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Filter (Unix)
A filter is a computer program or subroutine to process a stream, producing another stream. While a single filter can be used individually, they are frequently strung together to form a pipeline. Some operating systems such as Unix are rich with filter programs. Windows 7 and later are also rich with filters, as they include Windows PowerShell. In comparison, however, few filters are built into cmd.exe (the original command-line interface of Windows), most of which have significant enhancements relative to the similar filter commands that were available in MS-DOS. OS X includes filters from its underlying Unix base but also has Automator, which allows filters (known as "Actions") to be strung together to form a pipeline. Unix In Unix and Unix-like operating systems, a filter is a program that gets most of its data from its standard input (the main input stream) and writes its main results to its standard output (the main output stream). Auxiliary input may come from command line ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Program
A computer program is a sequence or set of instructions in a programming language for a computer to Execution (computing), execute. It is one component of software, which also includes software documentation, documentation and other intangible components. A ''computer program'' in its human-readable form is called source code. Source code needs another computer program to Execution (computing), execute because computers can only execute their native machine instructions. Therefore, source code may be Translator (computing), translated to machine instructions using a compiler written for the language. (Assembly language programs are translated using an Assembler (computing), assembler.) The resulting file is called an executable. Alternatively, source code may execute within an interpreter (computing), interpreter written for the language. If the executable is requested for execution, then the operating system Loader (computing), loads it into Random-access memory, memory and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ken Thompson
Kenneth Lane Thompson (born February 4, 1943) is an American pioneer of computer science. Thompson worked at Bell Labs for most of his career where he designed and implemented the original Unix operating system. He also invented the B (programming language), B programming language, the direct predecessor to the C (programming language), C language, and was one of the creators and early developers of the Plan 9 from Bell Labs, Plan 9 operating system. Since 2006, Thompson has worked at Google, where he co-developed the Go (programming language), Go language. A recipient of the Turing award, he is considered one of the greatest computer programmers of all time. Other notable contributions included his work on regular expressions and early computer text editors QED (text editor), QED and ed (text editor), ed, the definition of the UTF-8 encoding, and his work on computer chess that included the creation of endgame tablebases and the chess machine Belle (chess machine), Belle. He won ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compress
compress is a Unix shell compression program based on the LZW compression algorithm. Compared to gzip's fastest setting, compress is slightly slower at compression, slightly faster at decompression, and has a significantly lower compression ratio. 1.8 MiB of memory is used to compress the Hutter Prize data, slightly more than gzip's slowest setting. The uncompress utility will restore files to their original state after they have been compressed using the ''compress'' utility. If no files are specified, the standard input will be uncompressed to the standard output. Description Files compressed by ''compress'' are typically given the extension ".Z" (modeled after the earlier pack program which used the extension ".z"). Most ''tar'' programs will pipe their data through ''compress'' when given the command line option "-Z". (The ''tar'' program in its own does not compress; it just stores multiple files within one tape archive.) Files can be returned to their original ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comm
The command in the Unix family of computer operating systems is a utility that is used to compare two files for common and distinct lines. is specified in the POSIX standard. It has been widely available on Unix-like operating systems since the mid to late 1980s. History Written by Lee E. McMahon, first appeared in Version 4 Unix. The version of bundled in GNU coreutils was written by Richard Stallman and David MacKenzie. Usage reads two files as input, regarded as lines of text. outputs one file, which contains three columns. The first two columns contain lines unique to the first and second file, respectively. The last column contains lines common to both. This functionally is similar to . Columns are typically distinguished with the character. If the input files contain lines beginning with the separator character, the output columns can become ambiguous. For efficiency, standard implementations of expect both input files to be sequenced in the same line colla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cat (Unix)
cat is a shell command for writing the content of a file or input stream to standard output. The name is an abbreviation of ''concatenate'' which is from the Latin ''catenare'' meaning "to chain" Originally developed for Unix, it is available on many operating systems and shells today. In addition to combining files, cat is commonly used to copy files and in particular to copy a file to the terminal monitor. Unless re-directed, outputs file content on-screen. History cat was part of the early versions of Unix, e.g., Version 1. It replaced pr, a PDP-7 and Multics command for copying a single file to the screen. It was written by Ken Thompson and Dennis Ritchie. The implementation of cat bundled in GNU coreutils was written by Torbjorn Granlund and Richard Stallman. The ReactOS implementation was written by David Welch, Semyon Novikov, and Hermès Bélusca. Over time, alternative utilities such as tac and bat also became available, bringing different new features. Use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Scientists
