从已编译的二进制文件中读取命令行标志

Question

I created a simple program where I set 2 flags and build it. How to read these flags and set this 2 values from compiled binary?

I tried to read the file many ways but I did not find the flag value.

flag.go

var (
    name *string
    version *int
)

func init(){
    name = flag.String("name","test", "a string")
    version = flag.Int("version", 1.0, "an int")
}

func main(){
    flag.Parse()
    fmt.Println("name : ", *name)
    fmt.Println("version : ", *version)
}

main.go

func main(){
    path := "/Users/____/Desktop/flag"

    dat,_ := ioutil.ReadFile(path)

    strings.Contains(string(dat),"name")

    fmt.Println("%s opened
", dat)
}

I want to find flag value from compiled binary a store it to main program variable. Something like that

var flagMain = test var versionMain = 1.0

Answer 1

flag.Parse() is a runtime operation.

Reading back an embedded value means said value was embedded at compile time.
See AgentZombie go-embed-version as an example:

go build -o /tmp/versserv -ldflags "-X github.com/AgentZombie/go-embed-version/cmd.Version=foo" server/server.go

Then you can call your binary, which can return the embedded value.
Same idea in GoogleContainerTools/container-diff commit 367eb42 from PR 304.
This is automated (again as an example) in ahmetb/govvv