|
Storage Record
In computer science{{citation needed, date=July 2016, a storage record is: * A group of related data, words, or fields treated as a meaningful unit; for instance, a Name, Address, and Telephone Number can be a "Personal Record". * A self-contained collection of information about a single object; a record is made up of a number of distinct items, called fields. * In IBM mainframes, a ''record'' is a basic unit of device-to-program data transfers. Mainframe files, properly called data sets, are traditionally structured collections of records, as opposed to modern byte stream access files. Records may have a fixed length or variable length. In Unix-like systems, a number of programs (for example, awk, join, and sort) are designed to process data consisting of records (called lines) each separated by newlines, where each record may contain a number of fields separated by spaces, commas, or some other character. See also * Block (data storage) * Object composition * Record (compu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Science
Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to practical disciplines (including the design and implementation of hardware and software). Computer science is generally considered an area of academic research and distinct from computer programming. Algorithms and data structures are central to computer science. The theory of computation concerns abstract models of computation and general classes of problems that can be solved using them. The fields of cryptography and computer security involve studying the means for secure communication and for preventing security vulnerabilities. Computer graphics and computational geometry address the generation of images. Programming language theory considers different ways to describe computational processes, and database theory concerns the management of repositories o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM Mainframes
IBM mainframes are large computer systems produced by IBM since 1952. During the 1960s and 1970s, IBM dominated the large computer market. Current mainframe computers in IBM's line of business computers are developments of the basic design of the IBM System/360. First and second generation From 1952 into the late 1960s, IBM manufactured and marketed several large computer models, known as the IBM 700/7000 series. The first-generation 700s were based on vacuum tubes, while the later, second-generation 7000s used transistors. These machines established IBM's dominance in electronic data processing ("EDP"). IBM had two model categories: one (701, 704, 709, 7030, 7090, 7094, 7040, 7044) for engineering and scientific use, and one (702, 705, 705-II, 705-III, 7080, 7070, 7072, 7074, 7010) for commercial or data processing use. The two categories, scientific and commercial, generally used common peripherals but had completely different instruction sets, and there were incompatibiliti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Set (IBM Mainframe)
In the context of IBM mainframe computers in the S/360 line, a data set (IBM preferred) or dataset is a computer file having a record organization. Use of this term began with, e.g., DOS/360, OS/360, and is still used by their successors, including the current z/OS. Documentation for these systems historically preferred this term rather than '' file''. A data set is typically stored on a direct access storage device (DASD) or magnetic tape, however unit record devices, such as punch card readers, card punches, line printers and page printers can provide input/output (I/O) for a data set (file). Data sets are not unstructured streams of bytes, but rather are organized in various logical record and block structures determined by the DSORG (data set organization), RECFM (record format), and other parameters. These parameters are specified at the time of the data set allocation (creation), for example with Job Control Language DD statements. Within a running program they are store ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Byte Stream
A bitstream (or bit stream), also known as binary sequence, is a sequence of bits. A bytestream is a sequence of bytes. Typically, each byte is an 8-bit quantity, and so the term octet stream is sometimes used interchangeably. An octet may be encoded as a sequence of 8 bits in multiple different ways (see bit numbering) so there is no unique and direct translation between bytestreams and bitstreams. Bitstreams and bytestreams are used extensively in telecommunications and computing. For example, synchronous bitstreams are carried by SONET, and Transmission Control Protocol transports an asynchronous bytestream. Relationship between bitstreams and bytestreams In practice, bitstreams are not used directly to encode bytestreams; a communication channel may use a signalling method that does not directly translate to bits (for instance, by transmitting signals of multiple frequencies) and typically also encodes other information such as framing and error correction together ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix-like
A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-like application is one that behaves like the corresponding Unix command or shell. Although there are general philosophies for Unix design, there is no technical standard defining the term, and opinions can differ about the degree to which a particular operating system or application is Unix-like. Some well-known examples of Unix-like operating systems include Linux and BSD. These systems are often used on servers, as well as on personal computers and other devices. Many popular applications, such as the Apache web server and the Bash shell, are also designed to be used on Unix-like systems. One of the key features of Unix-like systems is their ability to support multiple users and processes simultaneously. This allows users to run multipl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AWK (programming Language)
