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81-477: Make is widely used, especially in Unix and Unix-like operating systems , even though many competing technologies and tools are available including: similar tools that perform actions based on dependencies, some compilers and interactively via an integrated development environment . In addition to referring to the original Unix tool, Make is also a technology since multiple tools have been implemented with roughly

162-471: A PROMPT $ N:$ W$ G would instead yield C:DOS> and C:DRDOS> , respectively. A similar facility (using $ W and $ w ) was added to 4DOS as well. Under DOS, the absolute paths of the working directories of all logical volumes are internally stored in an array-like data structure called the Current Directory Structure (CDS), which gets dynamically allocated at boot time to hold

243-488: A DOS emulation on top of a Concurrent DOS - (and thus CP/M-86 -)derived kernel, which internally organized subdirectories as relative links to parent directories instead of as absolute paths. Since PalmDOS (with BDOS 7.0) and DR DOS 6.0 (1992 update with BDOS 7.1) and higher switched to use a CDS for maximum compatibility with DOS programs as well, they faced the same limitations as present in other DOSes. Most programming languages provide an interface to

324-429: A time-sharing configuration, as well as portability. Unix systems are characterized by various concepts: the use of plain text for storing data; a hierarchical file system ; treating devices and certain types of inter-process communication (IPC) as files; and the use of a large number of software tools , small programs that can be strung together through a command-line interpreter using pipes , as opposed to using

405-481: A time-sharing operating system for the GE 645 mainframe computer. Multics featured several innovations , but also presented severe problems. Frustrated by the size and complexity of Multics, but not by its goals, individual researchers at Bell Labs started withdrawing from the project. The last to leave were Ken Thompson , Dennis Ritchie , Douglas McIlroy , and Joe Ossanna , who decided to reimplement their experiences in

486-511: A 1999 interview, Dennis Ritchie voiced his opinion that Linux and BSD Unix operating systems are a continuation of the basis of the Unix design and are derivatives of Unix: I think the Linux phenomenon is quite delightful, because it draws so strongly on the basis that Unix provided. Linux seems to be among the healthiest of the direct Unix derivatives, though there are also the various BSD systems as well as

567-460: A convenient platform for programmers developing software to be run on it and on other systems, rather than for non-programmers. The system grew larger as the operating system started spreading in academic circles, and as users added their own tools to the system and shared them with colleagues. At first, Unix was not designed to support multi-tasking or to be portable . Later, Unix gradually gained multi-tasking and multi-user capabilities in

648-455: A dependency analyzer, boiled down to something much simpler, and turned into Make that weekend. Use of tools that were still wet was part of the culture. Makefiles were text files, not magically encoded binaries, because that was the Unix ethos : printable, debuggable, understandable stuff. Before Make, building on Unix mostly consisted of shell scripts written for each program's codebase. Make's dependency ordering and out-of-date checking makes

729-452: A generic term such as system to help avoid the creation of a genericized trademark . Working directory In computing , the working directory of a process is a directory of a hierarchical file system , if any, dynamically associated with the process. It is sometimes called the current working directory (CWD) , e.g. the BSD getcwd function, or just current directory . When

810-427: A makefile, Make updates target files from source files if any source file has a newer timestamp than the target file or the target file does not exist. For example, this could include compiling C files ( *.c ) into object files , then linking the object files into an executable program. Or this could include compiling TypeScript files ( *.ts ) to JavaScript for use in a browser. Other examples include: convert

891-405: A new project of smaller scale. This new operating system was initially without organizational backing, and also without a name. The new operating system was a single-tasking system. In 1970, the group coined the name Unics for Uniplexed Information and Computing Service as a pun on Multics , which stood for Multiplexed Information and Computer Services . Brian Kernighan takes credit for

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972-422: A parameter /B (for "Batch"). This modifies the output of commands to become suitable for direct command line input (when redirecting it into a batch file) or usage as a parameter for other commands (using it as input for another command). Where CHDIR would issue a directory path like C:\DOS , a command like CHDIR /B would issue CHDIR C:\DOS instead, so that CHDIR /B > RETDIR.BAT would create

