# LibTmux::Pane#capture

- **Module:** LibTmux
- **Package:** libtmux
- **Language:** Ruby
- **Kind:** method
- **Source:** https://github.com/libtmux/libtmux-ruby/blob/da7b6191b9439e3c84fa1c9eeaa9168263ee7af4/gems/libtmux/lib/libtmux/entity.rb#L178
- **Page:** https://libtmux.org/en/ruby/v0.1.1/reference/libtmux-pane-capture/

```
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, poll the pane until its output line appears, then capture it. Match a whole output line so the echoed command cannot satisfy the check. 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 `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/da7b6191b9439e3c84fa1c9eeaa9168263ee7af4/examples/api/capture.rb).

```ruby
# frozen_string_literal: true

begin
  # docs:begin main
  require "libtmux"

  LibTmux::Server.start do |server|
    created = server.new_session(
      name: "capture", command: ["/bin/sh"],
      environment: {"ENV" => "/dev/null"}, receipt: true
    )
    pane = created.pane
    pane.send_text("printf '\\nlibtmux capture ready\\n'")
    pane.send_keys("Enter")
    deadline = Process.clock_gettime(Process::CLOCK_MONOTONIC) + 5
    captured = pane.capture.stdout.lines(chomp: true)
    until captured.include?("libtmux capture ready")
      raise "Output did not arrive within five seconds" if Process.clock_gettime(Process::CLOCK_MONOTONIC) > deadline
      sleep 0.05
      captured = pane.capture.stdout.lines(chomp: true)
    end
    raise "Expected output is absent from the pane" unless captured.include?("libtmux capture ready")
    puts "libtmux capture ready"
  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 capture.rb
```

Expected output:

```text
libtmux capture ready
```

## Parameters

- `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`)

## tmux command

The tmux commands behind `capture`.

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

## tmux C API

The C declarations in tmux that implement these commands.

- [`cmd_capture_pane_entry`](/en/tmux/latest/reference/c-variable-cmd_capture_pane_entry/) (attribute)
- [`cmd_capture_pane_exec`](/en/tmux/latest/reference/c-function-cmd-capture-pane-c-cmd_capture_pane_exec/) (function)

## Guides

Pages that discuss `capture`.

### Guides

- [Server bindings](/en/ruby/v0.1.1/guides/core/)

### Mcp

- [MCP server guide](/en/ruby/v0.1.1/mcp/source-guide/)

## In other ports

Read a pane’s visible contents

| Language | Equivalent |
| --- | --- |
| 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.capture`](/en/java/latest/reference/io-github-libtmux-pane-pane-capture/) (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) |
| C# | [`LibTmux.Pane.CaptureAsync`](/en/csharp/latest/reference/libtmux-pane-captureasync/) (method) |
| F# | [`LibTmux.FSharp.Pane.capture`](/en/fsharp/latest/reference/libtmux-fsharp-pane-capture/) (function) |
| C++ | [`libtmux::Pane::capture`](/en/cxx/latest/reference/libtmux-pane-capture/) (method) |
| Swift | [`Server.capture(_:includingHistory:)`](/en/swift/latest/reference/server-capture(_-includinghistory-)/) (method) |

No equivalent is recorded in PowerShell, Julia or Elixir.