Question

我创建了以下程序，该程序应该返回进程ID和子进程的退出代码。应该使用非零退出代码打印出进程。我不知道我是否正确地做到了。这是对的吗？

#include <stdio.h>
#include <errno.h>
#include <sys/wait.h>

int main() {
    int pid = fork();

    if (pid < 0) {
        printf("Could not fork\n");
        exit(1);
    }

    else if (pid == 0) {
        execvp(arg[0], arg);
        exit(0);
    }

    else {
        wait(NULL);
        if (errno != 0) {
            printf("%d returned code %d", getpid(), errno);
        }
    }
}

Answer 1

来自人等待 here

   WEXITSTATUS(status)
          returns  the  exit  status  of the child.  This consists of the least significant 8 bits of the status argument that the child specified in a
          call to exit(3) or _exit(2) or as the argument for a return statement in main().  This macro should be employed only  if  WIFEXITED  returned
          true.


Return Value

    wait(): on success, returns the process ID of the terminated child; on error, -1 is returned.

因此大致，您的代码应如下所示

int stat;
pid_t cpid = wait( &stat );

if ( WIFEXITED(stat) ) {
    printf("%d returned code %d", cpid , WEXITSTATUS(stat));
}

打印pid和errno

1 个答案: