tmux Stalker

Overview

Read content from any tmux pane to gather context during investigations, debugging, or operational tasks. Access visible content, full scrollback history, and pane metadata without switching terminal context.

When to Use

•Investigating errors or issues shown in another pane
•Checking output from long-running processes (builds, tests, servers)
•Gathering context from multiple terminal workspaces
•Reviewing command history from another session
•Understanding what's happening across your terminal environment

Quick Reference

Task	Command
List all panes	`tmux list-panes -a -F "#{session_name}:#{window_index}.#{pane_index} [#{pane_current_command}] #{pane_current_path}"`
List sessions	`tmux list-sessions`
Capture visible content	`tmux capture-pane -t TARGET -p`
Capture full history	`tmux capture-pane -t TARGET -p -S - -E -`
Get pane details	`tmux display -t TARGET -p "cmd: #{pane_current_command}, path: #{pane_current_path}, pid: #{pane_pid}"`

Target Syntax

Panes are addressed as session:window.pane:

•mysession:1.2 - Session "mysession", window 1, pane 2
•:1.2 - Current session, window 1, pane 2
•%5 - Pane ID 5 (unique across all sessions)

Workflow

dot

digraph tmux_workflow {
    "Need terminal context?" [shape=diamond];
    "List panes to find target" [shape=box];
    "Identify relevant pane" [shape=box];
    "Capture content" [shape=box];
    "Analyze and continue" [shape=box];

    "Need terminal context?" -> "List panes to find target" [label="yes"];
    "List panes to find target" -> "Identify relevant pane";
    "Identify relevant pane" -> "Capture content";
    "Capture content" -> "Analyze and continue";
}

Useful Format Variables

When listing panes, these variables provide context:

Variable	Description
`#{session_name}`	Session name
`#{window_index}`	Window number
`#{pane_index}`	Pane number within window
`#{pane_current_command}`	Currently running command
`#{pane_current_path}`	Working directory
`#{pane_pid}`	Process ID
`#{pane_title}`	Pane title (set by applications)
`#{history_size}`	Lines in scrollback

Examples

Find a pane running a specific command:

bash

tmux list-panes -a -F "#{session_name}:#{window_index}.#{pane_index} #{pane_current_command}" | grep -i "npm\|node\|go"

Capture last 500 lines from a pane:

bash

tmux capture-pane -t mysession:1.2 -p -S -500

Get full scrollback history:

bash

tmux capture-pane -t mysession:1.2 -p -S - -E -

Search for error in all pane metadata:

bash

tmux list-panes -a -F "#{session_name}:#{window_index}.#{pane_index} - #{pane_title} - #{pane_current_command}"

Capture-Pane Flags

Flag	Purpose
`-p`	Print to stdout (required for capture)
`-t TARGET`	Specify target pane
`-S START`	Start line (`-` = beginning of history)
`-E END`	End line (`-` = end of visible)
`-J`	Join wrapped lines
`-N`	Preserve trailing spaces

Common Patterns

Debugging a failing test:

•List panes to find test runner: tmux list-panes -a -F "..."
•Capture the test output: tmux capture-pane -t TARGET -p -S -200
•Analyze the error and continue investigation

Checking server logs:

•Find the server pane by command (node, python, go run)
•Capture recent output for context
•Look for errors, warnings, or relevant log entries

Cross-session investigation:

•List all sessions: tmux list-sessions
•List panes in target session: tmux list-panes -t SESSION
•Capture content from relevant panes

Limitations

•Read-only: Cannot send commands to panes (by design)
•Requires tmux server running
•Content capture is point-in-time (no live streaming)
•Very large scrollback buffers may be slow to capture