Misplaced Pages

#605394

98-405: ITS, and the software developed on it, were technically and culturally influential far beyond their core user community. Remote "guest" or "tourist" access was easily available via the early ARPANET , allowing many interested parties to informally try out features of the operating system and application programs. The wide-open ITS philosophy and collaborative online community were a major influence on

196-543: A Request for Quotation (RFQ) was issued for 140 potential bidders. Most computer science companies regarded the ARPA proposal as outlandish, and only twelve submitted bids to build a network; of the twelve, ARPA regarded only four as top-rank contractors. At year's end, ARPA considered only two contractors and awarded the contract to build the network to BBN in January 1969. The initial, seven-person BBN team were much aided by

294-519: A flag or switch ) modifies the operation of a command; the effect is determined by the command's program. Options follow the command name on the command line, separated by spaces. A space before the first option is not always required, such as Dir/? and DIR /? in DOS, which have the same effect of listing the DIR command's available options, whereas dir --help (in many versions of Unix) does require

392-507: A help option provides a concise review of the options of a command. The command-line environment may not provide graphical enhancements such as different fonts or extended edit windows found in a GUI. It may be difficult for a new user to become familiar with all the commands and options available, compared with the icons and drop-down menus of a graphical user interface, without reference to manuals. Operating system (OS) command-line interfaces are usually distinct programs supplied with

490-478: A pipeline where the output of one command becomes the input to the next command. One can modify the set of available commands by modifying which paths appear in the PATH environment variable. Under Unix, commands also need be marked as executable files. The directories in the path variable are searched in the order they are given. By re-ordering the path, one can run e.g. \OS2\MDOS\E.EXE instead of \OS2\E.EXE, when

588-438: A CLI, presenting their own prompt to the user and accepting command lines. Other programs support both a CLI and a GUI. In some cases, a GUI is simply a wrapper around a separate CLI executable file . In other cases, a program may provide a CLI as an optional alternative to its GUI. CLIs and GUIs often support different functionality. For example, all features of MATLAB , a numerical analysis computer program, are available via

686-458: A Unix-like CLI. Microsoft provides MKS Inc. 's ksh implementation MKS Korn shell for Windows through their Services for UNIX add-on. Since 2001, the Macintosh operating system macOS has been based on a Unix-like operating system called Darwin . On these computers, users can access a Unix-like command-line interface by running the terminal emulator program called Terminal , which

784-623: A combined effort between people on the ITS machines at MIT and at Stanford University SAIL . The document described much of the terminology, puns, and culture of the two AI Labs and related research groups, and is the direct predecessor of the Hacker's Dictionary (1983), the first compendium of hacker jargon to be issued by a major publisher ( MIT Press ). Different implementations of ITS supported an odd array of peripherals, including an automatic wire stripper devised by hacker Richard Greenblatt, who needed

882-504: A command procedure or script which itself can be treated as a command. These advantages mean that a user must figure out a complex command or series of commands only once, because they can be saved, to be used again. The commands given to a CLI shell are often in one of the following forms: where doSomething is, in effect, a verb , how an adverb (for example, should the command be executed verbosely or quietly ) and toFiles an object or objects (typically one or more files) on which

980-624: A network project. Herzfeld redirected funds in the amount of one million dollars from a ballistic missile defense program to Taylor's budget. Taylor hired Larry Roberts as a program manager in the ARPA Information Processing Techniques Office in January 1967 to work on the ARPANET. Roberts met Paul Baran in February 1967, but did not discuss networks. Roberts asked Frank Westervelt to explore

1078-588: A pure GUI. This is typically the case with operating system command shells . CLIs are also used by systems with insufficient resources to support a graphical user interface. Some computer language systems (such as Python , Forth , LISP , Rexx , and many dialects of BASIC ) provide an interactive command-line mode to allow for rapid evaluation of code. CLIs are often used by programmers and system administrators, in engineering and scientific environments, and by technically advanced personal computer users. CLIs are also popular among people with visual disabilities since

SECTION 10

#1732776754606

1176-424: A supply of pre-stripped jumper wires of various lengths for wire-wrapping computer hardware he and others were prototyping. The device used a stepper motor and a formerly hand-held wire stripper tool and cutter, operated by solenoid , all under computer control from ITS software. The device was accessible by any ITS user, but was disappointingly unreliable in actual use. The Xerox Graphics Printer (XGP), one of

1274-485: A testbed for developing and debugging the 1822 protocol , which was a major undertaking. While they were connected electronically in 1969, network applications were not possible until the Network Control Protocol was implemented in 1970 enabling the first two host-host protocols, remote login ( Telnet ) and file transfer ( FTP ) which were specified and implemented between 1969 and 1973. The network

