commands.go

package main

import (
	"github.com/codegangsta/cli"
	"log"
)

func LoginCommand(c *cli.Context) {
         //it must be available here
	println(debugFlag)
}

main.go

package main

import (
	"github.com/codegangsta/cli"
	"os"
)

const (
	APIHOST = "xxx"
)

var debugFlag bool

func main() {
	app := cli.NewApp()
	app.Name = "test stuff"
	app.Usage = "xxxx"
	app.Commands = setCommands()

	app.Flags = []cli.Flag{cli.BoolFlag{"debug", "enable debugging"}}
	app.Action = func(c *cli.Context) {
		if c.String("debug") == "true" {
			debugFlag = true
		}

	}
        debugFlag = true
	app.Run(os.Args)
}