Pane interaction

Send input to a pane and capture its screen to interact with a running program. Attach and send keys provides examples. Sending keys and Capturing output are task guides; this page covers input defaults, capture ranges, and completion handling.

Typing into a pane¶

Two questions come up every time you send something to a pane: should tmux press Enter afterward, and should tmux interpret what you sent as key names (Enter, C-c) rather than literal characters? Choose both explicitly when a command depends on them.

Type without Enter: pane.SendKeys(ctx, SendKeysRequest{Command: &text, SkipEnter: true})

Type + Enter (default): pane.SendKeys(ctx, SendKeysRequest{Command: &text})

How “literal” is chosen: Literal: true field

Examples¶

Text and Enter can be separate tmux commands. If the second operation fails, the text may already be in the pane. Check the current state before retrying; repeating the whole request can duplicate input.

Send a command line and press Enter:

text := "printf 'hello\\n'"
if err := pane.SendKeys(ctx, tmux.SendKeysRequest{
    Command: &text,
    Literal: true,
}); err != nil {
    return fmt.Errorf("send command: %w", err)
}

Reading a pane back¶

Capture reads the pane’s visible screen by default. Request scrollback when you need earlier output. A capture is a snapshot of terminal contents, including any input echoed by the application.

mpane.Capture returns ([]string, error). Pass a context.Context with a deadline and check the error before using the result. Set the start boundary to ktmux.CaptureBoundary to include scrollback. End: tmux.CaptureBoundary includes the bottom of the visible pane.

lines, err := pane.Capture(ctx, tmux.CapturePaneRequest{})
if err != nil {
    return fmt.Errorf("capture pane: %w", err)
}
for _, line := range lines {
    fmt.Println(line)
}

Waiting for something to finish¶

A send call completes when input reaches tmux. It does not wait for the shell command to finish. Wait for expected output or a completion signal.

Use mserver.WaitFor with a SWaitForRequest when the command can signal tmux’s $wait-for channel. For streaming output, open mpane.OpenObservation(ctx) before sending input so the observation includes the command’s first bytes. Both paths take a context; cancellation bounds how long the caller waits.

For a new command whose exit status matters, use msession.Run and inspect its result. Capturing screen text alone cannot establish the command’s exit status.

Capture pane output shows capture and waiting examples. Waiting and retrying explains completion conditions and timeouts.