1372-622: A transatlantic satellite link connected ARPANET to the Norwegian Seismic Array (NORSAR), via the Tanum Earth Station in Sweden, and onward via a terrestrial circuit to a TIP at UCL. UCL provided a gateway for interconnection of the ARPANET with British academic networks, the first international resource sharing network, and carried out some of the earliest experimental research work on internetworking. 1971 saw

1470-513: Is active a program is typically invoked by typing its name followed by command-line arguments (if any). For example, in Unix and Unix-like environments, an example of a command-line argument is: file.s is a command-line argument which tells the program rm to remove the file named file.s . Some programming languages, such as C , C++ and Java , allow a program to interpret the command-line arguments by handling them as string parameters in

1568-591: Is allocated a dedicated end-to-end electronic connection between the two communicating stations. The connection is established by switching systems that connected multiple intermediate call legs between these systems for the duration of the call. The traditional model of the circuit-switched telecommunication network was challenged in the early 1960s by Paul Baran at the RAND Corporation , who had been researching systems that could sustain operation during partial destruction, such as by nuclear war. He developed

1666-600: Is found in the Utilities sub-folder of the Applications folder, or by remotely logging into the machine using ssh . Z shell is the default shell for macOS; Bash, tcsh , and the KornShell are also provided. Before macOS Catalina , Bash was the default. A CLI is used whenever a large vocabulary of commands or queries, coupled with a wide (or arbitrary) range of options, can be entered more rapidly as text than with

1764-556: Is somewhat fitting to end on the note that the ARPANET program has had a strong and direct feedback into the support and strength of computer science, from which the network, itself, sprang. Access to the ARPANET was expanded in 1981 when the National Science Foundation (NSF) funded the Computer Science Network (CSNET). The transatlantic connectivity with NORSAR and UCL later evolved into

1862-516: Is the grammar that all commands must follow. In the case of operating systems , DOS and Unix each define their own set of rules that all commands must follow. In the case of embedded systems , each vendor, such as Nortel , Juniper Networks or Cisco Systems , defines their own proprietary set of rules. These rules also dictate how a user navigates through the system of commands. The semantics define what sort of operations are possible, on what sort of data these operations can be performed, and how

1960-676: The Defense Communications Agency in 1975. Bob Kahn moved to DARPA and, together with Vint Cerf at Stanford University , formulated the Transmission Control Program for internetworking . As this work progressed, a protocol was developed by which multiple separate networks could be joined into a network of networks; this incorporated concepts pioneered in the French CYCLADES project directed by Louis Pouzin . Version 4 of TCP/IP

2058-663: The Digital Equipment Corporation PDP-6 computer, but the majority of ITS development and use was on the later, largely compatible, PDP-10 . Although not used as intensively after about 1986, ITS continued to operate on original hardware at MIT until 1990, and then until 1995 at Stacken Computer Club in Sweden. Today, some ITS implementations continue to be remotely accessible, via emulation of PDP-10 hardware running on modern, low-cost computers supported by interested hackers. ITS introduced many then-new features: The environment seen by ITS users

SECTION 20

#1732776754606

2156-928: The Honeywell DDP-516 computer, configured with 24 KB of expandable magnetic-core memory , and a 16-channel Direct Multiplex Control (DMC) direct memory access unit. The DMC established custom interfaces with each of the host computers and modems. In addition to the front-panel lamps, the DDP-516 computer also features a special set of 24 indicator lamps showing the status of the IMP communication channels. Each IMP could support up to four local hosts and could communicate with up to six remote IMPs via early Digital Signal 0 leased telephone lines. The network connected one computer in Utah with three in California. Later,

2254-546: The NSFNET project in 1986. The ARPANET was formally decommissioned in 1990, after partnerships with the telecommunication and computer industry had assured private sector expansion and commercialization of an expanded worldwide network, known as the Internet. Historically, voice and data communications were based on methods of circuit switching , as exemplified in the traditional telephone network, wherein each telephone call

2352-506: The SATNET . The ARPANET, SATNET and PRNET were interconnected in 1977. The DoD made TCP/IP the standard communication protocol for all military computer networking in 1980. NORSAR and University College London left the ARPANET and began using TCP/IP over SATNET in 1982. On January 1, 1983, known as flag day , TCP/IP protocols became the standard for the ARPANET, replacing the earlier Network Control Protocol. In September 1984 work

