GitHub/Codespace/Q/Does starting tmux in a GitHub Codespace keep it alive?

• Does starting tmux in a GitHub Codespace keep it alive?

  • AI Answer

    • AI/Response
      • Short answer: No. tmux keeps processes running within the container while it is running, but does not prevent the GitHub/Codespace from timing out due to inactivity. When the Codespace stops, tmux and all its sessions stop with it.
      • Key distinction — container vs. session:
        • tmux preserves shell sessions and long-running processes inside the container.
        • GitHub/Codespace timeout is governed by GitHub's inactivity detection, not by what processes are running inside the container.
      • What GitHub counts as activity:
        • Active client connections: browser editor, VS Code with the Codespaces extension, or an open gh codespace ssh session.
        • Terminal output — GitHub's docs state that ongoing terminal output resets the idle timer; however, a community discussion (still open as of early 2025) reports this does not always work reliably.
      • What happens when the Codespace times out:
        • The container hibernates; all processes (including tmux) are stopped.
        • File system changes are preserved; in-memory state (tmux sessions, running processes) is lost.
        • On reconnect the Codespace restarts, but tmux sessions from before the stop are gone unless you use a plugin like tmux-resurrect.
      • Where tmux IS useful in a Codespace:
        • If you SSH in via gh codespace ssh, the active SSH connection itself keeps you "connected." Within that session, tmux lets you detach/reattach without losing processes for as long as the SSH link is up.
        • Multiplexing multiple terminal windows and running long jobs you can check on during the same connected session.
      • Workarounds to extend uptime:
        • Increase the idle timeout (default 30 min, max 4 hours) in GitHub Codespaces user preferences.
        • Keep an active gh codespace ssh connection open in a local terminal.
        • For truly persistent background jobs, consider GitHub Actions or a self-hosted runner instead of a Codespace.