# libtmux.Window.split

- **Module:** libtmux.Window
- **Package:** libtmux
- **Language:** Python
- **Kind:** method
- **Source:** https://github.com/tmux-python/libtmux/blob/036c521c4b83ce6e434eb50afe2a0d08a6a05e46/src/libtmux/window.py#L526
- **Page:** https://libtmux.org/reference/py/libtmux-window-split/

```
libtmux.Window.split(self, target: int | str | None = None, start_directory: StrPath | None = None, attach: bool = False, direction: PaneDirection | None = None, full_window_split: bool | None = None, zoom: bool | None = None, shell: str | None = None, size: str | int | None = None, percentage: int | None = None, environment: dict[str, str] | None = None, empty: bool | None = None, style: str | None = None, active_border_style: str | None = None, inactive_border_style: str | None = None, message: str | None = None, keep: bool | None = None) -> Pane
```

Split window on active pane and return the created :class:`Pane`.

## Parameters

- `self`
- `target` (int | str | None)
- `start_directory` (StrPath | None) — Specifies the working directory in which the new window is created.
- `attach` (bool) — Make new window the current window after creating it, default
True.
- `direction` (PaneDirection | None) — Split in direction. If none is specified, assume down.
- `full_window_split` (bool | None) — Split across full window width or height, rather than active pane.
- `zoom` (bool | None) — Expand pane.
- `shell` (str | None) — Execute a command on splitting the window. The pane will close
when the command exits.
NOTE: When this command exits the pane will close. This feature
is useful for long-running processes where the closing of the
window upon completion is desired.
- `size` (str | int | None) — Cell/row count to occupy with respect to current window.
- `percentage` (int | None) — Percentage (0-100) of the window to occupy (``-p`` flag).
Mutually exclusive with *size*.
- `environment` (dict[str, str] | None) — Environmental variables for new pane. Passthrough to ``-e``.
- `empty` (bool | None) — Create an empty pane with no command (``-E`` flag) instead of
spawning the default shell. Requires tmux 3.7+. If used with
tmux < 3.7, a warning is issued and the flag is ignored.
- `style` (str | None) — Style for the new pane (``-s``). Requires tmux 3.7+.
- `active_border_style` (str | None) — Active-pane border style (``-S``). Requires tmux 3.7+.
- `inactive_border_style` (str | None) — Inactive-pane border style (``-R``). Requires tmux 3.7+.
- `message` (str | None) — Keep the pane open (until a key is pressed) after exit, showing this
``remain-on-exit-format`` message (``-m``). Requires tmux 3.7+.
- `keep` (bool | None) — Keep the pane open until a key is pressed after exit (``-k``).
Requires tmux 3.7+. These 3.7 flags warn and are ignored below 3.7.

## Returns

:class:`Pane`
    The newly created pane.