1053-507: A potential universal operating system, suitable for computers of all sizes. The Unix environment and the client–server program model were essential elements in the development of the Internet and the reshaping of computing as centered in networks rather than in individual computers. Both Unix and the C programming language were developed by AT&T and distributed to government and academic institutions, which led to both being ported to

1134-489: A process refers to a file using a simple file name or relative path (as opposed to a file designated by a full path from a root directory ), the reference is interpreted relative to the working directory of the process. So for example a process with working directory /rabbit-shoes that asks to create the file foo.txt will end up creating the file /rabbit-shoes/foo.txt . In most computer file systems, every directory has an entry (usually named " . ") which points to

1215-412: A recipe is optional, the dependency line can consist solely of components that refer to other targets, for example: The following example rule is evaluated when Make updates target file.txt; i.e. via make file.txt . If file.html is newer than file.txt or file.txt does not exist, then the command is run to generate file.txt from file.html. A command can have one or more of the following prefixes (after

1296-420: A reference directory layout for Unix-like operating systems; it has mainly been used in Linux. The Unix system is composed of several components that were originally packaged together. By including the development environment, libraries, documents and the portable, modifiable source code for all of these components, in addition to the kernel of an operating system, Unix was a self-contained software system. This

1377-498: A representation like Un*x , *NIX , or *N?X is used to indicate all operating systems similar to Unix. This comes from the use of the asterisk ( * ) and the question mark characters as wildcard indicators in many utilities. This notation is also used to describe other Unix-like systems that have not met the requirements for UNIX branding from the Open Group. The Open Group requests that UNIX always be used as an adjective followed by

1458-399: A set of cultural norms for developing software, norms which became as important and influential as the technology of Unix itself; this has been termed the Unix philosophy . The TCP/IP networking protocols were quickly implemented on the Unix versions widely used on relatively inexpensive computers, which contributed to the Internet explosion of worldwide, real-time connectivity and formed

1539-474: A single monolithic program that includes all of the same functionality. These concepts are collectively known as the " Unix philosophy ". Brian Kernighan and Rob Pike summarize this in The Unix Programming Environment as "the idea that the power of a system comes more from the relationships among programs than from the programs themselves". By the early 1980s, users began seeing Unix as

1620-541: A single nine-track magnetic tape , earning its reputation as a portable system. The printed documentation, typeset from the online sources, was contained in two volumes. The names and filesystem locations of the Unix components have changed substantially across the history of the system. Nonetheless, the V7 implementation has the canonical early structure: The Unix system had a significant impact on other operating systems. It achieved its reputation by its interactivity, by providing

1701-406: A source image file to another format, copy a file to a content management system, and send e-mail about build status. A makefile defines targets where each is either a file to generate or is a user-defined concept, called a phony target. Make updates the targets passed as arguments: If no target is specified, Make updates the first target in the makefile which is often a phony target to perform

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1782-571: A temporary batchjob allowing to return to this directory later on. The working directory is also displayed by the $ P token of the PROMPT command To keep the prompt short even inside of deep subdirectory structures, the DR-DOS 7.07 COMMAND.COM supports a $ W token to display only the deepest subdirectory level. So, where a default PROMPT $ P$ G would result f.e. in C:\DOS>; or C:\DOS\DRDOS> ,

1863-479: A uniform interface, but at the expense of occasionally requiring additional mechanisms such as ioctl and mode flags to access features of the hardware that did not fit the simple "stream of bytes" model. The Plan 9 operating system pushed this model even further and eliminated the need for additional mechanisms. Unix also popularized the hierarchical file system with arbitrarily nested subdirectories, originally introduced by Multics. Other common operating systems of

1944-498: A versatile document preparation system, and an efficient file system featuring sophisticated access control, mountable and de-mountable volumes, and a unified treatment of peripherals as special files ." The latter permitted the Network Control Program (NCP) to be integrated within the Unix file system, treating network connections as special files that could be accessed through standard Unix I/O calls , which included

2025-478: A visit from Steve Johnson (author of yacc, etc.), storming into my office, cursing the Fates that had caused him to waste a morning debugging a correct program (bug had been fixed, file hadn't been compiled, cc *.o was therefore unaffected). As I had spent a part of the previous evening coping with the same disaster on a project I was working on, the idea of a tool to solve it came up. It began with an elaborate idea of

