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Author: Ville-Matias Heikkila <viznut@low.fi>
Date: Wed, 22 Jun 2022 13:40:59 +0300
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+**Unix** is a multi-user operating system whose development was started in
+1969 by Ken Thompson and Dennis Ritchie, as well as an entire family of
+operating system derived from the original Unix. Since Unix is also a
+trademark that only applies to specific products, terms like "*nix" are
+often used to refer to the entire family of Unix-compatible systems
+(including [[GNU]]/[[Linux]]). In this article, we don't bother to respect
+the trademark (Linux is a Unix for us).
+
+Unix was originally a mainframe-like [[time-sharing]] operating system
+[[scalability|scaled down]] to much smaller computers with much more limited
+processing power and storage space. In order to keep the system small,
+elegant and flexible, it was decided to have a set of "small and sharp"
+tools that can interoperate with each other via input/output piping. At
+later times, Unix gathered bloat, and from the 1980s microcomputer point of
+view it was already seen as a huge and complex OS for big computers.
+
+The possibility to reimplement the system gradually, one tool at a time, was
+a major reason why Unix was chosen as the basis of the [[GNU]] project, even
+though [[Stallman|Richard Stallman]] didn't particularly like it.
+
+Historically, it may be interesting to compare Unix with [[Forth]] that was
+born at the same time for a somewhat similar purpose (bringing a
+"mainframe-grade" environment to a small computer), although Forth is a
+memory-oriented single-user system whereas Unix is a disk-oriented
+multi-user system. A major difference is that while Unix adopted a lot of
+ideas and principles from the mainframe world, Forth actively questioned
+them in order to get as small as possible. Also, Forth is a programming
+language to the core, while Unix consists of many separate tools that
+sometimes have a programming language built in.
+
+Advantages of Unix from the permacomputing perspective
+------------------------------------------------------
+
+ * The basic idea of having small, flexible and interoperable tools is
+ close to permacomputing ideals.
+ * The use of a high-level language ([[C]]) has made it independent from
+ specific processor and computer architectures. Programs tend to be
+ source-code-compatible across Unix systems and often even with non-Unix
+ systems.
+ * There are several independent but largely compatible implementations
+ (classical Unix, [[GNU]]/[[Linux]], [[Minix]] ...), many of which are
+ [[FLOSS]].
+ * Unix-like systems may have relatively low hardware requirements,
+ especially when talking about "barebones" systems mainly used with
+ [[character terminal]]s.
+ * Long history of use in a vast variety of different types of devices
+ (embedded, workstation, server, supercomputer, etc.).
+
+Disadvantages and problems
+--------------------------
+
+ * Modern, "real-world" Unix systems, like most general-purpose operating
+ systems, suffer from a lot of [[bloat]] and unnecessary complexity.
+ * A lot of this complexity are somehow related to legacy compatibility as
+ are many weird quirks one can find in Unix system. One might say that
+ this has resulted from an excessive prioritization of accumulated
+ tradition over system-level refactoring.
+ * Unix has reached such a dominant position in many areas of computing
+ that it represents [[monoculture]] that narrows down [[technological
+ diversity]].
+ * Despite having a long legacy, Unix is far from a [[bedrock platform]].
+ Software often needs to be constantly maintained in order to keep it
+ compatible with various libraries and other changing pieces of the
+ environment.
+ * Binary compatibility between different versions of the same OS may be
+ surprisingly bad; even C libraries (such as [[glibc|GNU]]) may change
+ their ABIs in ways that cause incompatibilities and force recompilation.
+ * Inefficiencies and limitations that can be traced back to the pre-Unix
+ mainframe ideals:
+ * Preference for sequences of plain-text lines in input and output (as
+ in 80-column IBM punched cards). Translating between plain-text
+ formats and various internal representations causes overhead.
+ * There are good tools for defining a task (by writing a command line)
+ but the chances to affect the running of the task are much more
+ limited (as in the old batch-job culture). Possibilities of building
+ interoperability between running programs are much weaker than between
+ not-yet-running programs.
+ * "Waterfall model" in software compilation, producing static monoliths
+ that are very difficult to arbitrarily change especially when they are
+ running. This has resulted in a plethora of scripting/configuration
+ languages that compensate for the inflexibility.
+ * The original Unix shell was designed to be quite minimal, and
+ programmability was added to it in various ad-hoc ways by later
+ developers. Various scripting languages have come into use as a response
+ to the messiness of shell scripting.
+
+Unix-like operating systems and kernels
+---------------------------------------
+
+ * [[BSD]]
+ * [[Minix]]
+ * [[GNU]]
+ * [[Linux]]
+ * [[Darwin]]
+ * [[Plan9]]
