It seems that some IT departments like to lock out the fast user switching option on company laptops in a lot of companies at the moment. This became a problem for me as I have a local admin account on my work machine, and I have to switch to it whenever I want to install from a dmg file. This got me thinking, is there a command line argument or tool that I could run to do this? Sure enough there is. The only thing you need to look up is the UserId for the user that you want to switch to.
Clearing the cache on Mac’s seems to change with every other release these days. In all cases though you need to use Terminal, but not always the same command. Back in the 10.4 days you would use lookupd, then in 10.5 and 10.6 you would use dscacheutil, but now in 10.7 you need to now use a killall command.