/usr/, I assume is the drug user of the computer .

close .
Unix started out as a multi-user operational arrangement, so it ‘s not “ the drug user, ” it ‘s “ the users, ” plural .
Before AT & T Unix System V Release 4 ( SVR4 ) came out in 1988 with its user management tools defaulting to creating drug user home directories in /home, the ceremonious location was /usr .¹ Your $HOME directory might have been /usr/jfw on a System III box.

/usr besides contained, then as now, /usr/bin, /usr/lib, etc. know showed that segregating the home directories was well system management practice, sol with the /home policy change in SVR4, it left behind everything we immediately think of as belong in /usr .
/usr still had a good reason to hold onto the name : what got left behind were files that did n’t need to be available until the system was booted up far adequate to support normal interactional manipulation. That is to say, what was left behind were the user-focused parts of the OS. This think of that /usr could be on a different physical volume, which was a dependable thing back in the days of 92 MB hard phonograph record drives the size of washing machines .
early Unix systems were careful to keep the core OS files out of /usr so that you could still boot into single-user mode² even if the /usr volume was unmountable for some reason. The root bulk contained sufficient tools to get the /usr volume back on-line .
respective Unix flavors now disregard this old design principle since even small embedded systems have enough room for both the traditional etymon volume files and all of /usr on a single volume.³ Red Hat Enterprise Linux, Solaris and Cygwin symlink /bin to /usr/bin and /lib to /usr/lib so that there is no longer any difference between these directories .

… /local/ … obviously stands for the local anesthetic computer …

Yes. It refers to the fact that files under /usr/local are supposed to be finical to that individual arrangement. Files that are in any way generic should live elsewhere .
This besides has roots in the direction Unix systems were normally used decades ago when all this was standardized. Again, unvoiced disks of the time were bulky, truly expensive, and stored little by nowadays ‘s standards. To save money and space on disks, a computer lab full of Unix boxes would much share most of /usr over NFS or some other network file sharing protocol, so each box did n’t have to have its own excess copy.⁴ Files specific to a single corner would go under /usr/local, which would be a branch volume from /usr .
This historical inheritance is why it ‘s still the default for most third-party Unix software to install into /usr/local when installed by hand. Most such software will let you install the box somewhere else, but by making a non-choice, you get the safe nonpayment, which does n’t interfere with other coarse install locations with more particular purposes .
There are good reasons to make software install somewhere else alternatively. Apple ‘s macOS team does this when they build, say, bash from the GNU Bash source code. They use / as the facility prefix, overriding the /usr/local default, so that Bash ends up in /bin .
Another exercise is the way older Linux systems segregated their GUI software into /usr/X11R6, to keep it freestanding from the traditional command wrinkle and curses -based software. This was done plainly by overriding the nonpayment /usr/local prefix with /usr/X11R6 .⁵

And what is /bin ?

It ‘s light for “ binary star, ” which in this context means “ a file that is not plain textbook. ” Most such files are executables on a Unix box, so these two terms have become synonymous in some circles. ( “ Please build me a binary for RHEL 7, Fred. ” )
Text files on a Unix box live elsewhere : /etc, /usr/include, /usr/share, etc.

once upon a time, even shell scripts — which are plain text files — were kept out of bin directories, but this line, excessively, has blurred. today, bin directories typically hold any kind of feasible file, whether rigorously “ binary ” or not.⁶
Footnotes and Digressions :

  1. The archaic nature of the user management tools anterior to SVR4 entail that the HOME=/usr/$NAME system was merely documented as a conventionality, rather than enforced by software tools as a default .
    You can see this on page 4-8 of the “ AT & T Unix System V Release 3.2 System Administrator ‘s Guide : here you see AT & T recommending the old /usr/$NAME system in the last major version of Unix before SVR4 came out .
    It was reasonably common in older Unix systems for the system administrators to choose a unlike dodge that made more sense to them. People being people, that meant a bunch of different schemes got invented .
    One schema I came across before /home/$NAME became the standard was /u/$NAME .
    Another system I used in the early 1990s had so many users that they could n’t fit all the home directories onto a single physical bulk, so they used a system like /u1/$NAME, /u2/$NAME, and so on, as I recall. Which disk your home directory ended up on was just a matter of which one had space on it at the clock time your history was created .
  2. You can boot a macOS box into single-user modality by holding down Cmd-S while it boots. Let go once the screen turns bootleg and you see light up grey text look. It ‘s like running under the Terminal, but it takes over the unharmed sieve because the GUI has n’t started even .
    Be careful, you ‘re running as root .
    type “ die ” at the single-user root prompt to leave single-user manner and continue booting into multi-user GUI mode .
  3. Unixy OSes that still appear to keep critical single-user modality files out of /usr may not, in fact, do so these days. I once rendered a FreeBSD 9 box unbootable by moving /usr to a ZFS volume. I forgot that the ZFS-on-root features did n’t land until FreeBSD 10, creating a catch 22 : the OS needed files in /usr in ordain to mount /usr !
    That was badly enough, but if FreeBSD 9 were even keeping its single-user bang stuff out of /usr, I could have fixed it in place. Since it would n’t boot even to single-user modality with /usr being unmountable, intelligibly that tradition had been violated somehow. I had to boot from a rescue cadmium to get that system back up again.

  4. This is besides where we get /usr/share : it segregates files that could be shared ( e.g. over NFS ) even between Unix boxes with unlike central processing unit types. typically, textbook files : man pages, the dictionary, etc .
  5. “ X11R6 ” referred to the version of the X Window System underpinning Linux GUIs at the time this convention was prevailing. Linux systems broadly stopped segregating the GUI software about the clock X11R6 was replaced with X.Org .
  6. The original Unix systems kept their congress of racial equality carapace scripts in /etc in ordering to avoid commingling them with the true binaries in /bin .

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