Ok, some history...

back in the day ... when drives were smaller ;-)

/bin was mounted on the "root" partition
/usr was probably on another partition or disk.

Thus, you needed to have all the programs required to at least get to 
mounting another filesystem in the /bin folder.
Once the /usr was mounted, it did not matter where the files were.

Another motivation for the seperate /usr mount point was that often, for 
a number of reasons, the root filesystem was mounted as a read-only 
filesystem... (you could never corrupt your core OS, and you could never 
fill your root file-system, thus saving very embarrasing crashes....)

/sbin, as others have sais, is (normally)_ only accessible to the root 
user, and are not programs runnable by regular users. Required only to 
boot the machine.
/usr/sbin ... follows the same mount point logic as /usr/bin.

The standard is/was, that "official" programs went in to the /bin or 
/usr/bin area, but locally compiled code went in to /usr/local/bin.
This is for a few reasons, but the primary one being that you can put 
/usr/local/bin in front of /usr/bin in your $PATH, and thus, you can 
"override" the default programs. This is especially useful with 
"package" type installation mechanisms like solaris (with pkg), AIX with 
it's own package installers, Linux with RPM, or deb, etc. Thus, the 
"package" will install in to /usr/bin, and you can "extend or override" 
the program in /usr/local/bin. The biggest benefit of this is that an 
upgrade to the package will not delete your "upgrade".

Additionally, most users should have a $HOME/bin, which should be at the 
front of the $PATH, making it override anything else.

Rolf

John Nall wrote:

> On Wed, 2005-10-19 at 15:19 -0700, Harold Hallikainen wrote:
>
>>>> I'm still trying to figure out the meaning of all the directories in
>>>
>>> linux. bin makes sense for binaries... What's /usr mean? and 
>>> /usr/local?
>>> I'm thinking sbin is binaries for the superuser or root, right? Of 
>>> course,
>>> all the configs end up in /etc instead of in the directory where the
>>> application is... And they log stuff to /var/log . So... stuff's 
>>> scattered
>>> somewhat. But what's the difference between /usr/local and /usr?
>>>   
>>
>
> A lot of that stuff is just historical (Unix background) and to some 
> degree defies any rational explanation.  ("We do it  that way because 
> it has always been done that way!")..  :-)  I feel sure that if you 
> can just manage to phrase a question to Google correctly, that you 
> will get an explanation of each and every directory..  But of course 
> formulating the correct question is easier said than done.  On the 
> other hand, though, it does make SOME sense, whereas Windoze makes no 
> sense at all.  IMHO.  Once you get beyond "My Documents" you are in 
> Indian country.
>
> John
>


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