How to Print Command Line Output from Silent Go Applications Compiled with `-ldflags -H=windowsgui`?

Silent Go Applications and Command Line Output with Windows GUI Flag

In Go applications, compiling with -ldflags -H=windowsgui disables console access, preventing output from printing to the command window. To resolve this issue and print version information to the command prompt, the following steps can be taken:

The underlying problem is that the executable's PE header contains the "Windows" subsystem variable, which disassociates the process from any console. To print to the command prompt, explicit console attachment is required.

Go's syscall package provides the AttachConsole function to achieve this. The code below demonstrates its usage:

package main

import (
    "fmt"
    "syscall"
)

const (
    ATTACH_PARENT_PROCESS = ^uint32(0) // (DWORD)-1
)

var (
    modkernel32 = syscall.NewLazyDLL("kernel32.dll")

    procAttachConsole = modkernel32.NewProc("AttachConsole")
)

func AttachConsole(dwParentProcess uint32) (ok bool) {
    r0, _, _ := syscall.Syscall(procAttachConsole.Addr(), 1, uintptr(dwParentProcess), 0, 0)
    ok = bool(r0 != 0)
    return
}

func main() {
    ok := AttachConsole(ATTACH_PARENT_PROCESS)
    if ok {
        fmt.Println("Okay, attached")
    }
}

After attaching to the parent process's console, the program can print to the command prompt using fmt.Println as usual.

Additionally, for a complete solution, consider handling failure scenarios by either creating a new console window with AllocConsole() or displaying a GUI dialog to inform the user about the issue.

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