Sungju's Slow Life

If you are seeing ‘root:root’ under /proc// for your process, it means the process is in Zombie state.

#include 

int main() {
        pid_t pid;
        int i;

        for (i = 0; ; i++)  {
                pid = fork();

                if (pid > 0) {
                        break;
                } else {
                        exit(0);
                }
        }
        while (1) {
            sleep(1);
        }

        return 0;
}

$ gcc -o zombie zombie.c
$ ./zombie &
$ ps aux | grep zombie
sungju   12994  0.0  0.0   3924   340 pts/1    S    11:54   0:00 ./zombie
sungju   12995  0.0  0.0      0     0 pts/1    Z    11:54   0:00 [zombie] 
sungju   13398  0.0  0.0 103320   848 pts/1    S+   11:55   0:00 grep --color zombie

$ ls -l /proc/12994 | head
total 0
dr-xr-xr-x. 2 sungju sungju 0 Jan 30 11:55 attr
-rw-r--r--. 1 sungju sungju 0 Jan 30 11:55 autogroup
-r--------. 1 sungju sungju 0 Jan 30 11:55 auxv
-r--r--r--. 1 sungju sungju 0 Jan 30 11:55 cgroup
--w-------. 1 sungju sungju 0 Jan 30 11:55 clear_refs
-r--r--r--. 1 sungju sungju 0 Jan 30 11:55 cmdline
-rw-r--r--. 1 sungju sungju 0 Jan 30 11:55 comm
-rw-r--r--. 1 sungju sungju 0 Jan 30 11:55 coredump_filter
-r--r--r--. 1 sungju sungju 0 Jan 30 11:55 cpuset

$ ls -l /proc/12995 | head
ls: cannot read symbolic link /proc/12995/cwd: Permission denied
ls: cannot read symbolic link /proc/12995/root: Permission denied
ls: cannot read symbolic link /proc/12995/exe: Permission denied
total 0
dr-xr-xr-x. 2 sungju sungju 0 Jan 30 11:55 attr
-rw-r--r--. 1 root   root   0 Jan 30 11:55 autogroup
-r--------. 1 root   root   0 Jan 30 11:55 auxv
-r--r--r--. 1 root   root   0 Jan 30 11:55 cgroup
--w-------. 1 root   root   0 Jan 30 11:55 clear_refs
-r--r--r--. 1 root   root   0 Jan 30 11:55 cmdline
-rw-r--r--. 1 root   root   0 Jan 30 11:55 comm
-rw-r--r--. 1 root   root   0 Jan 30 11:55 coredump_filter
-r--r--r--. 1 root   root   0 Jan 30 11:55 cpuset