2450-552: The University of California, Berkeley , and another for Multics at the Massachusetts Institute of Technology . Taylor recalls the circumstance: "For each of these three terminals, I had three different sets of user commands. So, if I was talking online with someone at S.D.C., and I wanted to talk to someone I knew at Berkeley, or M.I.T., about this, I had to get up from the S.D.C. terminal, go over and log into

2548-551: The hacker culture , as described in Steven Levy's book Hackers , and were the direct forerunners of the free and open-source software , open-design , and Wiki movements. ITS development was initiated in the late 1960s by those (the majority of the MIT AI Lab staff at that time) who disagreed with the direction taken by Project MAC's Multics project (which had started in the mid-1960s), particularly such decisions as

2646-476: The main function . Other languages, such as Python , expose operating system specific API (functionality) through sys module , and in particular sys.argv for command-line arguments . In Unix-like operating systems , a single hyphen used in place of a file name is a special value specifying that a program should handle data coming from the standard input or send data to the standard output . A command-line option or simply option (also known as

2744-584: The request for proposal to build the network. He incorporated Donald Davies ' concepts and designs for packet switching, and sought input from Paul Baran on dynamic routing. In 1969, ARPA awarded the contract to build the Interface Message Processors (IMPs) for the network to Bolt Beranek & Newman (BBN). The design was led by Bob Kahn who developed the first protocol for the network. Roberts engaged Leonard Kleinrock at UCLA to develop mathematical methods for analyzing

2842-451: The 1970s, ARPA did emphasize the goal of "command and control". According to Stephen J. Lukasik , who was deputy director (1967–1970) and Director of DARPA (1970–1975): The goal was to exploit new computer technologies to meet the needs of military command and control against nuclear threats, achieve survivable control of US nuclear forces, and improve military tactical and management decision making. The first four nodes were designated as

2940-430: The ARPANET came out of our frustration that there were only a limited number of large, powerful research computers in the country, and that many research investigators, who should have access to them, were geographically separated from them. The ARPANET used distributed computation and incorporated frequent re-computation of routing tables (automatic routing was technically challenging at the time). These features increased

3038-600: The ARPANET did not exactly share Baran's project's goal, he said his work did contribute to the development of the ARPANET. Minutes taken by Elmer Shapiro of Stanford Research Institute at the ARPANET design meeting of 9–10 October 1967 indicate that a version of Baran's routing method ("hot potato") may be used, consistent with the NPL team's proposal at the Symposium on Operating System Principles in Gatlinburg. Later, in

Incompatible Timesharing System - Misplaced Pages Continue

3136-552: The ARPANET was made between Stanford Research Institute (SRI) and UCLA, by SRI programmer Bill Duvall and UCLA student programmer Charley Kline, at 10:30 pm PST on 29 October 1969 (6:30 UTC on 30 October 1969). Kline connected from UCLA's SDS Sigma 7 Host computer (in Boelter Hall room 3420) to the Stanford Research Institute's SDS 940 Host computer. Kline typed the command "login," but initially

3234-533: The CLI, whereas the MATLAB GUI exposes only a subset of features. In Colossal Cave Adventure from 1975, the user uses a CLI to enter one or two words to explore a cave system. The command-line interface evolved from a form of communication conducted by people over teleprinter (TTY) machines. Sometimes these involved sending an order or a confirmation using telex . Early computer systems often used teleprinter as

3332-532: The Department of Defense allowed the universities to join the network for sharing hardware and software resources. According to Charles Herzfeld, ARPA Director (1965–1967): The ARPANET was not started to create a Command and Control System that would survive a nuclear attack, as many now claim. To build such a system was, clearly, a major military need, but it was not ARPA's mission to do this; in fact, we would have been severely criticized had we tried. Rather,

3430-556: The IMPs (similar to the later concept of routers ), that functioned as gateways interconnecting local resources. Routing, flow control, software design and network control were developed by the BBN team. At each site, the IMPs performed store-and-forward packet switching functions and were interconnected with leased lines via telecommunication data sets ( modems ), with initial data rates of 50 kbit /s . The host computers were connected to

3528-399: The IMPs via custom serial communication interfaces. The system, including the hardware and the packet switching software, was designed and installed in nine months. The BBN team continued to interact with the NPL team with meetings between them taking place in the U.S. and the U.K. As with the NPL network, the first-generation IMPs were built by BBN using a rugged computer version of

