# LibTmux::Pane#capture

- **Module:** LibTmux
- **Package:** libtmux
- **Language:** Ruby
- **Kind:** method
- **Source:** https://github.com/libtmux/libtmux-ruby/blob/dcc9f8b5a6970144a9e7d80cd5f381d8f6198372/gems/libtmux/lib/libtmux/entity.rb#L169
- **Page:** https://libtmux.org/en/ruby/v0.1.0.alpha.2/reference/libtmux-pane-capture/

tmux command: [`capture-pane`](/en/tmux/latest/manual/capture-pane/)

```
def capture: (
  ?start: ::Integer | ::String | nil,
  ?finish: ::Integer | ::String | nil,
  ?join: bool,
  ?escapes: bool,
  ?escape_bytes: bool,
  ?preserve_trailing: bool,
  ?trim_trailing: bool,
  ?alternate: bool,
  ?mode_screen: bool,
  ?pending: bool,
  ?timeout: ::Numeric,
  ?cancel: untyped
) -> ::LibTmux::CommandResult
```

Behavior: Pane input and capture.

Behavior contract: Pane input and capture.

## Examples

Send a command to a shell, wait for its output notification, then capture the pane. Match a whole output line so the echoed command cannot satisfy the check. Use Ruby 4.0.7, Bundler, Git and tmux 3.2a or newer on Unix, with /bin/cat and /bin/sh available. In an empty directory, fetch the documented library revision:

```console
$ git clone https://github.com/libtmux/libtmux-ruby.git libtmux-source && \
  git -C libtmux-source checkout dcc9f8b5a6970144a9e7d80cd5f381d8f6198372
```

Save this dependency file as Gemfile:

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

gem "libtmux", path: "libtmux-source/gems/libtmux"
```

Save this complete program as capture.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/dcc9f8b5a6970144a9e7d80cd5f381d8f6198372/examples/api/capture.rb).

```ruby
# frozen_string_literal: true

require "libtmux"

begin
  LibTmux::Server.start do |server|
    created = server.new_session(
      name: "capture", command: ["/bin/sh"],
      environment: {"ENV" => "/dev/null"}, receipt: true
    )
    pane = created.pane
    server.open_control(session: created.entity.ref) do |control|
      control.exchange("display-message -p ready", timeout: 1)
      output = control.subscribe(pane_id: pane.id, max_bytes: 8192, max_events: 32)
      pane.send_text("printf '\\nlibtmux capture ready\\n'")
      pane.send_keys("Enter")
      deadline = Process.clock_gettime(Process::CLOCK_MONOTONIC) + 5
      bytes = "".b
      until bytes.lines(chomp: true).include?("libtmux capture ready")
        remaining = deadline - Process.clock_gettime(Process::CLOCK_MONOTONIC)
        raise "Output did not arrive within five seconds" unless remaining.positive?
        bytes << output.next(timeout: remaining).data
      end
      captured = pane.capture.stdout.lines(chomp: true)
      raise "Expected output is absent from the pane" unless captured.include?("libtmux capture ready")
      puts "libtmux capture ready"
    end
  end
rescue StandardError => error
  warn "#{error.class}: #{error.message}"
  exit 1
end
```

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

```console
$ bundle config set --local path vendor/bundle && \
  bundle install --jobs 2 && \
  bundle exec ruby capture.rb
```

Expected output:

```text
libtmux capture ready
```

## In other ports

### Read a pane’s visible contents

- Python: [`libtmux.Pane.capture_pane`](/en/py/latest/reference/libtmux-pane-capture_pane/) (method)
- Lua: [`libtmux.Pane:capture`](/en/lua/latest/reference/libtmux-pane-capture/) (method)
- TypeScript: [`pane.Pane.capture`](/en/ts/latest/reference/pane-pane-capture/) (method)
- Rust: [`pane.Pane.capture`](/en/rs/latest/reference/pane-pane-capture/) (method)
- Go: [`tmux.Pane.Capture`](/en/go/latest/reference/tmux-pane-capture/) (method)
- Java: [`io.github.libtmux.Pane.Pane.capture`](/en/java/latest/reference/io-github-libtmux-pane-pane-capture/) (method)
- C#: [`LibTmux.Pane.CaptureAsync`](/en/csharp/latest/reference/libtmux-pane-captureasync/) (method)
- C++: [`libtmux::Pane::capture`](/en/cxx/latest/reference/libtmux-pane-capture/) (method)
- Swift: [`Server.capture(_:includingHistory:)`](/en/swift/latest/reference/server-capture(_-includinghistory-)/) (method)
- Kotlin: [`io.github.libtmux.kotlin.Pane.capture`](/en/kotlin/latest/reference/io-github-libtmux-kotlin-pane-capture/) (method)
- Scala: [`io.github.libtmux.scaladsl.Pane.capture`](/en/scala/latest/reference/io-github-libtmux-scaladsl-pane-capture/) (method)
- F#: [`LibTmux.FSharp.Pane.capture`](/en/fsharp/latest/reference/libtmux-fsharp-pane-capture/) (function)