Running Commands in the Background

To ensure commands continue running even if you're disconnected from the shell or SSH, you can use tools like nohup, screen or tmux.

Using nohup

nohup allows a command to run in the background and continue running even after you log out.

nohup cp -R /path/to/SOURCE_FOLDER/* /path/to/DESTINATION_FOLDER/ &

The & at the end runs the command in the background, and nohup ensures it keeps running after logout.

Using screen

screen is a more powerful tool that allows you to create sessions that can be detached and reattached.

1. Start a new screen session:

   screen -S session_name
   

2. Run your command without the & since screen keeps it running:

   rsync -a /path/to/SOURCE_FOLDER/ /path/to/DESTINATION_FOLDER/
   

3. Detach from the screen session by pressing Ctrl+A then D.

You can reconnect to the session later with screen -r session_name.

Using tmux

tmux is another powerful tool, similar to screen, that allows for managing multiple terminal sessions inside a single window. It's especially useful for running long processes in the background, like large data transfers, and for maintaining sessions after disconnection from an SSH or shell session.

Using tmux, you can start a new session, run your command, and detach, with the assurance that your process will continue running in the background. Here’s how to use tmux for our data copying tasks:

1. Starting a New tmux Session: To begin, start a new tmux session by typing:

   tmux new -s session_name
   

   This command creates a new session named session_name.

2. Running Your Command: Within the tmux session, you can run any of the data copying commands previously mentioned. For example, to use rsync:

   rsync -a /path/to/SOURCE_FOLDER/ /path/to/DESTINATION_FOLDER/
   

   There's no need to use & to background the process, as tmux keeps it running inside the session.

3. Detaching from tmux Session: To detach from the session and leave your process running in the background, press Ctrl+B followed by D. This key combination detaches you from the session but leaves it running.

4. Reattaching to a tmux Session: If you need to check the progress of your command or start a new task, you can reattach to your tmux session using:

   tmux attach-session -t session_name
   

   This command reopens your tmux session where you left off.

Benefits of Using tmux

• Multiple Windows and Panes: Unlike nohup, tmux allows for complex window management, including multiple windows and panes within a single session, enhancing productivity and monitoring capabilities.
• Session Management: tmux provides robust session management, allowing you to detach and reattach to sessions as needed, which is ideal for long-running processes or tasks initiated over SSH.
• Customization: tmux supports extensive customization, including key bindings and appearance settings, making it a versatile tool for power users.