Lua variable as a shell command

Hii aLL Im using Awesome Wm and i want to set a shell command as a variable on my rc.lua

i look in Inteet and i found this :

local sh = require ("sh")
local Etheet = awk(cut(grep(ip link(), "[1-9]: en"), -d ":" -f2) , '{print $1}')

Is Give me This Error Msg :

')' expected near 'link'

Can you guy Fix This Command or Give my any other way to do this ???

And Thank you so much