$ cat usertest.go
package main

import (
    "fmt"
    "os/user"
)

func main() {
    u, err := user.Current()
    fmt.Printf("current user: %#v %#v\n", u, err)
}

$ GOARCH=amd64 go run usertest.go 
current user: &user.User{Uid:"1000", Gid:"1000", Username:"fd0", Name:"Alexander Neumann", HomeDir:"/home/fd0"} <nil>

$ GOARCH=386 go run usertest.go 
current user: (*user.User)(nil) &errors.errorString{s:"user: Current not implemented on linux/386"}