test.lua

function split(pString, pPattern)
    local Table = {}
    local fpat = "(.-)" .. pPattern
    local last_end = 1
    local s, e, cap = pString:find(fpat, 1)
    while s do
        if s ~= 1 or cap ~= "" then
            table.insert(Table,cap)
        end
        last_end = e+1
        s, e, cap = pString:find(fpat, last_end)
    end
    if last_end <= #pString then
        cap = pString:sub(last_end)
        table.insert(Table, cap)
    end
    return Table
end

rednet.open("top")
id,msg = rednet.receive()
data = split(msg, "-")
user = data[1]
action = data[2]
if action == 1 then
    f = fs.open(user .. ".txt", "r")
    fc = f.readAll()
    f.close
    if tonumber(fc) > 0 then
        w = fs.open(user .. ".txt", "w")
        new = fc - 1
        w.write(new)
        w.close()
        rednet.send(id,"ok")
    else
        rednet.send(id,"no")
    end
end