background rednet

local tBanned={}
myNet={}

local function co() --the coroutine that manages the messages and forwards them, queues events etc
    while true do
        local input={os.pullEventRaw()}
        if input[1]=='rednet_message' then
            table.remove(input,1)
            local t=textutils.unserialize(input[2])
            if t and t[1]=='myNet' and not tBanned[t[3]] then
                tBanned[t[3]]=os.startTimer(2)
                rednet.broadcast(input[2])
                if not t[4] or t[4]==os.computerID() then
                    os.queueEvent('myNet',t[2],t[3])
                end
            end
        elseif input[1]=='timer' then
            for k,v in pairs(tBanned) do
                if v==input[2] then
                    tBanned[k]=nil
                    break
                end
            end
        end
    end
end

function myNet.send(message,id)
    rednet.broadcast(textutils.serialize({'myNet',os.computerID(),message,id}))
end

function myNet.receive(timeout)
    local timed=false
    if type(timeout)=='number' then timed=os.startTimer(timeout) end
    while true do
        local evts={os.pullEvent()}
        if evts[1]=='timer' and evts[2]==timed then
            return nil
        elseif evts[1]=='myNet' then
            return unpack(evts,2)
        end
    end
end

if not fs.exists('bGo') then --1st boot that relaunches shell
    term.clear()
    term.setCursorPos(1,1)
    local oFile=io.open('bGo','w')
    oFile:write('true')
    oFile:close()
    local tThreads={coroutine.wrap(co),coroutine.wrap(function() os.run({},'rom/programs/shell') end)}
    local evts={}
    while true do
        for iNum,fThread in pairs(tThreads) do
            fThread(unpack(evts))
        end
        evts={os.pullEventRaw()}
    end
else --2nd boot where shell has been relaunched, it launches startup2 in case you need another startup file on the PC
    fs.delete('bGo')
    if fs.exists('startup2') then
        shell.run('startup2')
    end
end