2106-402: A wider variety of machine families than any other operating system. The Unix operating system consists of many libraries and utilities along with the master control program, the kernel . The kernel provides services to start and stop programs, handles the file system and other common "low-level" tasks that most programs share, and schedules access to avoid conflicts when programs try to access

2187-400: Is expanded on each use ( lazily ). A macro is used by expanding either via $ NAME or $ ( NAME ). The latter is safer since omitting the parentheses leads to Make interpreting the next letter after the $ as the entire variable name. An equivalent form uses curly braces rather than parentheses, i.e. $ {} , which is the style used in BSD . Macros can be composed of shell commands by using

2268-589: Is history. GNU Make. since version 3.82, allows the choice of any symbol (one character) as the recipe prefix using the .RECIPEPREFIX special variable, for example: Each command is executed in a separate shell . Since operating systems use different shells this can lead to unportable makefiles. For example, GNU Make (all POSIX Makes) executes commands with /bin/sh by default, where Unix commands like cp are normally used. In contrast to that, Microsoft's nmake executes commands with cmd.exe where batch commands like copy are available but not necessarily cp. Since

2349-433: Is not synchronized with the machine running Make. Also, if a source file's timestamp is in the future, make repeatedly triggers unnecessary actions, causing longer build time. When Make starts, it uses the makefile specified on the command-line or if not specified, then uses the one found by via specific search rules. Generally, Make defaults to using the file in the working directory named Makefile . GNU Make searches for

2430-461: Is subject to criticism; described by Eric S. Raymond as "one of the worst design botches in the history of Unix" and The Unix-Haters Handbook said "using tabs as part of the syntax is like one of those pungee stick traps in The Green Berets ". Feldman explains the choice as caused by a workaround for an early implementation difficulty preserved by a desire for backward compatibility with

2511-598: The Bell Labs research center by Ken Thompson , Dennis Ritchie , and others. Initially intended for use inside the Bell System , AT&T licensed Unix to outside parties in the late 1970s, leading to a variety of both academic and commercial Unix variants from vendors including University of California, Berkeley ( BSD ), Microsoft ( Xenix ), Sun Microsystems ( SunOS / Solaris ), HP / HPE ( HP-UX ), and IBM ( AIX ). Early versions of Unix ran on PDP-11 computers; Unix

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2592-761: The GNU Compiler Collection (and the rest of the GNU toolchain ), the GNU C library and the GNU Core Utilities  – have gone on to play central roles in other free Unix systems as well. Linux distributions , consisting of the Linux kernel and large collections of compatible software have become popular both with individual users and in business. Popular distributions include Red Hat Enterprise Linux , Fedora , SUSE Linux Enterprise , openSUSE , Debian , Ubuntu , Linux Mint , Slackware Linux , Arch Linux and Gentoo . A free derivative of BSD Unix, 386BSD ,

2673-578: The UNIX 98 or UNIX 03 trademarks today, after the operating system's vendor pays a substantial certification fee and annual trademark royalties to The Open Group. Systems that have been licensed to use the UNIX trademark include AIX , EulerOS , HP-UX , Inspur K-UX , IRIX , macOS , Solaris , Tru64 UNIX (formerly "Digital UNIX", or OSF/1 ), and z/OS . Notably, EulerOS and Inspur K-UX are Linux distributions certified as UNIX 03 compliant. Sometimes

2754-458: The command substitution operator, != . The command-line syntax for overriding a macro is: Makefiles can access predefined internal macros , with ? and @ being common. A common syntax when defining macros, which works on BSD and GNU Make, is to use of += , ?= , and != instead of the equal sign ( = ). Suffix rules have "targets" with names in the form .FROM.TO and are used to launch actions based on file extension. In

2835-563: The command-line arguments passed to the Make utility. Environment variables are also available as macros. For example, the macro CC is frequently used in makefiles to refer to the location of a C compiler. If used consistently throughout the makefile, then the compiler used can be changed by changing the value of the macro rather than changing each rule command that invokes the compiler. Macros are commonly named in all-caps : A macro value can consist of other macro values. The value of macro

