What does > /dev/null 2>&1 mean?

I came across this recently in a script, so I searched for it to gain an understanding of what it means.

Here’s what I found:

http://www.xaprb.com/blog/2006/06/06/what-does-devnull-21-mean/

 

SSH on Debian: Allow public key access only – no passwords
cd /etc/ssh
cp sshd_config sshd_config.orig
nano sshd_config

Make sure the following three lines are set to “no”. They may be in various locations throughout the file:

PermitRootLogin		no
PasswordAuthentication	no
UsePAM			no

Then restart the service:

/etc/init.d/ssh restart

I learned this at http://www.howtoforge.com/set-up-ssh-with-public-key-authentication-debian-etch