如何获取系统调用调用的程序的退出代码？ [英] How to get the exit code of program invoked by system call?

问题描述

例如，Program a.out ：

For example, Program a.out:

int main()
{
    return 0x10;
}

计划 b.out ：

int main()
{
    if(system("./a.out") == 0x10)
       return 0;
    else
       return -1;
}

根据 cppreference ， system（）的返回值是实现相关的。因此，程序b.out的尝试是明显错误的。

According to cppreference, the return value of system() is implementation-dependent. Thus, the attempt of program b.out is obvious erroneous.

在上面的情况下，我如何得到 0x10 而不是未确定值？
如果系统调用不是正确的工具，这是正确的方法是什么？

In the case above, how can I get 0x10 instead of an undetermined value? If system call is not the right tool, what's the proper way to do this?

推荐答案

引用 man system ：

   The value returned is -1 on  error  (e.g.   fork(2)  failed),  and  the
   return  status  of the command otherwise.  This latter return status is
   in the format specified in wait(2).  Thus, the exit code of the command
   will  be  WEXITSTATUS(status).   In case /bin/sh could not be executed,
   the exit status will be that of a command that does exit(127).

您需要使用 WEXITSTATUS 退出代码的命令。您的 bc 需要如下所示：

You need to use WEXITSTATUS to determine the exit code of the command. Your b.c needs to look something like:

#include <stdio.h>
#include <sys/wait.h>
int main()
{
    int ret = system("./a.out");
    if (WEXITSTATUS(ret) == 0x10)
      return 0;
    else
      return 1;
}

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