3626-553: The Internet backbone for government agencies and universities. The ARPANET project was formally decommissioned in 1990. The original IMPs and TIPs were phased out as the ARPANET was shut down after the introduction of the NSFNet, but some IMPs remained in service as late as July 1990. Command line interface A command-line interface ( CLI ) is a means of interacting with a computer program by inputting lines of text called command-lines . Command-line interfaces emerged in

3724-545: The MIT lab, to control usage of printer supplies which had to be specially ordered. CTSS and ITS file systems have a number of design elements in common. Both have an M.F.D. (master file directory) and one or more U.F.D. (user file directories). Neither of them have nested directories (sub-directories) Both have file names consisting of two names which are a maximum of six-characters long. Both support linked files. ARPANET Early research and development: Merging

3822-524: The PC's serial ports . These were typically used to interface an organization's new PC's with their existing mini- or mainframe computers, or to connect PC to PC. Some of these PCs were running Bulletin Board System software. Early operating system CLIs were implemented as part of resident monitor programs, and could not easily be replaced. The first implementation of the shell as a replaceable component

3920-465: The SDS 940 crashed after he typed two characters. About an hour later, after Duvall adjusted parameters on the machine, Kline tried again and successfully logged in. Hence, the first two characters successfully transmitted over the ARPANET were "lo". The first permanent ARPANET link was established on 21 November 1969, between the IMP at UCLA and the IMP at the Stanford Research Institute. By 5 December 1969,

4018-498: The Windows CMD.EXE programs, the latter groups being based heavily on DEC's RSX-11 and RSTS CLIs. Under most operating systems, it is possible to replace the default shell program with alternatives; examples include 4DOS for DOS, 4OS2 for OS/2, and 4NT / Take Command for Windows. Although the term 'shell' is often used to describe a command-line interpreter, strictly speaking, a 'shell' can be any program that constitutes

Incompatible Timesharing System - Misplaced Pages Continue

4116-464: The basis of Infocom 's programming environment), and Scheme . Among other significant and influential software subsystems developed on ITS, the Macsyma symbolic algebra system, started in 1968, was the first widely-known mathematical computing environment. It was a forerunner of Maxima , MATLAB , Wolfram Mathematica , and many other computer algebra systems . Terry Winograd 's SHRDLU program

4214-466: The civil and military networks reduced the 113-node ARPANET by 68 nodes. After MILNET was split away, the ARPANET would continue to be used as an Internet backbone for researchers, but be slowly phased out. In 1985, the NSF funded the establishment of national supercomputing centers at several universities and provided network access and network interconnectivity with the NSFNET project in 1986. NSFNET became

4312-423: The command In zsh the $ RPROMPT variable controls an optional prompt on the right-hand side of the display. It is not a real prompt in that the location of text entry does not change. It is used to display information on the same line as the prompt, but right-justified. In RISC OS the command prompt is a * symbol, and thus (OS) CLI commands are often referred to as star commands . One can also access

4410-670: The command line interface as the primary user interface replaced by the Graphical User Interface . The command line remained available as an alternative user interface, often used by system administrators and other advanced users for system administration, computer programming and batch processing . In November 2006, Microsoft released version 1.0 of Windows PowerShell (formerly codenamed Monad ), which combined features of traditional Unix shells with their proprietary object-oriented .NET Framework . MinGW and Cygwin are open-source packages for Windows that offer

4508-399: The command should act. The > in the third example is a redirection operator , telling the command-line interpreter to send the output of the command not to its own standard output (the screen) but to the named file. This will overwrite the file. Using >> will redirect the output and append it to the file. Another redirection operator is the vertical bar ( | ), which creates

4606-431: The commands and responses can be displayed using refreshable Braille displays . The general pattern of a command line interface is: In this format, the delimiters between command-line elements are whitespace characters and the end-of-line delimiter is the newline delimiter. This is a widely used (but not universal) convention. A CLI can generally be considered as consisting of syntax and semantics . The syntax

4704-466: The commands. Alternatives to CLIs include GUIs (most notably desktop metaphors with a mouse pointer , such as Microsoft Windows ), text-based user interface menus (such as DOS Shell and IBM AIX SMIT ), and keyboard shortcuts . Compared with a graphical user interface, a command-line interface requires fewer system resources to implement. Since options to commands are given in a few characters in each command line, an experienced user often finds

4802-708: The concept of the " Intergalactic Computer Network ". Those ideas encompassed many of the features of the contemporary Internet. In October 1963, Licklider was appointed head of the Behavioral Sciences and Command and Control programs at the Defense Department's Advanced Research Projects Agency (ARPA). He convinced Ivan Sutherland and Bob Taylor that this network concept was very important and merited development, although Licklider left ARPA before any contracts were assigned for development. Sutherland and Taylor continued their interest in creating

