``disown`` removes the specified <a href="index.html#syntax-job-control">job</a> from the list of jobs. The job itself continues to exist, but fish does not keep track of it any longer.
Jobs in the list of jobs are sent a hang-up signal when fish terminates, which usually causes the job to terminate; ``disown`` allows these processes to continue regardless.
If no process is specified, the most recently-used job is removed (like ``bg`` and ``fg``). If one or more ``PID``s are specified, jobs with the specified process IDs are removed from the job list. Invalid jobs are ignored and a warning is printed.
If a job is stopped, it is sent a signal to continue running, and a warning is printed. It is not possible to use the ``bg`` builtin to continue a job once it has been disowned.
``firefox &; disown`` will start the Firefox web browser in the background and remove it from the job list, meaning it will not be closed when the fish process is closed.