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Join (Unix)
join is a command in Unix and Unix-like operating systems that merges the lines of two sorted text files based on the presence of a common field. It is similar to the join operator used in relational databases but operating on text files. Overview The join command takes as input two text files and several options. If no command-line argument is given, this command looks for a pair of lines from the two files having the same first field (a sequence of characters that are different from space), and outputs a line composed of the first field followed by the rest of the two lines. The program arguments specify which character to be used in place of space to separate the fields of the line, which field to use when looking for matching lines, and whether to output lines that do not match. The output can be stored to another file rather than printed using redirection. As an example, the two following files list the known fathers and the mothers of some people. Both files have been ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Douglas McIlroy
Malcolm Douglas McIlroy (born 1932) is an American mathematician, engineer, and programmer. As of 2019 he is an Adjunct Professor of Computer Science at Dartmouth College. McIlroy is best known for having originally proposed Unix pipelines and developed several Unix tools, such as echo, spell, diff, sort, join, graph, speak, and tr. He was also one of the pioneering researchers of macro processors and programming language extensibility. He participated in the design of multiple influential programming languages, particularly PL/I, SNOBOL, ALTRAN, TMG and C++. His seminal work on software componentization and code reuse makes him a pioneer of component-based software engineering and software product line engineering. Biography McIlroy earned his bachelor's degree in engineering physics from Cornell University, and a Ph.D. in applied mathematics from MIT in 1959 for his thesis ''On the Solution of the Differential Equations of Conical Shells'' (advisor Eric Reissner). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Character (computing)
In computing and telecommunications, a character is the internal representation of a character (symbol) used within a computer or system. Examples of characters include letters, numerical digits, punctuation marks (such as "." or "-"), and whitespace. The concept also includes control characters, which do not correspond to visible symbols but rather to instructions to format or process the text. Examples of control characters include carriage return and tab as well as other instructions to printers or other devices that display or otherwise process text. Characters are typically combined into '' strings''. Historically, the term ''character'' was used to denote a specific number of contiguous bits. While a character is most commonly assumed to refer to 8 bits (one byte) today, other options like the 6-bit character code were once popular, and the 5-bit Baudot code has been used in the past as well. The term has even been applied to 4 bits with only 16 possible valu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix Text Processing Utilities
Unix (, ; 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 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). The early versions of Unix—which are retrospectively referred to as " Research Unix"—ran on computers such as the PDP-11 and VAX; Unix 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 (in 1973), which allow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Unix Commands
This is a list of the shell commands of the most recent version of the Portable Operating System Interface (POSIX) IEEE Std 1003.1-2024 which is part of the Single UNIX Specification (SUS). These commands are implemented in many shells on modern Unix, Unix-like and other operating systems. This list does not cover commands for all versions of Unix and Unix-like shells nor other versions of POSIX. See also * GNOME Core Applications * GNU Core Utilities * List of GNU packages * List of KDE applications * List of Unix daemons * Unix philosophy The Unix philosophy, originated by Ken Thompson, is a set of cultural norms and philosophical approaches to Minimalism (computing), minimalist, Modularity (programming), modular software development. It is based on the experience of leading devel ... * References External links IEEE Std 1003.1,2004 specificationsIEEE Std 1003.1,2008 specificationsIEEE Std 1003.1,2024 specifications– configurable list of equivalent pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relational Algebra
In database theory, relational algebra is a theory that uses algebraic structures for modeling data and defining queries on it with well founded semantics (computer science), semantics. The theory was introduced by Edgar F. Codd. The main application of relational algebra is to provide a theoretical foundation for relational databases, particularly query languages for such databases, chief among which is SQL. Relational databases store tabular data represented as relation (database), relations. Queries over relational databases often likewise return tabular data represented as relations. The main purpose of relational algebra is to define Operator (mathematics), operators that transform one or more input relations to an output relation. Given that these operators accept relations as input and produce relations as output, they can be combined and used to express complex queries that transform multiple input relations (whose data are stored in the database) into a single output rela ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Join (SQL)
A join clause in the Structured Query Language (SQL) combines column (database), columns from one or more table (database), tables into a new table. The operation corresponds to a Join (relational algebra), join operation in relational algebra. Informally, a join stitches two tables and puts on the same row records with matching fields : INNER, LEFT OUTER, RIGHT OUTER, FULL OUTER and CROSS. Example tables To explain join types, the rest of this article uses the following tables: Department.DepartmentID is the primary key of the Department table, whereas Employee.DepartmentID is a foreign key. Note that in Employee, "Williams" has not yet been assigned to a department. Also, no employees have been assigned to the "Marketing" department. These are the SQL statements to create the above tables: CREATE TABLE department( DepartmentID INT PRIMARY KEY NOT NULL, DepartmentName VARCHAR(20) ); CREATE TABLE employee ( LastName VARCHAR(20), DepartmentID INT REFERENCE ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Textutils