4900-407: The current time, user, shell number or working directory) in order, for instance, to make the prompt more informative or visually pleasing, to distinguish sessions on various machines, or to indicate the current level of nesting of commands. On some systems, special tokens in the definition of the prompt can be used to cause external programs to be called by the command-line interpreter while displaying

4998-422: The default is the opposite. Renaming of the executables also works: people often rename their favourite editor to EDIT, for example. The command line allows one to restrict available commands, such as access to advanced internal commands. The Windows CMD.EXE does this. Often, shareware programs will limit the range of commands, including printing a command 'your administrator has disabled running batch files' from

SECTION 50

#1732776754606

5096-501: The features that are commonly considered to produce structured programs. The Bourne shell led to the development of the KornShell (ksh), Almquist shell (ash), and the popular Bourne-again shell (or Bash). Early microcomputers themselves were based on a command-line interface such as CP/M , DOS or AppleSoft BASIC . During the 1980s and 1990s, the introduction of the Apple Macintosh and of Microsoft Windows on PCs saw

5194-506: The first Multics shell was developed by Glenda Schroeder . The first Unix shell , the V6 shell , was developed by Ken Thompson in 1971 at Bell Labs and was modeled after Schroeder's Multics shell. The Bourne shell was introduced in 1977 as a replacement for the V6 shell. Although it is used as an interactive command interpreter, it was also intended as a scripting language and contains most of

5292-473: The first laser printers in the world, was supported by ITS by 1974. The MIT AI Lab had one of these prototype continuous roll-fed printers for experimentation and use by its staff. By 1982, the XGP was supplemented by a Xerox Dover printer, an early sheet-fed laser printer. Although any ITS user could access the laser printers, physical access to pick up printouts was limited to staff and others who obtained access to

5390-412: The grammar represents these operations and data—the symbolic meaning in the syntax. Two different CLIs may agree on either syntax or semantics, but it is only when they agree on both that they can be considered sufficiently similar to allow users to use both CLIs without needing to learn anything, as well as to enable re-use of scripts. A simple CLI will display a prompt, accept a command line typed by

5488-503: The inclusion of powerful system security . The name was chosen by Tom Knight as a joke on the name of the earliest MIT time-sharing operating system, the Compatible Time-Sharing System , which dated from the early 1960s. By simplifying their system compared to Multics, ITS's authors were able to quickly produce a functional operating system for their lab. ITS was written in assembly language , originally for

5586-542: The initial four-node network was established. Elizabeth Feinler created the first Resource Handbook for ARPANET in 1969 which led to the development of the ARPANET directory. The directory, built by Feinler and a team made it possible to navigate the ARPANET. In 1968, Roberts contracted with Kleinrock to measure the performance of the network and find areas for improvement. Building on his earlier work on queueing theory and optimization of packet delay in communication networks, Kleinrock specified mathematical models of

5684-501: The interface mode. At this point, commands from the system mode may not be accessible until the user exits the interface mode and enters the system mode. A command prompt (or just prompt ) is a sequence of (one or more) characters used in a command-line interface to indicate readiness to accept commands. It literally prompts the user to take action. A prompt usually ends with one of the characters $ , % , # , : , > or - and often includes other information, such as

5782-598: The means of interaction with an operator. The mechanical teleprinter was replaced by a "glass tty" , a keyboard and screen emulating the teleprinter. "Smart" terminals permitted additional functions, such as cursor movement over the entire screen, or local editing of data on the terminal for transmission to the computer. As the microcomputer revolution replaced the traditional – minicomputer + terminals – time sharing architecture, hardware terminals were replaced by terminal emulators  — PC software that interpreted terminal signals sent through

5880-706: The mid-1960s, on computer terminals , as an interactive and more user-friendly alternative to the non-interactive interface available with punched cards . Today, most computer users rely on graphical user interfaces ("GUIs") instead of CLIs. However, many programs and operating system utilities lack GUIs, and are intended to be used through CLIs. Knowledge of CLIs is also useful for writing scripts . Programs that have CLIs are generally easy to automate via scripting, since command-lines, being mere lines of text, are easy to specify in code. CLIs are made possible by command-line interpreters or command-line processors , which are programs that read command-lines and carry out

5978-587: The network, in part, to allow ARPA-sponsored researchers at various corporate and academic locales to utilize computers provided by ARPA, and, in part, to quickly distribute new software and other computer science results. Taylor had three computer terminals in his office, each connected to separate computers, which ARPA was funding: one for the System Development Corporation (SDC) Q-32 in Santa Monica , one for Project Genie at