AWK (''awk'') is a domain-specific language designed for text processing and typically used as a data extraction and reporting tool. Like sed and grep, it is a filter, and is a standard feature of most Unix-like operating systems. The AWK language is a data-driven scripting language consisting of a set of actions to be taken against streams of textual data – either run directly on files or used as part of a pipeline – for purposes of extracting or transforming text, such as producing formatted reports. The language extensively uses the string datatype, associative arrays (that is, arrays indexed by key strings), and regular expressions. While AWK has a limited intended application domain and was especially designed to support one-liner programs, the language is Turing-complete, and even the early Bell Labs users of AWK often wrote well-structured large AWK programs. AWK was created at Bell Labs in the 1970s, and its name is derived from the surnames of its authors: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 a number of 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 printing using redirection. As an example, the two following files list the known fathers and the mothers of some people. Both files have bee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sort (Unix)
In computing, sort is a standard command line program of Unix and Unix-like operating systems, that prints the lines of its input or concatenation of all files listed in its argument list in sorted order. Sorting is done based on one or more sort keys extracted from each line of input. By default, the entire input is taken as sort key. Blank space is the default field separator. The command supports a number of command-line options that can vary by implementation. For instance the "-r" flag will reverse the sort order. History A command that invokes a general sort facility was first implemented within Multics. Later, it appeared in Version 1 Unix. This version was originally written by Ken Thompson at AT&T Bell Laboratories. By Version 4 Thompson had modified it to use pipes, but sort retained an option to name the output file because it was used to sort a file in place. In Version 5, Thompson invented "-" to represent standard input. The version of bundled in GNU coreuti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Line (text File)
{{Unreferenced, date=May 2008 In computing, a line is a unit of organization for text files. A line consists of a sequence of zero or more characters, usually displayed within a single horizontal sequence. Depending on the file system or operating system being used the number of characters on a line may either be predetermined or fixed, or the length may vary from line to line. Fixed-length lines are sometimes called records. With variable-length lines, the end of each line is usually indicated by the presence of one or more special end-of-line characters, such as a line feed or carriage return. A blank line usually refers to a line containing zero characters (not counting any end-of-line characters); though it may also refer to any line that does not contain any visible characters (consisting only of whitespace). Some tools that operate on text files (e.g., editors) provide a mechanism to reference lines by their line number. See also * Newline * Line wrap and word ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Newline
Newline (frequently called line ending, end of line (EOL), next line (NEL) or line break) is a control character or sequence of control characters in character encoding specifications such as ASCII, EBCDIC, Unicode, etc. This character, or a sequence of characters, is used to signify the end of a line of text and the start of a new one. History In the mid-1800s, long before the advent of teleprinters and teletype machines, Morse code operators or telegraphists invented and used Morse code prosigns to encode white space text formatting in formal written text messages. In particular the Morse prosign (mnemonic reak ext) represented by the concatenation of literal textual Morse codes "B" and "T" characters sent without the normal inter-character spacing is used in Morse code to encode and indicate a ''new line'' or ''new section'' in a formal text message. Later, in the age of modern teleprinters, standardized character set control codes were developed to aid in white sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Block (data Storage)
In computing (specifically data transmission and data storage), a block, sometimes called a physical record, is a sequence of bytes or bits, usually containing some whole number of records, having a maximum length; a ''block size''. Data thus structured are said to be ''blocked''. The process of putting data into blocks is called ''blocking'', while ''deblocking'' is the process of extracting data from blocks. Blocked data is normally stored in a data buffer, and read or written a whole block at a time. Blocking reduces the overhead and speeds up the handling of the data stream. For some devices, such as magnetic tape and CKD disk devices, blocking reduces the amount of external storage required for the data. Blocking is almost universally employed when storing data to 9-track magnetic tape, NAND flash memory, and rotating media such as floppy disks, hard disks, and optical discs. Most file systems are based on a block device, which is a level of abstraction for the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object Composition
In computer science, object composition and object aggregation are closely related ways to combine objects or data types into more complex ones. In conversation the distinction between composition and aggregation is often ignored. Common kinds of compositions are objects used in object-oriented programming, tagged unions, sets, sequences, and various graph structures. Object compositions relate to, but are not the same as, data structures. Object composition refers to the logical or conceptual structure of the information, not the implementation or physical data structure used to represent it. For example, a sequence differs from a set because (among other things) the order of the composed items matters for the former but not the latter. Data structures such as arrays, linked lists, hash tables, and many others can be used to implement either of them. Perhaps confusingly, some of the same terms are used for both data structures and composites. For example, "binary tree ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
