.1.1.el6.i686 i386

# cat create-zombie.c -n     1  #include <stdio.h>     2  #include <sys/types.h>     3  #include <unistd.h>     4  #include <stdlib.h>     5     6  int main()     7  {     8          pid_t c_pid;     9    10          c_pid=fork(); /* crete a child process */    11    12          if (c_pid > 0) { /* child process */    13                  printf("Parent PID : %d\r\n", getpid());    14                  printf("Child PID  %d is zombie process \r\n", c_pid);    15                  sleep (1000);    16          }    17          else {    18                  return 0;    19          }    20  return 0;    21  }

compile it.

# gcc create-zombie.c -o create-zombie.o

run

# ./create-zombie.o Parent PID : 1688 Child PID 1689 is zombie process

check whether or not child process is zombie.

# pstree -p 1688 create-zombie.o(1688)---create-zombie.o(1689)

PID 1689 is marked as a zombie process.

# ps aux | awk '{ print $8 " " $2 }' | grep -w Z Z+ 1689

# top -b -n 1 top - 20:43:31 up 28 min,  2 users,  load average: 0.00, 0.00, 0.00 Tasks: 100 total,   1 running,  98 sleeping,   0 stopped,   1 zombie

# egrep -i state /proc/1689/status State:  Z (zombie)