If you run `hash` it shows the path of all commands run since the hash was last reset (`hash -r`)

```
[root@c04c ~]# hash
hash: hash table empty

[root@c04c ~]# whoami
root

[root@c04c ~]# hash
hits    command
   1    /usr/bin/whoami

[root@c04c ~]# whoami
root

[root@c04c ~]# hash
hits    command
   2    /usr/bin/whoami

```

According to the man pages, the purpose of hash is: 

> 
> The /usr/bin/hash utility affects the way the current shell
>  environment remembers the locations of utilities found.
>  Depending on the arguments specified, it adds utility locations
>  to its list of remembered locations or it purges the
>  contents of the list. When no arguments are specified, it
>  reports on the contents of the list. The `-r` option causes
>  the shell to forget all remembered locations.
> 
> 
> Utilities provided as built-ins to the shell are not
>  reported by hash.
> 
> 
> 

*Other than seeing how many times I've entered a command, I can't see the utility of `hash`.*

It was even featured in thegeekstuff.com's [top 15 useful commands](http://www.thegeekstuff.com/2010/08/bash-shell-builtin-commands/)

**In what ways is `hash` useful?**