Here's what's creating it (credit goes to Dave North for figuring out most of this).
It's there because you're in the group admin, and it's there to turn off a silly bash warning. It's specific to Ubuntu (at least, Fedora doesn't do it). Whenever you log in under bash, if bash sees that you're in the admin group in /etc/groups, it prints this warning:
To run a command as administrator (user "root"), use "sudo
See "man sudo_root" for details.
Once you sudo to root, if you're in the admin group, sudo creates an empty file named .sudo_as_admin_successful in your home directory. That tells bash, the next time you log in, not to print the stupid warning any more. Sudo creates the file even if your login shell isn't bash and so you would never have seen the stupid warning. Hey, you might some day go back to bash, right?
If you want to reclaim your ls columns and get rid of the file forever, it's easy: just edit /etc/group and remove yourself from the admin group. If you were doing anything that required being in the admin group, substitute another group with a different name.
[ 18:33 Oct 09, 2008 More linux | permalink to this entry | ]