2916-622: The file system functions of the operating system, including the ability to set (change) the working directory of the program. In the C language , the POSIX function chdir() effects the system call which changes the working directory. Its argument is a text string with a path to the new directory, either absolute or relative to the old one. Where available, it can be called by a process to set its working directory. There are similar functions in other languages. For example, in Visual Basic it

2997-475: The Open Group Base Specification. In 1999, in an effort towards compatibility, several Unix system vendors agreed on SVR4's Executable and Linkable Format (ELF) as the standard for binary and object code files. The common format allows substantial binary compatibility among different Unix systems operating on the same CPU architecture. The Filesystem Hierarchy Standard was created to provide

3078-480: The UNIX trademark to The Open Group , an industry consortium founded in 1996. The Open Group allows the use of the mark for certified operating systems that comply with the Single UNIX Specification (SUS). Unix-like operating systems have been relevant since the 1990s which function similarly to Unix: popular examples are GNU (including Linux ), FreeBSD and macOS . Unix was originally meant to be

3159-530: The ability to store the working directory. COMMAND.COM in DR-DOS 7.02 and higher provides ECHOS , a variant of the ECHO command omitting the terminating linefeed. This can be used to create a temporary batchjob storing the working directory in an environment variable like CD for later use, for example: Alternatively, under Multiuser DOS and DR-DOS 7.02 and higher, various internal and external commands support

3240-616: The added benefit of closing all connections on program exit, should the user neglect to do so. In order "to minimize the amount of code added to the basic Unix kernel ", much of the NCP code ran in a swappable user process, running only when needed. In October 1993, Novell , the company that owned the rights to the Unix System V source at the time, transferred the trademarks of Unix to the X/Open Company (now The Open Group ), and in 1995 sold

3321-465: The basis for a widely implemented operating system interface standard (POSIX, see above). The C programming language soon spread beyond Unix, and is now ubiquitous in systems and applications programming. Early Unix developers were important in bringing the concepts of modularity and reusability into software engineering practice, spawning a "software tools" movement. Over time, the leading developers of Unix (and programs that ran on it) established

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3402-435: The basis for implementations on many other platforms. The Unix policy of extensive on-line documentation and (for many years) ready access to all system source code raised programmer expectations, and contributed to the launch of the free software movement in 1983. In 1983, Richard Stallman announced the GNU (short for "GNU's Not Unix") project, an ambitious effort to create a free software Unix-like system—"free" in

3483-449: The build process more robust and more efficient. The makefile allowed for better organization of build logic and often fewer build files. Make is widely used in part due to its early inclusion in Unix , starting with PWB/UNIX 1.0, which featured a variety of software development tools. Make has been implemented numerous times, generally using the same makefile format and providing the same features, but some providing enhancements from

3564-492: The command interpreter an ordinary user-level program, with additional commands provided as separate programs, was another Multics innovation popularized by Unix. The Unix shell used the same language for interactive commands as for scripting ( shell scripts  – there was no separate job control language like IBM's JCL ). Since the shell and OS commands were "just another program", the user could choose (or even write) their own shell. New commands could be added without changing

3645-824: The command lines of suffix rules, POSIX specifies that the internal macro $ < refers to the first prerequisite and $ @ refers to the target. In this example, which converts any HTML file into text, the shell redirection token > is part of the command line whereas $ < is a macro referring to the HTML file: When called from the command line, the example above expands. Suffix rules cannot have any prerequisites of their own. If they have any, they are treated as normal files with unusual names, not as suffix rules. GNU Make supports suffix rules for compatibility with old makefiles but otherwise encourages usage of pattern rules . A pattern rule looks like an ordinary rule, except that its target contains exactly one % character within

3726-475: The core of the Mac OS X operating system, later renamed macOS . Unix-like operating systems are widely used in modern servers , workstations , and mobile devices . In the late 1980s, an open operating system standardization effort now known as POSIX provided a common baseline for all operating systems; IEEE based POSIX around the common structure of the major competing variants of the Unix system, publishing

3807-627: The directory itself. In most DOS and UNIX command shells , as well as in the Microsoft Windows command line interpreters cmd.exe and Windows PowerShell , the working directory can be changed by using the CD or CHDIR commands . In Unix shells , the pwd command outputs a full pathname of the working directory; the equivalent command in DOS and Windows is CD or CHDIR without arguments (whereas in Unix, cd used without arguments takes

