Running bash commands in the background without printing job and process ids

To run a process in the background in bash is fairly easy.

$ echo "Hello I'm a background task" &
[1] 2076
Hello I'm a background task
[1]+  Done                    echo "Hello I'm a background task"

However the output is verbose. On the first line is printed the job id and process id of the background task, then we have the output of the command, finally we have the job id, its status and the command which triggered the job.

Is there a way to suppress the output of running a background task such that the output looks exactly as it would without the ampersand at the end? I.e:

$ echo "Hello I'm a background task" &
Hello I'm a background task

The reason I ask is that I want to run a background process as part of a tab-completion command so the output of that command must be uninterrupted to make any sense.

Not related to completion, but you could supress that output by putting the call in a subshell:

(echo "Hello I'm a background task" &)

Building off of @shellter's answer, this worked for me:

tyler@Tyler-Linux:~$ { echo "Hello I'm a background task" & disown; } 2>/dev/null; sleep .1;
Hello I'm a background task
tyler@Tyler-Linux:~$

I don't know the reasoning behind this, but I remembered from an old post that disown prevents bash from outputting the process ids.

In some newer versions of bash and in ksh93 you can surround it with a sub-shell or process group (i.e. { ... }).

/home/shellter $ { echo "Hello I'm a background task" & } 2>/dev/null
Hello I'm a background task
/home/shellter $

Based on this answer, I came up with the more concise and correct:

silent_background() {
    { 2>&3 "$@"& } 3>&2 2>/dev/null
    disown &>/dev/null  # Prevent whine if job has already completed
}
silent_background date