I can see that there are these 2 commands in the pdf
rm -f /etc/profile
cp -f /Database/profile /etc
from what I can read on the pdf, the guy who wrote it, forgot to copy the /etc/profile to /Database/profile. By the time you reboot, the profile was erased and there was no /Database/profile to copy it back.
That is how you accidentally erased it 😛