function find_var(value)
   for k, v in pairs(_G) do
      if v == value then 
         print('for ' .. value .. ' found ' .. k)
      end
   end
end

x='qwerty'
find_var('qwerty')
print '-------'
y=x
find_var('qwerty')
--[[
output:
for qwerty found x
-------
for qwerty found y
for qwerty found x
--]]

function test(perem)
local qwe=123
i=1
repeat
   n,v = debug.getlocal(1, i)
   if n~=nil then
      message(n.."="..v)
   end
   i=i+1
until n==nil
end


test("A") 

function test(perem)
i=1
repeat
   n,v = debug.getlocal(1, i)
   message(n.."="..v)
   i=i+1
until n==nil
end
test("A") 

function print_perem (perem,name_perem)
  message (name_perem .."="..tostring(perem))
end
A=2
print_perem (A,"A")