Execvp不会在未知命令上返回错误 [英] Execvp doesn't return an error on an unknown command

问题描述

我有以下代码，它会分叉一个孩子并执行命令"a"，这是一个未知命令.但是，execvp不会返回错误，而是显示成功".如果我执行"mv a b"，而文件"a"不存在，也会发生相同的情况.我应该如何捕获和处理这些错误?

I have the following code that forks a child and executes the command "a", which is an unknown command. However, execvp does not return an error and instead, "success" is printed. The same thing happens if I do "mv a b", when the file "a" does not exist. How should I capture and handle these errors?

int main ( int argc, char **argv ){
  pid_t pid;
  char *execArgs[] = { "a", NULL };

  pid = fork();

  // if fork fails
  if (pid < 0){
    exit(EXIT_FAILURE);
  }
  else if (pid == 0){
    execvp(execArgs[0], execArgs);
    if (errno == ENOENT)
      _exit(-1);
    _exit(-2);
  }
  else{
    int status;
    wait(&status); 
    if(!WIFEXITED(status)){
      printf("error\n");
    }
    else{
      printf("success\n");
    }
  }

}

推荐答案

程序已退出；它只是以非零状态退出. WIFEXITED 的主要反义词是 WIFSIGNALED —请参阅 wait() 的POSIX规范.和 WIFSTOPPED 和 WIFCONTINUED 用于其他选项.

The program exited; it just exited with a non-zero status. The primary opposite of WIFEXITED is WIFSIGNALED — see the POSIX specification for wait() and WIFSTOPPED and WIFCONTINUED for the other options.

使用:

int corpse = wait(&status);
if (corpse != -1 && WIFEXITED(status))
{
    int estat = WEXITSTATUS(status);
    char *err = (estat == 0) ? "success" : "failure";
    printf("PID %d exited with status %d (%s)\n", corpse, estat, err);
}
else
    printf("PID %d didn't exit; it was signalled\n", corpse);

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