llListen

llListen is a Linden Scripting Language (LSL) function that creates a listener within a script to capture chat messages on a specific channel, with optional filtering by speaker and content. It returns a listen handle that can later be used to remove or control the listener.

The function signature is int llListen(integer channel, string name, key id, string what). The channel parameter selects which chat channel to listen to. The channel value is an integer within the valid LSL range, commonly used values include ordinary chat channels and special system channels. The name parameter filters messages by the speaker’s display name; if name is an empty string, messages from any speaker are considered. The id parameter filters by the speaker’s agent key; if id is NULL_KEY, messages from any speaker are considered. The what parameter filters by message content; if what is an empty string, messages are not filtered by content, otherwise only messages containing what will trigger.

When a message matches all active filters, the script’s listen event is invoked: listen(integer channel, string name, key id, string msg). The channel, speaker name, speaker id, and the message text are provided to the event handler.

Usage and management: llListen returns a handle (an integer) that identifies the listener. The listener can be removed with llListenRemove(handle). Listeners are subject to script and engine limits, so multiple listeners should be used judiciously. See also llListenControl for enabling or disabling a listener and the listen event signature.