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Command (computing)
In computing, a command is an instruction received via an external Interface (computing), interface that directs the behavior of a computer program. Commonly, commands are sent to a program via a command-line interface, a scripting language, script, a network protocol, or as an event triggered in a graphical user interface. Many commands support arguments to specify input and to modify default behavior. Terminology and syntax varies but there are notable common approaches. Typically, an option or a flag is a name (without Whitespace character, whitespace) with a prefix such as dash or Slash (punctuation), slash that modifies default behavior. An option might have a required value that follows it. Typically, flag refers to an option that does not have a following value. A parameter is an argument that specifies input to the command and its meaning is based on its position in the command line relative to other parameters; generally ignoring options. A parameter can specify anything ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, hardware and software. Computing has scientific, engineering, mathematical, technological, and social aspects. Major computing disciplines include computer engineering, computer science, cybersecurity, data science, information systems, information technology, and software engineering. The term ''computing'' is also synonymous with counting and calculation, calculating. In earlier times, it was used in reference to the action performed by Mechanical computer, mechanical computing machines, and before that, to Computer (occupation), human computers. History The history of computing is longer than the history of computing hardware and includes the history of methods intended for pen and paper (or for chalk and slate) with or without the aid of tables. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Printf (Unix)
printf is a shell command that formats and outputs text like the same-named C function. It is available in a variety of Unix and Unix-like systems. Some shells implement the command as builtin and some provide it as a utility program The command has similar syntax and semantics as the library function. The command outputs text to standard output as specified by a format string and a list of values. Characters of the format string are copied to the output verbatim except when a format specifier is found which causes a value to be output per the specifier. The command has some aspects unlike the library function. In addition to the library function format specifiers, %b causes the command to expand backslash escape sequences (for example \n for newline), and %q outputs an item that can be used as shell input. The value used for an unmatched specifier (too few values) is an empty string for or 0 for a numeric specifier. If there are more values than specifiers, then the comma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formal Grammar
A formal grammar is a set of Terminal and nonterminal symbols, symbols and the Production (computer science), production rules for rewriting some of them into every possible string of a formal language over an Alphabet (formal languages), alphabet. A grammar does not describe the semantics, meaning of the strings — only their form. In applied mathematics, formal language theory is the discipline that studies formal grammars and languages. Its applications are found in theoretical computer science, theoretical linguistics, Formal semantics (logic), formal semantics, mathematical logic, and other areas. A formal grammar is a Set_(mathematics), set of rules for rewriting strings, along with a "start symbol" from which rewriting starts. Therefore, a grammar is usually thought of as a language generator. However, it can also sometimes be used as the basis for a "recognizer"—a function in computing that determines whether a given string belongs to the language or is grammatical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dir (command)
dir, short for ''directory'', is a shell (computing), shell command (computing), command for listing file system contents; computer file, files and file directory, directories. Arguably, the command provides the same essential functionality as the ls command, but typically the two commands are described as notably separate concepts, possibly since is implemented from a codebase that shares more history than many implementations. The command is often implemented as internal in the operating system shell (computing), shell instead of as a separate application as many other commands are. Implementations Although syntax, semantics and implementations vary, a command is available in the command-line interface (CLI) of the operating systems Digital Research CP/M, MP/M, Intel ISIS (operating system), ISIS-II, RMX (operating system), iRMX 86, Cromemco Cromemco DOS, CDOS, MetaComCo TRIPOS, DOS, IBM/Toshiba 4690 Operating System, 4690 OS, IBM OS/2, Microsoft Windows, Singularity (op ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TYPE (DOS Command)
In computing, is a command in various command-line interpreters ( shells) such as COMMAND.COM, cmd.exe, 4DOS/ 4NT and Windows PowerShell used to display the contents of specified files on the computer terminal. The analogous Unix command is . Implementations The command is available in the operating systems DEC RT-11, OS/8,"Concise Command Language" (CCL). RSX-11, TOPS-10, TOPS-20, VMS, Digital Research CP/M, MP/M, MetaComCo TRIPOS, Heath Company HDOS, AmigaDOS, DOS, FlexOS, TSL PC-MOS, SpartaDOS X, IBM/Toshiba 4690 OS, IBM OS/2, Microsoft Windows, ReactOS, AROS, and SymbOS. The type command is supported by Tim Paterson's SCP 86-DOS. On MS-DOS, the command is available in versions 1 and later. DR DOS 6.0 also includes an implementation of the command. It is also available in the open source MS-DOS emulator DOSBox and the EFI shell. In Windows PowerShell, ' is a predefined command alias for the Cmdlet which basically serves the same purpose. originated as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OS/2
