hash

hash [-r] [commands]

Bourne shell version. Search for commands and remember the directory in which each command resides. Before a new shell program has been hashed, it can be executed only from the directory in which it was created. Hashing a command allows it to be run from any directory. (Hashing a command adds it to a list of commands "known" to the shell.) Commands must also be hashed if you change your PATH variable. - removes commands from the hash list, either all of them or just the specified commands. With no arguments, hash lists the current hashed commands. The display shows hits (the number of times the command is called by the shell) and cost (the level of work needed to find the command).