英文:
How to use a file as stdin when exec a command
问题
我有这段非常简单的代码：
cmd := exec.Command("cat")
cmd.Stdout = os.Stdout
stdin, _ := cmd.StdinPipe()
file, _ := os.Open("file")
io.Copy(stdin, file)
_ = cmd.Run()
它可以正常工作。但问题是cmd.Run()永远不会返回。似乎在将文件写入stdin后，cat仍然在等待更多内容。
我正在尝试实现cat <file的功能，这种情况下，cat在读取完文件后会退出。
我想知道如何在Go语言中实现这一点？
英文:
I have this very simple code:
cmd := exec.Command("cat")
cmd.Stdout = os.Stdout
stdin, _ := cmd.StdinPipe()
file, _ := os.Open("file")
io.Copy(stdin, file)
_ = cmd.Run()
It works. But the problem is that cmd.Run() never returns. It seems after writing the file to stdin, cat still waits for more content.
I'm trying to do what cat <file does, in which case cat would exit after reading the file.
I wonder how to achieve that in go?
答案1
得分: 3
这是因为你没有关闭 stdin。在 io.Copy 之后添加 stdin.Close()。然后 cat 就会终止。
另外，我知道这只是一个示例，但是完全没有错误检查。我猜这只是为了说明目的。 
英文:
It's because you you don't close the stdin. Add stdin.Close() after io.Copy. cat will then terminate.
Also, I know it's just an example but there is absolutely no error checking. I assume that's just for illustration purposes.
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