d to the /etc directory.

Execute the following command.

ls -l au*.[mn]*

The output is the following:

-rw-r--r-- 1 root root 675 Jan 24 19:04 auto.master

-rw-r--r-- 1 root root 524 Mar 22 2012 auto.misc

-rwxr-xr-x 1 root root 1374 Mar 22 2012 auto.net

This is exactly the output I was hoping for.

What function are the [ ] performing?

		They look good and balance the command string.
		The uniquely match the m and n characters to ensure only the desired output is generated.
		They neutralize the m and n characters to hide the output.
		They were used by mistake and have no meaning.