SECTION 60

#1732776754606

6076-539: The networks and creating the Internet: Commercialization, privatization, broader access leads to the modern Internet: Examples of Internet services: The Advanced Research Projects Agency Network ( ARPANET ) was the first wide-area packet-switched network with distributed control and one of the first computer networks to implement the TCP/IP protocol suite. Both technologies became

6174-461: The newer C:\> style, unless used on floppy drives A: or B:; on those systems PROMPT $ N$ G can be used to override the automatic default and explicitly switch to the older style. Many Unix systems feature the $ PS1 variable (Prompt String 1), although other variables also may affect the prompt (depending on the shell used). In the Bash shell, a prompt of the form: could be set by issuing

6272-515: The operating system. A program that implements such a text interface is often called a command-line interpreter, command processor or shell . Examples of command-line interpreters include Nushell , DEC's DIGITAL Command Language (DCL) in OpenVMS and RSX-11 , the various Unix shells ( sh , ksh , csh , tcsh , zsh , Bash , etc.), CP/M 's CCP , DOS ' COMMAND.COM , as well as the OS/2 and

6370-422: The options easier to access. Automation of repetitive tasks is simplified by line editing and history mechanisms for storing frequently used sequences; this may extend to a scripting language that can take parameters and variable options. A command-line history can be kept, allowing review or repetition of commands. A command-line system may require paper or online manuals for the user's reference, although often

6468-457: The other terminal and get in touch with them. I said, 'Oh Man!', it's obvious what to do: If you have these three terminals, there ought to be one terminal that goes anywhere you want to go. That idea is the ARPANET". Donald Davies' work caught the attention of ARPANET developers at Symposium on Operating Systems Principles in October 1967. He gave the first public presentation, having coined

6566-494: The packet network technology. The first computers were connected in 1969 and the Network Control Protocol was implemented in 1970, development of which was led by Steve Crocker at UCLA and other graduate students, including Jon Postel and others. The network was declared operational in 1971. Further software development enabled remote login and file transfer , which was used to provide an early form of email . The network expanded rapidly and operational control passed to

6664-468: The path of the current working directory and the hostname . On many Unix and derivative systems , the prompt commonly ends in $ or % if the user is a normal user, but in # if the user is a superuser ("root" in Unix terminology). End-users can often modify prompts. Depending on the environment, they may include colors, special characters, and other elements (like variables and functions for

6762-615: The performance of packet-switched networks, which underpinned the development of the ARPANET as it expanded rapidly in the early 1970s. Roberts engaged Howard Frank to consult on the topological design of the network. Frank made recommendations to increase throughput and reduce costs in a scaled-up network. By March 1970, the ARPANET reached the East Coast of the United States, when an IMP at BBN in Cambridge, Massachusetts

6860-428: The prompt. Some CLIs, such as those in network routers , have a hierarchy of modes , with a different set of commands supported in each mode. The set of commands are grouped by association with security, system, interface, etc. In these systems the user might traverse through a series of sub-modes. For example, if the CLI had two modes called interface and system , the user might use the command interface to enter

6958-548: The prompt. In DOS' COMMAND.COM and in Windows NT's cmd.exe users can modify the prompt by issuing a PROMPT command or by directly changing the value of the corresponding %PROMPT% environment variable . The default of most modern systems, the C:\>; style is obtained, for instance, with PROMPT $ P$ G . The default of older DOS systems, C> is obtained by just PROMPT , although on some systems this produces

7056-518: The questions of message size and contents for the network, and to write a position paper on the intercomputer communication protocol including “conventions for character and block transmission, error checking and re-transmission, and computer and user identification." In April 1967, ARPA held a design session on technical standards. The initial standards for identification and authentication of users, transmission of characters, and error checking and retransmission procedures were discussed. Roberts' proposal

7154-463: The same commands from other command lines (such as the BBC BASIC command line), by preceding the command with a * . A command-line argument or parameter is an item of information provided to a program when it is started. A program can have many command-line arguments that identify sources or destinations of information, or that alter the operation of the program. When a command processor

7252-442: The start of the use of the non-ruggedized (and therefore significantly lighter) Honeywell 316 as an IMP. It could also be configured as a Terminal Interface Processor (TIP), which provided terminal server support for up to 63 ASCII serial terminals through a multi-line controller in place of one of the hosts. The 316 featured a greater degree of integration than the 516, which made it less expensive and easier to maintain. The 316

