[jmclnx]

Maybe in sh type shells. In csh/tcsh commands are hashed, so command completion is in memory. Thus the need for rehash.

There is a new setting in tcsh to allow for automatic rehash, but I have it disabled.

[mst]

hash -r in bash. No idea if there's a setting, I'm too used to doing the rehash as required to've noticed if there was.