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copied!<p>On Mac OS X 10.8.4, I created a program <code>zombie</code> from <code>zombie.c</code>:</p> <pre><code>#include <stdio.h> #include <stdlib.h> #include <unistd.h> int main(void) { pid_t pid; if ((pid = fork()) >= 0) { if (pid == 0) { printf("%d: committing suicide (parent %d)\n", (int)getpid(), (int)getppid()); exit(0); } else { printf("%d: going to sleep for a while - child %d might die while I snooze\n", (int)getpid(), (int)pid); sleep(30); printf("%d: awake\n", (int)getpid()); } } return 0; } </code></pre> <p>When I ran it in one terminal window, the output was:</p> <pre><code>$ ./zombie 2443: going to sleep for a while - child 2444 might die while I snooze 2444: committing suicide (parent 2443) 2443: awake $ </code></pre> <p>In another terminal window, running <code>ps -f</code> produced:</p> <pre><code> UID PID PPID C STIME TTY TIME CMD 503 260 249 0 12:42PM ttys004 0:00.08 -bash 503 2443 260 0 5:11PM ttys004 0:00.00 ./zombie 503 2444 2443 0 5:11PM ttys004 0:00.00 (zombie) </code></pre> <p>The parenthesize <code>(zombie)</code> is the defunct process, and the name in parentheses is the original name of the process. When I copied the program to <code>living-dead</code>, the corresponding output was:</p> <pre><code> UID PID PPID C STIME TTY TIME CMD 503 260 249 0 12:42PM ttys004 0:00.09 -bash 503 2454 260 0 5:13PM ttys004 0:00.00 ./living-dead 503 2455 2454 0 5:13PM ttys004 0:00.00 (living-dead) </code></pre> <p>(On most systems, the defunct process is marked as <code><defunct></code> or something similar.)</p> <p>Clearly, the value in the <code>PPID</code> column identifies the parent process of the zombie, and the various process IDs match the output from the programs themselves.</p>

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