replace tab with 4 space

tab2space.lua

local function tab2space(filename)
    local lines = {}
    io.input(filename)
    for line in io.lines() do
        table.insert(lines, line)
    end

    local newLine = {}

    for _, line in ipairs(lines) do
        line = string.gsub(line, "\t", "    ")
        -- print(line)
        table.insert(newLine, line)
    end

    local allLine = table.concat(newLine, "\n")

    local fp = io.open(filename, "w")
    io.output(fp)
    io.write(allLine)
    io.close(fp)
end

tab2space("PlaySceneGA.lua")

if you'r using OS X, there is a command /usr/bin/tab2space