# Libtmux.Environment.lookup

- **Module:** Libtmux
- **Package:** libtmux
- **Language:** OCaml
- **Kind:** function
- **Source:** https://github.com/libtmux/libtmux-ocaml/blob/205dfda49742592b479247049d186956e4a4cfe9/lib/libtmux.mli#L810
- **Public owner:** Libtmux
- **Page:** https://libtmux.org/en/ocaml/latest/reference/libtmux-environment-lookup/

```
val lookup : t -> string -> value option
```

No I/O. `None` means absent from the selected table and visibility. `Removed` masks a global value; `Value ""` is an explicitly empty value. Names must be ASCII identifiers; values preserve non-NUL bytes.

## Parameters

- `arg1` (`t`)
- `arg2` (`string`)