Recode via lua - how to

local function convertEncoding(str, fromEncoding)
    if not str then
        return 'ret-free'
    end

    local sanitizedStr = string.gsub(str, "'", "'\\''")
    local command = "echo '" .. sanitizedStr .. "' | iconv -f " .. fromEncoding .. " -t utf8"
    local handle = io.popen(command)

    if not handle then
        print('Error: iconv does not work.')
        return str
    end

    local result = handle:read("*a")
    handle:close()
    return result
end

function string.toutf8(str)
    return convertEncoding(str, 'iso8859-5')
end

local function processField(data, fieldName, encodingFunc)
    if data[fieldName] then
        local originalValue = data[fieldName]
        local convertedValue = encodingFunc(originalValue)
        data[fieldName] = string.gsub(convertedValue, "\n", "")
    end
end

print("----- ImportConverter.lua BEGIN -----")

if tostring(Data["0008,0005"]) == 'ISO_IR 144' then
    print('FOUND ISO_IR_144, CHANGE Data.CodePage(0008,0005)=ISO_IR 144 to ISO_IR 192')
    Data["0008,0005"] = 'ISO_IR 192'
    processField(Data, '0008,0080', string.toutf8)
    processField(Data, '0008,0081', string.toutf8)
    processField(Data, '0008,1010', string.toutf8)
    processField(Data, '0008,1070', string.toutf8)
    processField(Data, '0010,0010', string.toutf8)
    processField(Data, '0010,0090', string.toutf8)
    processField(Data, '0011,1105', string.toutf8)
    processField(Data, '0018,1020', string.toutf8)
    processField(Data, '0021,1103', string.toutf8)
    processField(Data, '0021,1109', string.toutf8)
    processField(Data, '0021,1132', string.toutf8)
    processField(Data, '0021,1134', string.toutf8)
    processField(Data, '0021,1135', string.toutf8)
    processField(Data, '0021,1177', string.toutf8)
    processField(Data, '0029,1107', string.toutf8)
end

print("===== ImportConverter.lua END =====")