I wanted to run jupyter notebook background without showing any outputs from it. So I tried the following command, :

$ jupyter notebook hoge.ipynb 2>&1 > /dev/null &

But it still showed some outputs on the screen and interrupted me typing other commands. This is because, 2>&1 means that standard error output goes to where the standard output currently pointing to, which is not /dev/null. So I had to switch the order from 2>&1 > /dev/null to 1>/dev/null 2>&1 to make the error output go to /dev/null. :

$ jupyter notebook hoge.ipynb >/dev/null 2>&1 &
$ jupyter notebook hoge.ipynb 1>/dev/null 2>&1 &