如何在c中创建一个linux管道示例-Howtocreatealinuxpipelineexampleinc

3  

Try this:

#include 
#include 
#include 
#include 

int main(int argc, char** argv)
{
 int pipefd[2];
 int childpid,childpid2;
 char* cmd[3]={"ls",NULL,NULL};
 char* cmd2[3]={"grep",".c",NULL};
 pipe(pipefd);
 if(childpid=fork()){
   //parent
   close(pipefd[1]);
   dup2(pipefd[0],STDIN_FILENO);
   execvp("grep",cmd2);
 }else{  
   //child
   //write
   close(pipefd[0]);
   dup2(pipefd[1],STDOUT_FILENO);
   execvp("ls", cmd);
 }
 return 0;
}

2  

Actually the program exits right away — in fact, the parent process exits before the children run, which is why there's a shell prompt before "test.c".

实际上程序会立即退出 - 事实上,父进程在子进程运行之前退出,这就是为什么在“test.c”之前有一个shell提示符。

You can improve things a bit by adding this in your parent:

您可以通过在父级中添加它来改进一些事情:

wait(childpid);
wait(childpid2);

which will make the parent exit after both children.

这将使父母在两个孩子之后退出。

1  

Your program quits immediately, while your processes run in the background. They overwrite the prompt, and makes you think the program is still running even though the shell is waiting for your input (press enter or type a command blindly and see.

当您的进程在后台运行时,您的程序会立即退出。它们会覆盖提示,并让您认为程序仍在运行,即使shell正在等待您的输入(按回车键或盲目输入命令并查看。

You only see test.c because that's the only matching file in your directory (also note that you're checking for "filenames containing c anywhere except the first character", not "ending in .c" which would be grep '\.c$').

你只看到test.c,因为那是你目录中唯一匹配的文件(还要注意你要检查“除第一个字符以外的任何地方都包含c的文件名”,而不是“以.c结尾”,这将是grep'\ .c。 $“)。

The simple fix is to add:

简单的解决方法是添加:

wait(NULL); wait(NULL);

right before your return 0.

就在你回来之前0。