3888-546: The era had ways to divide a storage device into multiple directories or sections, but they had a fixed number of levels, often only one level. Several major proprietary operating systems eventually added recursive subdirectory capabilities also patterned after Multics. DEC's RSX-11M 's "group, user" hierarchy evolved into OpenVMS directories, CP/M 's volumes evolved into MS-DOS 2.0+ subdirectories, and HP's MPE group.account hierarchy and IBM's SSP and OS/400 library systems were folded into broader POSIX file systems. Making

3969-649: The first POSIX standard in 1988. In the early 1990s, a separate but very similar effort was started by an industry consortium, the Common Open Software Environment (COSE) initiative, which eventually became the Single UNIX Specification (SUS) administered by The Open Group . Starting in 1998, the Open Group and IEEE started the Austin Group , to provide a common definition of POSIX and the Single UNIX Specification, which, by 2008, had become

4050-424: The first file matching: GNUmakefile , makefile , or Makefile . Make processes the options of the command-line based on the loaded makefile. The makefile language is partially declarative programming where end conditions are described but the order in which actions are to be taken is not. This type of programming can be confusing to programmers used to imperative programming . Makefiles can contain

4131-403: The following constructs: Each rule begins with a dependency line which consists of the rule's target name followed by a colon (:) and optionally a list of targets on which the rule's target depends, its prerequisites. Usually a rule has a single target, rather than multiple. A dependency line may be followed by a recipe; a series of TAB indented command lines which define how to generate

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4212-420: The idea, but adds that "no one can remember" the origin of the final spelling Unix . Dennis Ritchie, Doug McIlroy, and Peter G. Neumann also credit Kernighan. The operating system was originally written in assembly language , but in 1973, Version 4 Unix was rewritten in C . Version 4 Unix, however, still had much PDP-11 specific code, and was not suitable for porting. The first port to another platform

4293-476: The late 1970s and early 1980s, the influence of Unix in academic circles led to large-scale adoption of Unix ( BSD and System V ) by commercial startups, which in turn led to Unix fragmenting into multiple, similar — but often slightly and mutually incompatible — systems including DYNIX , HP-UX , SunOS / Solaris , AIX , and Xenix . In the late 1980s, AT&T Unix System Laboratories and Sun Microsystems developed System V Release 4 ( SVR4 ), which

4374-428: The modular design of the Unix model, sharing components is relatively common: most or all Unix and Unix-like systems include at least some BSD code, while some include GNU utilities in their distributions. Linux and BSD Unix are increasingly filling market needs traditionally served by proprietary Unix operating systems, expanding into new markets such as the consumer desktop , mobile devices and embedded devices . In

4455-443: The more official offerings from the workstation and mainframe manufacturers. In the same interview, he states that he views both Unix and Linux as "the continuation of ideas that were started by Ken and me and many others, many years ago". OpenSolaris was the free software counterpart to Solaris developed by Sun Microsystems , which included a CDDL -licensed kernel and a primarily GNU userland. However, Oracle discontinued

4536-423: The most commonly used action. Make skips build actions if the target file timestamp is after that of the source files. Doing so optimizes the build process by skipping actions when the target file is up-to-date, but sometimes updates are skipped erroneously due to file timestamp issues including restoring an older version of a source file, or when a network filesystem is a source of files and its clock or time zone

4617-420: The necessary number of slots for all logical drives (or as defined by LASTDRIVE ). This structure imposes a length-limit of 66 characters on the full path of each working directory, and thus implicitly also limits the maximum possible depth of subdirectories. DOS Plus and older issues of DR DOS (up to DR DOS 6.0 , with BDOS 6.7 in 1991) had no such limitation due to their implementation using

4698-486: The networks and creating the Internet: Commercialization, privatization, broader access leads to the modern Internet: Examples of Internet services: Unix ( / ˈ j uː n ɪ k s / , YOO -niks ; trademarked as UNIX ) is a family of multitasking , multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at

4779-475: The operating system should provide a set of simple tools, each of which performs a limited, well-defined function. A unified and inode -based filesystem and an inter-process communication mechanism known as " pipes " serve as the main means of communication, and a shell scripting and command language (the Unix shell ) is used to combine the tools to perform complex workflows. In the early 1990s, AT&T sold its rights in Unix to Novell , which then sold