The GNU Core Utilities or coreutils is a collection of GNU software that implements many standard, Unix-based shell commands. The utilities generally provide POSIX compliant interface when the environment variable is set, but otherwise offers a superset to the standard interface. For example, the utilities support long options and options after parameters. This environment variable enables a different functionality in BSD. Similar collections are available in the FOSS ecosystem, with a slightly different scope and focus (less functionality), or license. For example, BusyBox which is licensed under GPL-2.0-only, and Toybox which is licensed under 0BSD. Commands The commands implemented by coreutils are listed below. Throughout this article and customary for Unix-based systems, the term ''file'' refers to all file system items including regular files and special files such as directories. File utilities * chcon Changes file security context ( SELinux) * chgrp Changes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porting
In software engineering, porting is the process of adapting software for the purpose of achieving some form of execution in a computing environment that is different from the one that a given program (meant for such execution) was originally designed for (e.g., different CPU, operating system, or third party library). The term is also used when software/hardware is changed to make them usable in different environments. Software is ''portable'' when the cost of porting it to a new platform is significantly less than the cost of writing it from scratch. The lower the cost of porting software relative to its implementation cost, the more portable it is said to be. This is distinct from cross-platform software, which is designed from the ground up without any single " native" platform. Etymology The term "port" is derived from the Latin '' portāre'', meaning "to carry". When code is not compatible with a particular operating system or architecture, the code must be "carried" to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Windows API
The Windows API, informally WinAPI, is the foundational application programming interface (API) that allows a computer program to access the features of the Microsoft Windows operating system in which the program is running. Programs can access API functionality via shared-library technologies or via system-file access. Each major version of the Windows API has a distinct name that identifies a compatibility aspect of that version. For example, Win32 is the major version of Windows API that runs on 32-bit systems. The name, Windows API, collectively refers to all versions of this capability of Windows. Microsoft provides developer support via a software development kit, Microsoft Windows SDK, which includes documentation and tools for building software based on the Windows API. Services This section lists notable services provided by the Windows API. Base Services Base services include features such as the file system, devices, processes, threads, and error handl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Native (computing)
Native describes a computing system as operating directly with an underlying technology; with no intervening communication or translation layers. Native software Native software is built to be executed directly by processors that implement a compatible instruction set. A program that runs natively on one platform is runnable on another platform via an emulator if an emulator is available and, generally, with significant runtime speed degradation. For example, games for a Game Boy (typically distributed as a cartridge), generally run natively on a Game Boy which is relatively incompatible with other computer platforms. To run such a game on another processor, software that emulates the Game Boy hardware is required. Cross-platform software can run on multiple processors although possibly requiring it to be re-built for different target systems. Native API A native application programming interface (API) provides direct access to an underlying technology. For example, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UnxUtils
UnxUtils is a collection of utility programs that provide popular Unix-based shell commands ported from GNU implementations as native Windows programs that depend only on Win32 and the Microsoft C- runtime ( msvcrt.dll). The collection was last updated externally on April 15, 2003, by Karl M. Syring. , the most recent release was an open-source project at SourceForge, with the latest binary release in March, 2007 (though the files are dated 2000). The independent distribution included a main zip archive (UnxUtils.zip, 3,365,638 bytes) complemented by more recent updates (UnxUpdates.zip, 878,847 bytes, brought some binaries up to year 2003), but the SourceForge project has no UnxUpdates.zip package. An alternative collection of Unix-based utilities for Windows is GnuWin32. It has later versions of many programs, but requires supporting files (e.g. DLLs). Supported commands include: * agrep *ansi2knr * basename * bc *bison *bunzip2 *bzip2 *bzip2recover * cat *chgrp *chm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microsoft Windows
Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sectors of the computing industry – Windows (unqualified) for a consumer or corporate workstation, Windows Server for a Server (computing), server and Windows IoT for an embedded system. Windows is sold as either a consumer retail product or licensed to Original equipment manufacturer, third-party hardware manufacturers who sell products Software bundles, bundled with Windows. The first version of Windows, Windows 1.0, was released on November 20, 1985, as a graphical operating system shell for MS-DOS in response to the growing interest in graphical user interfaces (GUIs). The name "Windows" is a reference to the windowing system in GUIs. The 1990 release of Windows 3.0 catapulted its market success and led to various other product families ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