OS/2 is a Proprietary software, proprietary computer operating system for x86 and PowerPC based personal computers. It was created and initially developed jointly by IBM and Microsoft, under the leadership of IBM software designer Ed Iacobucci, intended as a replacement for DOS. The first version was released in 1987. A feud between the two companies beginning in 1990 led to Microsoft’s leaving development solely to IBM, which continued development on its own. OS/2 Warp 4 in 1996 was the last major upgrade, after which IBM slowly halted the product as it failed to compete against Microsoft's Microsoft Windows, Windows; updated versions of OS/2 were released by IBM until 2001. The name stands for "Operating System/2", because it was introduced as part of the same generation change release as IBM's "IBM Personal System/2, Personal System/2 (PS/2)" line of second-generation PCs. OS/2 was intended as a protected mode, protected-mode successor of IBM PC DOS, PC DOS targeting t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Terminal
A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. Most early computers only had a front panel to input or display bits and had to be connected to a terminal to print or input text through a keyboard. Teleprinters were used as early-day hard-copy terminals and predated the use of a computer screen by decades. The computer would typically transmit a line of data which would be printed on paper, and accept a line of data from a keyboard over a serial or other interface. Starting in the mid-1970s with microcomputers such as the Sphere 1, Sol-20, and Apple I, display circuitry and keyboards began to be integrated into personal and workstation computer systems, with the computer handling character generation and outputting to a CRT display such as a computer monitor or, sometimes, a consumer TV, but most larger computers continued to require terminal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standard Output
Standard may refer to: Symbols * Colours, standards and guidons, kinds of military signs * Standard (emblem), a type of a large symbol or emblem used for identification Norms, conventions or requirements * Standard (metrology), an object that bears a defined relationship to a unit of measure used for calibration of measuring devices * Standard (timber unit), an obsolete measure of timber used in trade * Breed standard (also called bench standard), in animal fancy and animal husbandry * BioCompute Standard, a standard for next generation sequencing * ''De facto'' standard, product or system with market dominance * Gold standard, a monetary system based on gold; also used metaphorically for the best of several options, against which the others are measured * Internet Standard, a specification ratified as an open standard by the Internet Engineering Task Force * Learning standards, standards applied to education content * Standard displacement, a naval term describing th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echo (command)
echo is shell command that writes input text to standard output. It is available in many operating system and shells. It is often used in a shell script to log status, provide feedback to the user and for debugging. For an interactive session, output by default displays on the terminal screen, but output can be re-directed to a file or piped to another process. Many shells implement echo as a builtin command rather than an external application as are many other commands. Multiple, incompatible implementations of echo exist in different shells. Some expand escape sequences by default; some do not; some accept options; some do not. The POSIX specification leaves the behavior unspecified if the first argument is -n or any argument contains backslash characters while the Unix specification (XSI option in POSIX) mandates the expansion of some sequences and does not allow any option processing. In practice, many echo implementations are not compliant in the default environm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cd (command)
is a shell command that changes the working directory. It is available in many shells and other applications that maintain a working directory. In some contexts, the command can perform actions other than change directory. Some environments provide the change directory feature via a different command name such as . Implementations Generally, a computer system that provides access to a hierarchical file system, provides a change directory command to set the working directory. As this applies to most operating system shells, most support a change directory command, including Unix and Unix-like (i.e. Linux) shells, and Microsoft shells including Command Prompt and PowerShell. Other operating systems with shells supporting the command include OS/2, TRIPOS, AmigaOS (where the command is implied for an input path), ReactOS, DOSBox, and UEFI. * On MS-DOS, the command is available in version 2 and later * DR DOS 6.0 includes the command as both and * On HP MPE/iX the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 a process refers to a file using a path that is a relative path, such as a path on a Unix-like system that does not begin with a / (forward slash) or a path on Windows that does not begin with a \ (backward slash), the path is interpreted as relative to the process's working directory. So, for example a process on a Unix-like system with working directory /rabbit-shoes that attempts to create the file foo.txt will end up creating the file /rabbit-shoes/foo.txt. In operating systems In most computer file systems, every directory has an entry (usually named ".") which points to the directory itself. In most DOS and UNIX command shells, as well as in the Microsoft Windows command line interpreters cmd.exe and Wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bash (Unix Shell)
In computing, Bash (short for "''Bourne Again SHell''") is an interactive command interpreter and command programming language developed for UNIX-like operating systems. Created in 1989 by Brian Fox for the GNU Project, it is supported by the Free Software Foundation and designed as a 100% free alternative for the Bourne shell (sh) and other proprietary Unix shells. Since its inception, Bash has gained widespread adoption and is commonly used as the default login shell for numerous Linux distributions. It holds historical significance as one of the earliest programs ported to Linux by Linus Torvalds, alongside the GNU Compiler ( GCC). It is available on nearly all modern operating systems, making it a versatile tool in various computing environments. As a command-line interface (CLI), Bash operates within a terminal emulator, or text window, where users input commands to execute various tasks. It also supports the execution of commands from files, known as shell scripts, f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
