fork（）返回值与该过程的ps命令输出不同

Question

pid = fork();

if (pid == 0)
{
  pid = execve(command, args, envvars);

  if (pid == -1)
  {
    printf("failed to execute: %s\n", command);
  }
}
else if (pid > 0)
{
  if (strcmp(rootcmd, C_EXEC) == 0)
  {
    wait(pid);

    /** Reap any zombie processes that hang around */
    while ((pid = waitpid(-1, (int *)&status, WNOHANG)) > 0)
    {
    }

    pid = 0;
  }
}
printf("%d\n", pid);

In the above code, pid value of the child process doesn't match with the pid found in the ps -ax command output. In the example I tried, the pid value returned from the ps -ax command is 17 and the pid value returned from the fork() is 1701969937. Can someone help me understand, why the values are different?

Answer 1

Notice, -ax param means, that you want to show not only your processes, but ALL of them. Maybe, in the table you see UID+PID instead of pid. Use

ps -ef | pg

instead. What do you see there?

To see every process on the system using standard syntax:

ps -e
ps -ef
ps -eF
ps -ely 

To see every process on the system using BSD syntax:

ps ax
ps axu 

Are you sure you need BSD syntax?