Using disown

So let’s start a job in the shell.

firefox &

This will start the job in the background of the shell, but it will still be a child of the terminal. We can confirm by running jobs. If we want to keep the application running after we close or disconnect from the shell, then we need to use disown. If we have multiple jobs, then we can also use %n

firefox &
disown

firefox &
code &
disown %1

Putting it all together while ignoring stdout and stderr in the terminal

firefox >/dev/null 2>&1 & disown

Yes the disown applies to the same command and not any currently active job

nohup

nohup, is an application that executes another application such that it won’t receive a SIGHUP when the shell receives the hang up signal. Typically, we also need to redirect stdout and stderr if we don’t want the creation of a nohup.out file which is the default behaviour.

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

In this command, we are informing the shell, to redirect output to /dev/null (a place that discards everything that is written to it, and returns an End of File - EOF if read from). We also inform the shell to redirect the stderr (2) to wherever the stdout (1) is directed (&) to.

Using dex for Desktop Entries

Another way is to use dex to run the “Exec” value of a .desktop file if the entry type is Application.

dex /usr/share/applications/firefox.desktop

Desktop entries - ArchWiki

Subshell

Run the command (with bg) in a sub-shell like so

(firefox &)

To ignore output,

(firefox >/dev/null 2>&1 &)