7350-555: The survivability of the network in the event of significant interruption. Furthermore, the ARPANET was designed to survive subordinate network losses. However, the Internet Society agrees with Herzfeld in a footnote in their online article, A Brief History of the Internet : It was from the RAND study that the false rumor started, claiming that the ARPANET was somehow related to building a network resistant to nuclear war. This

7448-638: The technical foundation of the Internet . The ARPANET was established by the Advanced Research Projects Agency (now DARPA) of the United States Department of Defense . Building on the ideas of J. C. R. Licklider , Bob Taylor initiated the ARPANET project in 1966 to enable resource sharing between remote computers. Taylor appointed Larry Roberts as program manager. Roberts made the key decisions about

7546-466: The technical specificity of their response to the ARPA RFQ, and thus quickly produced the first working system. The "IMP guys" were led by Frank Heart ; the theoretical design of the network was led by Bob Kahn ; the team included Dave Walden , Severo Ornstein , William Crowther and several others. The BBN-proposed network closely followed Roberts' ARPA plan: a network composed of small computers,

7644-585: The term packet switching , in August 1968 and incorporated it into the NPL network in England. The NPL network and ARPANET were the first two networks in the world to implement packet switching. Roberts said the computer networks built in the 1970s were similar "in nearly all respects" to Davies' original 1965 design. In February 1966, Bob Taylor successfully lobbied ARPA's Director Charles M. Herzfeld to fund

7742-663: The theoretical model of distributed adaptive message block switching . However, the telecommunication establishment rejected the development in favor of existing models. Donald Davies at the United Kingdom's National Physical Laboratory (NPL) independently arrived at a similar concept in 1965. The earliest ideas for a computer network intended to allow general communications among computer users were formulated by computer scientist J. C. R. Licklider of Bolt Beranek and Newman (BBN), in April 1963, in memoranda discussing

7840-455: The user terminated by the Enter key , then execute the specified command and provide textual display of results or error messages. Advanced CLIs will validate, interpret and parameter-expand the command line before executing the specified command, and optionally capture or redirect its output. Unlike a button or menu item in a GUI, a command line is typically self-documenting, stating exactly what

7938-410: The user wants done. In addition, command lines usually include many defaults that can be changed to customize the results. Useful command lines can be saved by assigning a character string or alias to represent the full command, or several commands can be grouped to perform a more complex sequence – for instance, compile the program, install it, and run it — creating a single entity, called

8036-615: The user-interface, including fully graphically oriented ones. For example, the default Windows GUI is a shell program named EXPLORER.EXE , as defined in the SHELL=EXPLORER.EXE line in the WIN.INI configuration file. These programs are shells, but not CLIs. Application programs (as opposed to operating systems) may also have command-line interfaces. An application program may support none, any, or all of these three major types of command-line interface mechanisms: Some applications support

8134-449: Was added in 1970, although considerations of cost and IMP processing power meant this capability was not actively used. Larry Roberts saw the ARPANET and NPL projects as complementary and sought in 1970 to connect them via a satellite link. Peter Kirstein 's research group at University College London (UCL) was subsequently chosen in 1971 in place of NPL for the UK connection. In June 1973,

8232-495: Was called PEEK. The local spelling "TURIST" is an artifact of six-character filename (and other identifier) limitations, which is traceable to six SIXBIT encoded characters fitting into a single 36-bit PDP-10 word. "TURIST" may also have been a pun on Alan Turing , a pioneer of theoretical computer science . The less-complimentary term " LUSER " was also applied to guest users, especially those who repeatedly engaged in clueless or vandalous behavior. The Jargon File started as

8330-473: Was completed on restructuring the ARPANET giving U.S. military sites their own Military Network ( MILNET ) for unclassified defense department communications. Both networks carried unclassified information and were connected at a small number of controlled gateways which would allow total separation in the event of an emergency. MILNET was part of the Defense Data Network (DDN). Separating

8428-606: Was configured with 40 kB of core memory for a TIP. The size of core memory was later increased, to 32 kB for the IMPs, and 56 kB for TIPs, in 1973. The ARPANET was demonstrated at the International Conference on Computer Communications in October 1972. In 1975, BBN introduced IMP software running on the Pluribus multi-processor . These appeared in a few sites. In 1981, BBN introduced IMP software running on its own C/30 processor product. ARPA

8526-549: Was connected to the network. Thereafter, the ARPANET grew: 9 IMPs by June 1970 and 13 IMPs by December 1970, then 18 by September 1971 (when the network included 23 university and government hosts); 29 IMPs by August 1972, and 40 by September 1973. By June 1974, there were 46 IMPs, and in July 1975, the network numbered 57 IMPs. By 1981, the number was 213 host computers, with another host connecting approximately every twenty days. Support for inter-IMP circuits of up to 230.4 kbit/s

