https://help.ubuntu.com/lts/serverguide/user-management.html

Logid
https://help.ubuntu.com/community/LinuxLogFiles
http://www.cyberciti.biz/faq/ubuntu-linux-gnome-system-log-viewer/

tail -f /var/log/auth.log
more /var/log/auth.log
cat /var/log/auth.log
less /var/log/auth.log
grep -i fail /var/log/auth.log
(-i ignore the case; man grep)

File access
http://askubuntu.com/questions/647914/how-can-i-log-file-access-from-users
iwatch - iwatch.sourceforge.net/documentation.html