Output printed twice in 03-live-progress-and-capture-v3.go

[Vinay Calastry]

Line 48 of the code prints the output and the error(if any) from the external command's result.

go-cookbook/advanced-exec/03-live-progress-and-capture-v3.go

But I see that the output is printed first.
Then again under "out:"

I couldn't understand which part of the code is printing the first output.
Using: go version go1.11.2 windows/amd64

[Krzysztof Kowalczyk]

The commentary is in https://blog.kowalczyk.info/article/wOYk/advanced-command-execution-in-go-with-osexec.html

The example is showing how to connect program's output to stdout/stderr, so that you can see output while the program executes:

	stdoutIn, _ := cmd.StdoutPipe()
	stderrIn, _ := cmd.StderrPipe()

	var errStdout, errStderr error
	stdout := io.MultiWriter(os.Stdout, &stdoutBuf)
	stderr := io.MultiWriter(os.Stderr, &stderrBuf)

That is the first output.

And how to also capture the output. That is the second output:

	outStr, errStr := string(stdoutBuf.Bytes()), string(stderrBuf.Bytes())
	fmt.Printf("\nout:\n%s\nerr:\n%s\n", outStr, errStr)

[Vinay Calastry]

Thank you so much. I read the MultiWriter code more carefully and I think I get it now.