On Debian 13 (or any Linux system), when running a program that uses GLib's main event loop (e.g., GMainLoop) over SSH, you may encounter issues if the program relies on graphical interfaces or interactive terminal features. SSH sessions, especially non-interactive ones, often lack the necessary environment or display capabilities for GUI-based applications.

Here’s how to ensure a GLib-based program works correctly over SSH:

1. Check if the Program Requires a GUI

If your program uses GTK, GLib with GUI components, or any graphical backend, it will fail over a plain SSH session because there is no display server available.

Solutions:

• Run with X11 Forwarding: If the program requires a GUI, enable X11 forwarding when connecting via SSH:

  bash

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  ssh -X user@debian13-host

  or for better performance (trusted networks only):

  bash

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  ssh -Y user@debian13-host

  Ensure the remote system has xauth installed and X11 forwarding is allowed in /etc/ssh/sshd_config:

  text

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  X11Forwarding yes
  X11DisplayOffset 10

• Use a Virtual Display (Xvfb): If you don’t have a physical display, use Xvfb (X Virtual Framebuffer) to simulate one:

  bash

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  sudo apt install xvfb
  Xvfb :1 -screen 0 1024x768x24 &
  export DISPLAY=:1
  ./your_glib_program

2. Ensure Proper Environment for Non-GUI Programs

If your program is non-GUI (e.g., a daemon or CLI tool using GLib for event loops), ensure:

• The SSH session is interactive (not a script or ssh user@host "command").
• The program does not depend on terminal-specific features (e.g., stdin/stdout for event loops).

Solutions:

• Use screen or tmux: Run the program in a persistent terminal session:

  bash

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  ssh user@debian13-host
  screen -S glib_session
  ./your_glib_program

  Detach with Ctrl+A, D and reattach later.

• Redirect Input/Output: If the program expects terminal input, provide it explicitly or redirect:

  bash

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  ./your_glib_program < input.txt > output.txt

3. Debugging GLib Issues

If the program crashes or hangs:

• Check for Errors: Run with G_MESSAGES_DEBUG=all to see GLib debug messages:

  bash

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  G_MESSAGES_DEBUG=all ./your_glib_program

• Verify Dependencies: Ensure all required libraries (e.g., libglib2.0-0, libgtk-3-0) are installed:

  bash

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  sudo apt install libglib2.0-dev libgtk-3-dev

• Test Locally First: Run the program on the local machine (not via SSH) to confirm it works outside of SSH.

4. Common Pitfalls

• Missing DISPLAY: If the program fails with Error: Can't open display, set the DISPLAY variable:

  bash

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  export DISPLAY=:0

  (Replace :0 with the correct display if using X11 forwarding.)

• SSH Timeout: If the SSH session disconnects, the program may terminate. Use nohup or disown:

  bash

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  nohup ./your_glib_program &
  disown -h %1

• Permissions: Ensure the user has permissions to access /dev/dri, /dev/video*, or other hardware devices if the program interacts with them.

5. Example: Running a GLib-Based CLI Tool

If your program is a CLI tool (e.g., using GMainLoop for async I/O):

ssh user@debian13-host
./your_glib_cli_tool

If it hangs, check if it waits for terminal input. Redirect input or use screen.

Summary Table

Next Steps

If you’re still facing issues, share:

• The exact error message (if any).
• Whether the program is GUI or CLI.
• The command you’re using to run it.

This will help narrow down the solution!