# active_window_index

Source: https://libtmux.org/en/tmux/3.7c/catalog/formats/active_window_index/

> Index of active window in session

format variable tmux3.7c

Index of active window in session

* Scope

  Describes the session being formatted

* Type

  Text

* Usage

  `#{active_window_index}`

## Description[#](https://libtmux.org/en/tmux/3.7c/catalog/formats/active_window_index/#description)

Index of active window in session

## Releases[#](https://libtmux.org/en/tmux/3.7c/catalog/formats/active_window_index/#releases)

* [tmux 3.7c](https://libtmux.org/en/tmux/3.7c/catalog/formats/active_window_index/) : present
* [tmux 3.2a](https://libtmux.org/en/tmux/3.2a/catalog/formats/active_window_index/) : present

## Source[#](https://libtmux.org/en/tmux/3.7c/catalog/formats/active_window_index/#source)

* Defined in

  [`format.c:3182`](https://github.com/tmux/tmux/blob/e476c1230b958df0cb12977517d24b3dc931375b/format.c#L3182)

* C source reference

  [`format_cb_active_window_index`](https://libtmux.org/en/tmux/3.7c/reference/c-function-format-c-format_cb_active_window_index/)

* CLI Manual

  [Original manual entry](https://libtmux.org/en/tmux/3.7c/manual/full/#active_window_index)

## Used by[#](https://libtmux.org/en/tmux/3.7c/catalog/formats/active_window_index/#used-by)

Library documentation that names this format variable.

* Go

  [`tmux.FormatValues.ActiveWindowIndex`](https://libtmux.org/en/go/latest/reference/tmux-formatvalues-activewindowindex/), [`tmux.Session.ActiveWindowIndex`](https://libtmux.org/en/go/latest/reference/tmux-session-activewindowindex/)