Returns the global environment table of a Luau thread. With no argument, returns the globals of the calling thread.

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Parameters

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thread
default:"the calling thread"
The thread whose global environment to read. Omitted, it defaults to the thread that called gettenv.

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Returns

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table or nil
The thread’s global environment table, or nil if the thread cannot be read from the current Lua state (see below).

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Behavior

  • Same-VM only. A thread’s globals can only be read from within the same Lua state. If the target thread belongs to a different VM, such as an Actor state, gettenv returns nil rather than reaching across VMs. This is a safety boundary, not a failure to look hard enough.
  • Self short-circuit. Passing the calling thread (or no argument) returns that thread’s globals directly.
  • Per-thread globals. The table returned is the thread’s own globals index. A sandboxed thread has its own globals layered over the shared environment, so what you get back reflects that thread’s view, including any per-thread overrides.
gettenv reads the global environment of a thread. If instead you want the script backing a thread, or the thread backing a script, that lives in the scripts library.

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Example

Read a thread’s globals, guarding against one from another VM:

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Errors

gettenv does not raise. A thread it cannot read yields nil.