4860-500: The original version of Unix – the entire system was configured using textual shell command scripts. The common denominator in the I/O system was the byte – unlike "record-based" file systems . The focus on text for representing nearly everything made Unix pipes especially useful and encouraged the development of simple, general tools that could easily be combined to perform more complicated ad hoc tasks. The focus on text and bytes made

4941-575: The original. Examples: POSIX includes standardization of the basic features and operation of the Make utility, and is implemented with varying degrees of compatibility with Unix-based versions of Make. In general, simple makefiles may be used between various versions of Make with reasonable success. GNU Make, Makepp and some versions of BSD Make default to looking first for files named "GNUmakefile", "Makeppfile" and "BSDmakefile" respectively, which allows one to put makefiles which use implementation-defined behavior in separate locations. In general, based on

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5022-583: The project upon their acquisition of Sun, which prompted a group of former Sun employees and members of the OpenSolaris community to fork OpenSolaris into the illumos kernel. As of 2014, illumos remains the only active, open-source System V derivative. In May 1975, RFC 681 described the development of Network Unix by the Center for Advanced Computation at the University of Illinois Urbana-Champaign . The Unix system

5103-575: The related business operations to Santa Cruz Operation (SCO). Whether Novell also sold the copyrights to the actual software was the subject of a federal lawsuit in 2006, SCO v. Novell , which Novell won. The case was appealed, but on August 30, 2011, the United States Court of Appeals for the Tenth Circuit affirmed the trial decisions, closing the case. Unix vendor SCO Group Inc. accused Novell of slander of title . The present owner of

5184-448: The same functionality – including similar makefile syntax and semantics . Stuart Feldman created Make while at Bell Labs . An early version was completed in April 1976. Feldman received the 2003 ACM Software System Award for authoring Make. Feldman describes the inspiration to write Make came from a coworker's frustration with the available tooling of the time: Make originated with

5265-472: The same resource or device simultaneously. To mediate such access, the kernel has special rights, reflected in the distinction of kernel space from user space , the latter being a lower priority realm where most application programs operate. The origins of Unix date back to the mid-1960s when the Massachusetts Institute of Technology , Bell Labs , and General Electric were developing Multics ,

5346-520: The sense that everyone who received a copy would be free to use, study, modify, and redistribute it. The GNU project's own kernel development project, GNU Hurd , had not yet produced a working kernel, but in 1991 Linus Torvalds released the Linux kernel as free software under the GNU General Public License . In addition to their use in the GNU operating system, many GNU packages – such as

5427-427: The shell itself. Unix's innovative command-line syntax for creating modular chains of producer-consumer processes ( pipelines ) made a powerful programming paradigm ( coroutines ) widely available. Many later command-line interpreters have been inspired by the Unix shell. A fundamental simplifying assumption of Unix was its focus on newline - delimited text for nearly all file formats. There were no "binary" editors in

5508-654: The software at a nominal fee for educational use, by running on inexpensive hardware, and by being easy to adapt and move to different machines. Unix was originally written in assembly language , but was soon rewritten in C , a high-level programming language . Although this followed the lead of CTSS , Multics and Burroughs MCP , it was Unix that popularized the idea. Unix had a drastically simplified file model compared to many contemporary operating systems: treating all kinds of files as simple byte arrays. The file system hierarchy contained machine services and devices (such as printers , terminals , or disk drives ), providing

5589-560: The string. The target is considered a pattern for matching file names: the % can match any substring of zero or more characters, while other characters match only themselves. The prerequisites likewise use % to show how their names relate to the target name. The example above of a suffix rule would look like the following pattern rule: Single-line comments are started with the hash symbol (#). A directive specifies special behavior such as including another makefile. Unix Early research and development: Merging

5670-418: The system far more scalable and portable than other systems. Over time, text-based applications have also proven popular in application areas, such as printing languages ( PostScript , ODF ), and at the application layer of the Internet protocols , e.g., FTP , SMTP , HTTP , SOAP , and SIP . Unix popularized a syntax for regular expressions that found widespread use. The Unix programming interface became

