How to redirect a command in Go without outputting the result to Terminal?

I want to run a command: pbcopy < file.csv within my Go program. However, it looks like Go's os/exec package cannot redirect one command to another using < syntax. So I decided to use pipe in my program. However, this script:

package main

import (
	"os/exec"
)

func main() {
	cmd1 := exec.Command("cat", "test.csv")
	cmd2 := exec.Command("pbcopy")
	out, _ := cmd1.StdoutPipe()
	cmd2.Stdin = out
    cmd2.Run()
}

When I run the above program, the program doesn't terminate and it looks like waiting for the input from the user in Terminal. And when I terminate it and try to paste the result to anywhere it doesn't take the input and save it to the clipboard.

Then I change the last line of the program from cmd2.Run() to cmd2.Start(), then the program terminates properly. However, the clipboard is filled with an empty string and not saves the cat file.csv output to clipboard.

I tried to look for some examples to use pipe in os.exec in Go, but all of that I saw assume that the result is output to the Terminal in the end, such as ls -l | wc -l or ls -l | grep "py" or such things. But pbcopy command doesn't display the input and just saves the input to clipboard.

So how can I use a redirect (or pipe) in os.exec package in Go with pbcopy command?

You need to start command 1. Command 2 is waiting for input from command 1 and will likely wait indefinitely.

cmd1.Start()
cmd2.Run()

EDIT: looking back at the question, why are you doing this as two commands in the first place? Instead, you can os.Open("test.csv") and pass the file pointer directly to cmd2.Stdin.