未知的syscall.SysProcAttr字段'Unshareflags'

I was trying out the Syscall in Go and had created the struct

cmd.SysProcAttr = &syscall.SysProcAttr{
        //New UTS              Child become 1          Mount Name Space
        Cloneflags:   syscall.CLONE_NEWUTS | syscall.CLONE_NEWPID | syscall.CLONE_NEWNS,
        Unshareflags: syscall.CLONE_NEWNS, //Dont share the container to the host,
    }

but I get the error :

unknown syscall.SysProcAttr field 'Unshareflags' in struct literal

From the documentation I understand it does not work in a mac. I tried running it on an Ubuntu VM:

Linux xxx 4.2.0-27-generic #32~14.04.1-Ubuntu SMP Fri Jan 22 15:32:26 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

Doesn't work as a sudo user either.