8624-606: Was declared operational in 1971. Network traffic began to grow once email was established at the majority of sites by around 1973. The initial ARPANET configuration linked UCLA , ARC , UCSB , and the University of Utah School of Computing . The first node was created at UCLA, where Leonard Kleinrock could evaluate network performance and examine his theories on message delay . The locations were selected not only to reduce leased line costs but also because each had specific expertise beneficial for this initial implementation phase: The first successful host-to-host connection on

8722-666: Was developed in ITS. The computer game Zork was also originally written on ITS. Richard Greenblatt 's Mac Hack VI was the top-rated chess program for years and was the first to display a graphical board representation. The default ITS top-level command interpreter was the PDP-10 machine language debugger ( DDT ). The usual text editor on ITS was TECO and later Emacs , which was written in TECO. Both DDT and TECO were implemented through simple dispatch tables on single-letter commands, and thus had no true syntax . The ITS task manager

8820-464: Was installed in the ARPANET for production use in January 1983 after the Department of Defense made it standard for all military computer networking. Access to the ARPANET was expanded in 1981 when the National Science Foundation (NSF) funded the Computer Science Network (CSNET). In the early 1980s, the NSF funded the establishment of national supercomputing centers at several universities and provided network access and network interconnectivity with

8918-502: Was intended to fund advanced research. The ARPANET was a research project that was communications-oriented, rather than user-oriented in design. Nonetheless, in the summer of 1975, operational control of the ARPANET passed to the Defense Communications Agency . At about this time, the first ARPANET encryption devices were deployed to support classified traffic. The ARPANET Completion Report , written in 1978 and published in 1981 jointly by BBN and DARPA , concludes that:  ... it

9016-423: Was never true of the ARPANET, but was an aspect of the earlier RAND study of secure communication. The later work on internetworking did emphasize robustness and survivability, including the capability to withstand losses of large portions of the underlying networks. Paul Baran , the first to put forward a theoretical model for communication using packet switching, conducted the RAND study referenced above. Though

9114-568: Was part of the Multics time-sharing operating system . In 1964, MIT Computation Center staff member Louis Pouzin developed the RUNCOM tool for executing command scripts while allowing argument substitution. Pouzin coined the term shell to describe the technique of using commands like a programming language, and wrote a paper about how to implement the idea in the Multics operating system. Pouzin returned to his native France in 1965, and

9212-448: Was philosophically significantly different from that provided by most operating systems at the time. The wide-open ITS philosophy and collaborative community were the direct forerunner of the free and open-source software , open-design , and Wiki movements. The EMACS ("Editor MACroS") editor was originally written on ITS. In its ITS instantiation it was a collection of TECO programs (called "macros"). On later operating systems, it

9310-434: Was presented at the inaugural Symposium on Operating Systems Principles in October 1967. Donald Davies' work on packet switching and the NPL network, presented by a colleague ( Roger Scantlebury ), and that of Paul Baran, came to the attention of the ARPA investigators at this conference. Roberts applied Davies' concept of packet switching for the ARPANET, and sought input from Paul Baran on dynamic routing. The NPL network

9408-461: Was that all mainframe computers would connect to one another directly. The other investigators were reluctant to dedicate these computing resources to network administration. After the design session, Wesley Clark proposed minicomputers should be used as an interface to create a message switching network. Roberts modified the ARPANET plan to incorporate Clark's suggestion and named the minicomputers Interface Message Processors (IMPs). The plan

9506-480: Was using line speeds of 768 kbit/s, and the proposed line speed for the ARPANET was upgraded from 2.4 kbit/s to 50 kbit/s. By mid-1968, Roberts and Barry Wessler wrote a final version of the IMP specification based on a Stanford Research Institute (SRI) report that ARPA commissioned to write detailed specifications describing the ARPANET communications network. Roberts gave a report to Taylor on 3 June, who approved it on 21 June. After approval by ARPA,

9604-608: Was written in the common language of those systems – for example, the C language under Unix, and Zetalisp under the Lisp Machine system. GNU ‘s info help system was originally an EMACS subsystem, and then was later written as a complete standalone system for Unix-like machines. Several important programming languages and systems were developed on ITS, including MacLisp (the precursor of Zetalisp and Common Lisp ), Microplanner (implemented in MacLisp), MDL (which became

#605394