View source for Rednet.receive

{{lowercase}}
{{Function
|name=rednet.receive
|args=[<nowiki/> [<nowiki/>{{type|string}} protocolFilter, ] {{type|number}} timeout]
|returns={{type|number}} senderID, {{type|any}} message, {{type|string}} protocol
|api=rednet
|addon=ComputerCraft
|desc=Waits for ''timeout'' seconds, or until a [[rednet_message_(event)|rednet_message]] event is found in the event queue (with a matching [[Rednet (API)#Protocols|protocol]], if specified). The system must have a [[modem]] that's been [[rednet.open|readied for rednet usage]] in order for this to function; messages may then be sent to it from remote systems via [[rednet.send|rednet.send()]] / [[rednet.broadcast|rednet.broadcast()]].

Due to the nature of how [[os.pullEvent|events are pulled]], using this function will generally cause the system to discard and ignore any other events that occur until the message is received or the time out ends (though Ctrl+T can generally be used to terminate it, if need be). Likewise, if the system is not specifically listening when a given message is sent, chances are high that another "event-eating" function (eg a [[turtle (API)|turtle movement call]] or most anything else that pauses code execution, such as "sleep") will discard it, making it impossible to "receive". This issue can be bypassed using [[Coroutine (API)|co-routines]] - notably, the [[parallel (API)|parallel API]] offers easy work-arounds.

If a time out value is specified and reached, then {{type|nil}} is returned. Note that protocols are only supported by ComputerCraft 1.6 or later - versions prior returned the distance between the sender and receiver instead (information that can still be gained by inspecting [[modem_message_(event)|modem_message]] events directly, but which may not be "accurate" depending on whether any [[Repeat|Rednet repeaters]] are active on your network).

This command listens on modem channel numbers equal to the system's own [[os.getComputerID|ID]] and 65535 (the latter of which is used for broadcasts). More channels may be opened and listened on by dealing with your modems directly via [[Modem (API)|their own API]].
|examples=
{{Example
|desc=Prints 2 - 4 messages, depending on what's received.
|code=-- Waits until someone sends a message to this computer, then displays it.
 local senderId, message, protocol = rednet.receive()
 print(message)
 
 -- Waits five seconds or until someone sends a message to this computer, then displays it.
 senderId, message, protocol = rednet.receive(5)
 print(message)
 
 -- Waits until someone sends a message to this computer with a protocol of "futons", then displays it.
 senderId, message, protocol = rednet.receive("futons")
 print(message)
 
 -- Waits five seconds or until someone sends a message to this computer with a protocol of "futons", then displays it.
 senderId, message, protocol = rednet.receive("futons",5)
 print(message)
}}
}}

{{RednetAPIFunctions}}

[[Category:API_Functions]]