PROBLEM:

• Sometimes you want to start a process and forget about it. If you start it from the command line, like this:

redshift

• you can’t close the terminal, or it will kill the process. Can you run a command in such a way that you can close the terminal without killing the process?

SOLUTION 1:

• close a terminal without killing the command running in it
• One of the following 2 should work:

$ nohup redshift &

OR

$ redshift &
$ disown

SOLUTION 2:

• If your program is already running you can pause it with Ctrl-Z, pull it into the background with bg and then disown it, like this:

$ sleep 1000
^Z
[1]+  Stopped                 sleep 1000
$ bg
$ disown
$ exit

SOLUTION 3:

• The reason that the process is killed on termination of the terminal is that the process you start is a child process of the terminal. Once you close the terminal, this will kill these child processes as well.
• You can see the process tree with pstree, for example when running kate & in Konsole:

init-+
     ├─konsole─┬─bash─┬─kate───2*[{kate}]
     │         │      └─pstree
     │         └─2*[{konsole}]

• To make the kate process detached from konsole when you terminate konsole, use nohup with the command, like this:

nohup kate &

• After closing konsole, pstree will look like this:

init-+ 
|-kate---2*[{kate}

• and kate will survive.
• An alternative is using screen/tmux/byobu, which will keep the shell running, independent of the terminal.

SOLUTION 4:

• You can run the process like this in the terminal

setsid process

• This will run the program in a new session

SOLUTION 5:

• use a variant on screen,the  command  like this

screen bash -c 'long_running_command_here; echo; read -p "ALL DONE:"'

• The session can be disconnected with Ctrl A Ctrl D and reconnected in the simple case with screen -r. you have this wrapped in a script called session that lives in my PATH ready for convenient access:

#!/bin/bash
#
if screen -ls | awk '$1 ~ /^[1-9][0-9]*\.'"$1"'/' >/dev/null
then
    echo "WARNING: session is already running (reattach with 'screen -r $1')" >&2
else
    exec screen -S "$1" bash -c "$@; echo; echo '--------------------'; read -p 'ALL DONE (Enter to exit):'"
    echo "ERROR: 'screen' is not installed on this system" >&2
fi
exit 1

• This only works when you know in advance you want to disconnect a program. It does not provide for an already running program to be disconnected.

SOLUTION 6:

• prefer:(applicationName &)

Example:

           linux@linux-desktop:~$ (chromium-browser &)

• Make sure to use parenthesis when type the command!

SOLUTION 7:

• You can set a process (PID) to not receive a HUP signal upon logging out and closing the terminal session.
• Use the following command:

nohup -p PID