# Options and hooks

Source: https://libtmux.org/en/rs/latest/topics/options-and-hooks/

> Read and update tmux options, and register commands for tmux events.

Use options to change tmux behavior, such as [`automatic-rename`](https://libtmux.org/en/tmux/latest/catalog/options/automatic-rename/) or the
status-line format. Use hooks to run commands on events such as
[`session-renamed`](https://libtmux.org/en/tmux/latest/catalog/hooks/session-renamed/) or [`after-split-window`](https://libtmux.org/en/tmux/latest/catalog/hooks/after-split-window/). Choose the scope supported by the
option or hook.

## Reading and writing options

Read, set, or unset an option at its supported scope. Distinguish a local
override from the effective value inherited from a parent scope.

**Read all (this scope):** [`pane.options()`](<https://libtmux.org/en/rs/latest/reference/pane-pane-options/>) (typed [`BTreeMap`](<https://doc.rust-lang.org/std/collections/struct.BTreeMap.html>)),
[`pane.option_names()`](<https://libtmux.org/en/rs/latest/reference/pane-pane-option_names/>)

**Read effective/inherited:** [`pane.typed_option(name)`](<https://libtmux.org/en/rs/latest/reference/pane-pane-typed_option/>) decodes one value by its
declared kind

**Set:** [`pane.set_option(name, value)`](<https://libtmux.org/en/rs/latest/reference/pane-pane-set_option/>), [`pane.append_option(name, value)`](<https://libtmux.org/en/rs/latest/reference/pane-pane-append_option/>)

**Unset:** [`pane.unset_option(name)`](<https://libtmux.org/en/rs/latest/reference/pane-pane-unset_option/>)

### Examples

After a successful write completes, read the option to obtain its updated value.
The following examples set, read, and unset an option:

```rust
pane.set_option("automatic-rename", "off").await?;
pane.options().await?;
pane.unset_option("automatic-rename").await?;
```

## Hooks

**Set:** [`pane.set_hook(name, command)`](<https://libtmux.org/en/rs/latest/reference/pane-pane-set_hook/>)

**Unset:** [`pane.unset_hook(name)`](<https://libtmux.org/en/rs/latest/reference/pane-pane-unset_hook/>)

**List:** [`pane.hook(name)`](<https://libtmux.org/en/rs/latest/reference/pane-pane-hook/>): one name only; **no listing at pane/window scope**,
by design (see below)

**Run now, without the event:** Not listed.

### Examples

tmux stores hook commands in indexed arrays, such as [`after-new-window[0]`](https://libtmux.org/en/tmux/latest/catalog/hooks/after-new-window/).

Set and list a session hook. The next section explains window and pane scope
limitations:

```rust
session.set_hook("session-renamed", "display-message 'renamed'").await?;
session.hooks().await?;
```

<a id="window-and-pane-hook-scopes-are-mostly-fiction"></a>

## Supported hook scopes

tmux stores hooks globally or per session. Accepted [`set-hook -w`](https://libtmux.org/en/tmux/latest/manual/set-hook/) or `-p` flags
do not imply a separate window or pane hook table, and [`show-hooks`](https://libtmux.org/en/tmux/latest/manual/show-hooks/) does not
provide a corresponding listing. Check the event's supported scope if a hook is
accepted but never fires.

[`Pane::set_hook`](<https://libtmux.org/en/rs/latest/reference/pane-pane-set_hook/>) and [`Window::set_hook`](<https://libtmux.org/en/rs/latest/reference/window-window-set_hook/>) return [`Error::OptionScopeMismatch`](<https://libtmux.org/en/rs/latest/reference/error-error-optionscopemismatch/>)
for an unsupported scope.

Options have window and pane tables of their own. The hook-scope limitation does
not apply to ordinary options.

## tmux version compatibility

Check the library's supported tmux versions before using a version-specific
option or hook.

<details>
<summary>tmux manual and source</summary>

The tmux manual defines [option scopes and inherited reads](https://github.com/tmux/tmux/blob/94796f6b1182507efac8a272fc309a79e22e58a5/tmux.1#L4725).
Unsetting a local value restores inheritance. Hook programs run in tmux when
their event occurs; see the [hook implementation](https://github.com/tmux/tmux/blob/94796f6b1182507efac8a272fc309a79e22e58a5/cmd-set-option.c).

</details>