# LibTmux::Hooks#set

- **Module:** LibTmux
- **Package:** libtmux
- **Language:** Ruby
- **Kind:** method
- **Source:** https://github.com/libtmux/libtmux-ruby/blob/da7b6191b9439e3c84fa1c9eeaa9168263ee7af4/gems/libtmux/lib/libtmux/options.rb#L170
- **Page:** https://libtmux.org/en/ruby/v0.1.1/reference/libtmux-hooks-set/

```
def set: (
  ::String,
  command: ::String,
  ?index: ::Integer?,
  ?append: bool,
  ?timeout: ::Numeric,
  ?cancel: untyped
) -> ::LibTmux::CommandResult
```

Behavior: Options and hooks.

Behavior contract: Options and hooks.

## Examples

Set and read a session option, convert its value to an Integer, and attach a hook command to the same session. Use Ruby 3.3 or newer with Bundler, and tmux 3.3a or newer, on Unix with `/bin/cat` and `/bin/sh` available. In an empty directory, save this `Gemfile`:

```ruby
source "https://rubygems.org"

gem "libtmux", "0.1.1"
```

Save this complete program as `options.rb`. Its `Server.start` block owns a private tmux server and stops it on exit, including after an error.

[Source example](https://github.com/libtmux/libtmux-ruby/blob/da7b6191b9439e3c84fa1c9eeaa9168263ee7af4/examples/api/options.rb).

```ruby
# frozen_string_literal: true

begin
  # docs:begin main
  require "libtmux"

  LibTmux::Server.start do |server|
    session = server.new_session(name: "work", command: ["/bin/cat"])
    session.options.set("history-limit", 5000)
    limit = session.options.get("history-limit")
    puts "history-limit: #{limit.as(:integer)}"
    puts "inherited: #{limit.inherited?}"
    session.hooks.set("after-new-window", command: "display-message created")
    puts "hook: #{session.hooks.get('after-new-window').as(:string)}"
  end
  # docs:end main
rescue StandardError => error
  warn "#{error.class}: #{error.message}"
  exit 1
end
```

Install the gem and run the program. An operation or cleanup error makes it exit unsuccessfully:

```console
$ bundle install && \
  bundle exec ruby options.rb
```

Expected output:

```text
history-limit: 5000
inherited: false
hook: display-message created
```

## Parameters

- `arg1` (`::String`)
- `command` (`::String`)
- `index` (`::Integer?`)
- `append` (`bool`)
- `timeout` (`::Numeric`)
- `cancel` (`untyped`)

## Raises

- `ArgumentError`

## tmux command

The tmux commands behind `set`.

- [`set-hook`](/en/tmux/latest/manual/set-hook/)

## tmux C API

The C declarations in tmux that implement these commands.

- [`cmd_set_hook_entry`](/en/tmux/latest/reference/c-variable-cmd_set_hook_entry/) (attribute)
- [`cmd_set_option_exec`](/en/tmux/latest/reference/c-function-cmd-set-option-c-cmd_set_option_exec/) (function)

## tmux hooks

Events that run tmux commands, with the scope each hook belongs to and where tmux fires it.

- [Hooks](/en/tmux/latest/catalog/hooks/) (hook)