Shell

How do I detach a process from Terminal, entirely?

To launch an application in detached mode from the Linux terminal, ensuring it continues to run even if the terminal is closed, several methods can be employed:

https://superuser.com/questions/178587/how-do-i-detach-a-process-from-terminal-entirely

emacs &

1. nohup and Backgrounding

   This is a common and effective method. nohup prevents the process from receiving a SIGHUP signal (hangup signal) when the controlling terminal is closed, while & runs the command in the background.

   nohup your_command &
   

   For example, to launch Firefox in detached mode:

   nohup firefox &
   

   To prevent output from cluttering your terminal or nohup.out file, you can redirect standard output and error:

   nohup your_command > /dev/null 2>&1 &
   

2. disown:

   If you already have a process running in the background, you can detach it from the terminal using disown. Start the command in the background.

   your_command &
   

   1. Use jobs to list background processes and identify the job number (e.g., [1]):

      jobs
      

   2. Detach the process using disown with the job number:

      disown %1
      

3. screen or tmux:

   These terminal multiplexers allow you to create persistent terminal sessions that can be detached and reattached later.

   1. Screen

      1. Start a screen session.

      screen
      

      1. Run your command within the screen session.
      2. Detach the screen session: Press Ctrl+A then d.
      3. Reattach later:

         screen -r
         

   2. tmux

      1. tmux offers similar functionality and is a popular alternative to screen.

4. setsid:

   setsid creates a new session and detaches the process from the controlling terminal, making it immune to terminal closure.

   setsid your_command
   

Choosing the right method

1. For simple backgrounding and detachment, nohup and & is often sufficient.
2. If you need to detach an already running background process, disown is useful.
3. For managing multiple persistent terminal sessions or reconnecting to processes later, screen or tmux are powerful tools.
4. setsid is a more robust way to ensure complete detachment from the controlling terminal.

Tags

1. emacs - environment variables
2. Environment variables