rehash - recompute the path hash table
rehash
This command is a C-shell built-in command.
The rehash(1) command causes the internal hash table of the contents of the directories in the path variable to be recomputed. This is needed if new commands are added to directories in path while you are logged on. This should only be necessary if you add commands to one of your own directories, or if a systems programmer changes the contents of one of the system directories. The rehash command also flushes the cache of home directories built by tilde (~)expansion.