5751-444: The tab): Ignoring errors and silencing echo can alternatively be obtained via the special targets .IGNORE and .SILENT . Microsoft's NMAKE has predefined rules that can be omitted from these makefiles, e.g. c.obj $ ( CC )$ ( CFLAGS ) . A makefile can define and use macros. Macros are usually referred to as variables when they hold simple string definitions, like CC = clang . Macros in makefiles may be overridden in

5832-496: The target from the components (i.e. source files). If any prerequisite has a more recent timestamp than the target file or the target does not exist as a file, the recipe is performed. The first command may appear on the same line after the prerequisites, separated by a semicolon, for example, Each command line must begin with a tab character. Even though a space is also whitespace , Make requires tab. Since this often leads to confusion and mistakes, this aspect of makefile syntax

5913-459: The trademark UNIX is The Open Group, an industry standards consortium. Only systems fully compliant with and certified to the Single UNIX Specification qualify as "UNIX" (others are called " Unix-like "). By decree of The Open Group, the term "UNIX" refers more to a class of operating systems than to a specific implementation of an operating system; those operating systems which meet The Open Group's Single UNIX Specification should be able to bear

5994-571: The user back to their home directory ). The environment variable PWD (in Unix/Linux shells), or the pseudo-environment variables CD (in Windows COMMAND.COM and cmd.exe , but not in OS/2 and DOS), or _CWD , _CWDS , _CWP and _CWPS (under 4DOS , 4OS2 , 4NT etc.) can be used in scripts, so that one need not start an external program. Microsoft Windows file shortcuts have

6075-454: The very first users: Why the tab in column 1? Yacc was new, Lex was brand new. I hadn't tried either, so I figured this would be a good excuse to learn. After getting myself snarled up with my first stab at Lex, I just did something simple with the pattern newline-tab. It worked, it stayed. And then a few weeks later I had a user population of about a dozen, most of them friends, and I didn't want to screw up my embedded base. The rest, sadly,

6156-531: Was a port of Version 6, made four years later (1977) at the University of Wollongong for the Interdata 7/32 , followed by a Bell Labs port of Version 7 to the Interdata 8/32 during 1977 and 1978. Bell Labs produced several versions of Unix that are collectively referred to as Research Unix . In 1975, the first source license for UNIX was sold to Donald B. Gillies at the University of Illinois Urbana–Champaign (UIUC) Department of Computer Science. During

6237-431: Was commonly used on minicomputers and mainframes from the 1970s onwards. It distinguished itself from its predecessors as the first portable operating system: almost the entire operating system is written in the C programming language , which allows Unix to operate on numerous platforms. Unix systems are characterized by a modular design that is sometimes called the " Unix philosophy ". According to this philosophy,

6318-402: Was one of the key reasons it emerged as an important teaching and learning tool and has had a broad influence. See § Impact , below. The inclusion of these components did not make the system large – the original V7 UNIX distribution, consisting of copies of all of the compiled binaries plus all of the source code and documentation occupied less than 10 MB and arrived on

6399-563: Was released in 1992 and led to the NetBSD and FreeBSD projects. With the 1994 settlement of a lawsuit brought against the University of California and Berkeley Software Design Inc. ( USL v. BSDi ) by Unix System Laboratories , it was clarified that Berkeley had the right to distribute BSD Unix for free if it so desired. Since then, BSD Unix has been developed in several different product branches, including OpenBSD and DragonFly BSD . Because of

6480-516: Was said to "present several interesting capabilities as an ARPANET mini-host". At the time, Unix required a license from Bell Telephone Laboratories that cost US$ 20,000 for non-university institutions, while universities could obtain a license for a nominal fee of $ 150. It was noted that Bell was "open to suggestions" for an ARPANET-wide license. The RFC specifically mentions that Unix "offers powerful local processing facilities in terms of user programs, several compilers , an editor based on QED ,

6561-404: Was subsequently adopted by many commercial Unix vendors. In the 1990s, Unix and Unix-like systems grew in popularity and became the operating system of choice for over 90% of the world's top 500 fastest supercomputers , as BSD and Linux distributions were developed through collaboration by a worldwide network of programmers. In 2000, Apple released Darwin , also a Unix system, which became

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