build.sh

# Go! Why don't you use my version?
## WRONG: go run -ldflags="-X commonFlagTest.version='my-uber-version'" cmd/flagtest/main.go -version
go run -ldflags="-X github.com/serverhorror/commonFlagTest.versionString='$(TZ=UTC date '+%FT%T.%N%:z')'" cmd/flagtest/main.go -version

commonFlagTest_cmd_flagtest_main.go

package main

import (
        "flag"
        "fmt"

        "github.com/serverhorror/commonFlagTest"
)

var (
        localFlag = flag.Bool("local", false, "Flag local to the main.go file")
)

func main() {
        commonFlagTest.Main()

        if *localFlag {
                fmt.Println("Local Flag")
        }
}

commonFlagTest_common.go

package commonFlagTest

import (
        "flag"
        "fmt"
        "os"
"runtime"
)

var (
        version string

        versionFlag = flag.Bool("version", false, "Print version and exit")
)

func Main() {
        flag.Parse()

        if *versionFlag {
                PrintVersion()
        }
}

func PrintVersion() {
        fmt.Printf("Version: %#q\n", version)
        fmt.Printf("Runtime: %#q\n", runtime.Version())
        os.Exit(1)
}