Gregory's Server
@Luisa_Donato It doesn't! To quote "The UNIX Programming Environment" (https://archive.org/details/UnixProgrammingEnviornment) by BWK and Rob Pike:
> _(user is abbreviated to usr in the same spirit as cmp, Is, etc.) /usr/you is your login directory, your current directory when you first log in._
(p. 48)
and
> _/usr is called the “user file system,” although it may have little to do with the actual users of the system. On our machine, our login directories are /usr/bwk and /usr/rob, but on your machine the /usr part might be dif ferent,[...]_
(p. 65)
There's another interesting paragraph following it:
> _Just as in /, there are directories called /usr/bin, /usr/lib and /usr/tmp. These directories have functions similar to their namesakes in /, but contain programs less critical to the system. For example, nroff is usually in /usr/bin rather than /bin, and the FORTRAN compiler libraries live in /usr/lib. Of course, just what is deemed “critical” varies from system to system. Some systems, such as the
distributed 7th Edition, have all the programs in /bin and do away with /usr/bin altogether; others split /usr/bin into two directories according to frequency of use. _
@Luisa_Donato
To give a bit of history: The user file system`/usr` was indeed used for home directories but on a separate disk, namely `/dev/rp01`, while the rest of the *root* file system resided on `/dev/rp00`. The latter was a faster and smaller disk which contained the system, the second disk was added once it was full and the user home directories moved to it. In UNIX V3, there were too many binaries in `/bin` to store on the fast disk, less crucial binaries were stored in a special "user directory" for those binaries, called `/usr/bin` (also, some of them where simply stored in the developer's directory, so you had a bunch of `/usr/dmr/ls` or the like. This practice of splitting crucial from non-curcial binaries, only born out of disk space got standardized. On most modern UNIX and alike systems, the initial boot happens through something like Linux' initial RAM file system, thus completely removing the need for having "crucial" binaries separate. Which is why most Linux distros move or moved to merge everything (for some reason they merged it into `/usr` instead of getting rid of it, like UNIX V7 from '79, don't ask me why). At some point people startet calling it "UNIX System Resources" as a "post hoc backronym".
Also cf. DMR's "UNIX Notes" https://www.bell-labs.com/usr/dmr/www/notes.html
@Luisa_Donato
To give a bit of history: The user file system`/usr` was indeed used for home directories but on a separate disk, namely `/dev/rp01`, while the rest of the *root* file system resided on `/dev/rp00`. The latter was a faster and smaller disk which contained the system, the second disk was added once it was full and the user home directories moved to it. In UNIX V3, there were too many binaries in `/bin` to store on the fast disk, less crucial binaries were stored in a special "user directory"...