Question

我在Centos4上发现popen（）的手册页部分说明了：

DESCRIPTION
   The  pclose()  function shall close a stream that was opened by popen(), wait for the command to termi-
   nate, and return the termination status of the process that was running  the  command  language  inter-
   preter.   However, if a call caused the termination status to be unavailable to pclose(), then pclose()
   shall return -1 with errno set to [ECHILD] to report this situation.

但是，在我的C ++应用程序中，当我实际执行代码时，我看到终止状态向左移动了8位。也许这是为了区分-1和管道的终止状态和pclose（）自己的退出状态-1？

这是便携行为吗？为什么手册页没有提到这个？如果不可移植，哪些平台符合这种行为？

Answer 1

只需在shooper的答案中添加一些代码，您可能希望在此代码上做一些事情：

#include <sys/wait.h>

//Get your exit code...
int status=pclose(pipe);

//...and ask how the process ended to clean up the exit code.
if(WIFEXITED(status)) {
    //If you need to do something when the pipe exited, this is the time.
    status=WEXITSTATUS(status);
}
else if(WIFSIGNALED(status)) {
    //If you need to add something if the pipe process was terminated, do it here.
    status=WTERMSIG(status);
}
else if(WIFSTOPPED(status)) {
    //If you need to act upon the process stopping, do it here.
    status=WSTOPSIG(status);
}

除此之外，请根据需要添加优雅。

Answer 2

如果你考虑一下，就会有一个＆＃34; fork＆＃34;在那里，所以你可能想要＆＃34; WIFEXITED＆＃34;和＆＃34; WEXITSTATUS＆＃34;。

从手册页：

pclose（）函数等待关联的进程终止并返回wait4（2）返回的命令的退出状态。

在所有平台上，pclose（）返回管道的终止状态是否向左移8位？

2 个答案: