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Does it mean "user"? I attempted to navigate to usr via cd however I received No such file or directory error.

I could only find in Russian the following information:

"/usr (от англ. User System Resources — системные ресурсы пользователя) — каталог в UNIX-подобных системах, содержащий динамически компонуемые программы, файлы пользователей и программы, устанавливаемые вручную. В соответствии с FHS, монтируется на корневую файловую систему и должен содержать только не изменяющиеся программами данные (то есть /usr в режиме эксплуатации может быть смонтирован в режиме «только для чтения» без ущерба для функциональности)[1].

Традиционная система подкаталогов /usr/ Вторичная иерархия для данных пользователя; содержит большинство пользовательских приложений и утилит, используемых в многопользовательском режиме. Может быть смонтирована по сети только для чтения и быть общей для нескольких машин[2]. /usr/bin/"

However, I don't understand.

Translation of the quote:

/usr ( from English "User System Resources" ) - catalogue/directory in UNIX-like systems, containing dynamically combined programs, user files and manually-installed programs. In accordance with FHS, it is mounted on root filesystem and must contain only data which is not to be modified by programs (that is to say, /usr in operational mode can be mounted as read-only without loss of functionality)

Traditional system of subdirectories /usr/ Secondary hierarchy for user's data; contain most user's applications andutilities, used in multiuser mode. Can be mounted over network only in read-only mode, and can be shared between multiple machines.

Sergiy Kolodyazhnyy
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Anatoliy Dragan
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    What is the question? You gave the answer what usr means. – Pilot6 Feb 23 '19 at 08:56
  • I'll write an answer in English first, then translate it into Russian. So hold on there – Sergiy Kolodyazhnyy Feb 23 '19 at 09:36
  • cd /usr should not fail. Is your question about that? If so it's not a [mcve]. Or is it about what /usr is? If so it's mis-tagged. – Peter Cordes Feb 23 '19 at 18:33
  • Be explicit with commands: does "navigate to usr via cd" cd usr or cd /usr? The second may, or may not do the same than the first. Depends on the current directory. – Volker Siegel Feb 24 '19 at 02:32
  • Thank you to everybody. Sure that after I ask question - what I m so foolish and begin once and once more search. Ubuntu Linux is for me very new and difficult. + I'm 70... I read your answer more and more - from first time it does not come to my head – Anatoliy Dragan Mar 02 '19 at 20:15

3 Answers3

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/usr nowadays stands for User System Resources. This directory contains most commands and executables files, libraries and documentation. In the early days of Unix, it was the directory where the users' home directories were placed (your user home directory would have been /usr/anatoly which now is /home/anatoly), so originally it stood for User.

See Chapter 1. Linux Filesystem Hierarchy for details.

heiflo
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    Change suggestion: 'stands for Unix System Resources.' => 'stands for Unix System Resources or as it is called sometimes as well Universal System Resources.' – Videonauth Feb 23 '19 at 09:11
  • Thanks for suggesting the edit. According to The Linux Documentation Project 'usr' stands for 'User System Resources', so I changed the definition. – heiflo Feb 23 '19 at 10:37
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    Who says it stands for (or originally stood for) "User System Resources"? Seems more likely that it's a back formation, and usr was originally just a way of saving a letter or two, in the same way that bin is short for binary (and a pun :-)) mv for move, cp for copy, &c. – jamesqf Feb 23 '19 at 18:47
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    Yes, this will be a backronym. usr wasn't spelled user because back in those days all communication with the computer was via teletypes, which were hell on fingers, and by punch cards, which is why virtually everything is so abbreviated. – Michael Hampton Feb 23 '19 at 20:43
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As has been explained in the quote in the question, /usr directory stands for User System Resources. According to Debian documentation this includes applications which are not mandatory for the system to boot, and shared data (for instance /usr/share/applications holds .desktop files which are sort of shortcuts to actual application executable).

Note that the quote mentions the /usr directory should be read-only and not modifiable by programs, which applies to /usr/lib because it contains shared libraries which are critical for proper functionality of applications. However, some content such as /usr/share/applications directory contains resources that are not system critical, and can be modified by admin-level user when necessary.

Как было указано в цитате которая приложена к вопросу， каталог (или директория) /usr имеет значение User System Resources — системные ресурсы пользователя. Согласно Debian документации это влючает программы которые не обязательны для загрузки системы и общие данные (к примеру, /usr/share/applications держит ссылки к программам). Важно заметить что в цитате сказано этот каталог должен быть смонтироват для чтения, что относится к таким под-каталогам как /usr/lib поскольку этот каталог включает общие библиотеки используемые многими программами что делает их критически важными. Но такие каталоги как /usr/share/applications не содержат системно-важных ресурсов и могут изменятся при необходимости административным пользователем.

Sergiy Kolodyazhnyy
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Thre is a /usr directory on Linux systems, used to hold resources used by everybody (typically all you applications are in /usr/bin, /usr/lib, and /usr/share).

This directory is readable by all but only privileged users can write in it, which is rarely neededanyway since most files in /usr in managed by package managers (the apt... family, in Ubuntu).

xenoid
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