Data science is an interdisciplinary academic field that uses statistics, scientific computing, scientific methods, processing, scientific visualization, algorithms and systems to extract or extrapolate knowledge from potentially noisy, structured, or unstructured data. Data science also integrates domain knowledge from the underlying application domain (e.g., natural sciences, information technology, and medicine). Data science is multifaceted and can be described as a science, a research paradigm, a research method, a discipline, a workflow, and a profession. Data science is "a concept to unify statistics, data analysis, informatics, and their related methods" to "understand and analyze actual phenomena" with data. It uses techniques and theories drawn from many fields within the context of mathematics, statistics, computer science, information science, and domain knowledge. However, data science is different from computer science and information science. Turing Award winn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uniq
uniq is a utility command on Unix, Plan 9, Inferno, and Unix-like operating systems which, when fed a text file or standard input, outputs the text with adjacent identical lines collapsed to one, unique line of text. Overview The command is a kind of filter program. Typically it is used after sort. It can also output only the duplicate lines (with the -d option), or add the number of occurrences of each line (with the -c option). For example, the following command lists the unique lines in a file, sorted by the number of times each occurs: $ sort file , uniq -c , sort -n Using uniq like this is common when building pipelines in shell scripts. History First appearing in Version 3 Unix, uniq is now available for a number of different Unix and Unix-like operating systems. It is part of the X/Open Portability Guide since issue 2 of 1987. It was inherited into the first version of POSIX and the Single Unix Specification. The version bundled in GNU coreutils was written by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tail (Unix)
is a program available on Unix, Unix-like systems, FreeDOS and MSX-DOS used to display the tail end of a text file or piped data. Implementations The version of bundled in GNU coreutils was written by Paul Rubin, David MacKenzie, Ian Lance Taylor, and Jim Meyering. The command is available as a separate package for Microsoft Windows as part of the UnxUtils collection of native Win32 ports of common GNU Unix-like utilities. The FreeDOS version was developed by M. Aitchison. A command is also part of ASCII's ''MSX-DOS2 Tools'' for MSX-DOS version 2. ''CCZE'' is -like while displaying its output in color. ''pctail'' is similar to CCZE. It is a colorized programmed in Python which tails and colorizes syslog output. ''Inotail'' was an implementation using the inotify Linux kernel interface (introduced in version 2.6.13 in August 2005) to check whether new data is available instead of polling every second, as the original did. However, newer versions of tail also started usin ... [...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. Sort ordering is affected by the environment's locale settings. 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Head (Unix)
is a program on Unix and Unix-like operating systems used to display the beginning of a text file or piped data. Syntax The command syntax is: head ptions By default, will print the first 10 lines of its input to the standard output. Option flags Other command Many early versions of Unix and Plan 9 did not have this command, and documentation and books used sed instead: sed 5q ''filename'' The example prints every line (implicit) and quits after the fifth. Equivalently, awk may be used to print the first five lines in a file: awk 'NR < 6' ''filename'' However, neither sed nor awk were available in early versions of , which were based on Version 6 Unix, and included head. Implementations Ahead command is also part of ...
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Cut (Unix)
In computing, cut is a command line utility on Unix and Unix-like operating systems which is used to extract sections from each line of input — usually from a file. It is currently part of the GNU coreutils package and the BSD Base System. Extraction of line segments can typically be done by bytes (-b), characters (-c), or fields (-f) separated by a delimiter (-d — the tab character by default). A range must be provided in each case which consists of one of N, N-M, N- (N to the end of the line), or -M (beginning of the line to M), where N and M are counted from 1 (there is no zeroth value). Since version 6, an error is thrown if you include a zeroth value. Prior to this the value was ignored and assumed to be 1. History The original Bell Labs version was written by Gottfried W. R. Luderer. is part of the X/Open Portability Guide since issue 2 of 1987. It was inherited into the first version of POSIX.1 and the Single Unix Specification. It first appeared in AT&T Syste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cat (Unix)
cat is a shell command for writing the content of a file or input stream to standard output. The name is an abbreviation of ''concatenate'' which is from the Latin ''catenare'' meaning "to chain" Originally developed for Unix, it is available on many operating systems and shells today. In addition to combining files, cat is commonly used to copy files and in particular to copy a file to the terminal monitor. Unless re-directed, outputs file content on-screen. History cat was part of the early versions of Unix, e.g., Version 1. It replaced pr, a PDP-7 and Multics command for copying a single file to the screen. It was written by Ken Thompson and Dennis Ritchie. The implementation of cat bundled in GNU coreutils was written by Torbjorn Granlund and Richard Stallman. The ReactOS implementation was written by David Welch, Semyon Novikov, and Hermès Bélusca. Over time, alternative utilities such as tac and bat also became available, bringing different new features. Use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
