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Unlink (Unix)
In Unix-like operating systems, unlink is a system call and a command line utility to delete files. The program directly interfaces the system call, which removes the file name and (but not on GNU systems) directories like rm and rmdir. If the file name was the last hard link to the file, the file itself is deleted as soon as no program has it open. Unlike the rm utility, the unlink utility only accepts one argument, which can be desirable to guard against accidental multi-deletions. It also appears in the PHP, Node.js, R, Perl and Python standard libraries in the form of the ''unlink()'' built-in function. Like the Unix utility, it is also used to delete files. Examples To delete a file named ''foo'', one could type: % unlink foo In PHP, one could use the following function to do the same: unlink("foo"); The Perl syntax is identical to the PHP syntax, save for the parentheses: unlink "foo"; In Node.js it is almost the same as the others: fs.unlink("foo", callb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix
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 allows U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Node
In general, a node is a localized swelling (a "knot") or a point of intersection (a vertex). Node may refer to: In mathematics * Vertex (graph theory), a vertex in a mathematical graph *Vertex (geometry), a point where two or more curves, lines, or edges meet. * Node (autonomous system), behaviour for an ordinary differential equation near a critical point * Singular point of an algebraic variety, a type of singular point of a curve In science and engineering Spherical geometry * node, the points where a great circle crosses a plane of reference, or the equator of a sphere Astronomy * Orbital node, the points where an orbit crosses a plane of reference ** Lunar node, where the orbits of the Sun and Moon intersect ** Longitude of the ascending node, how orbital nodes are parameterized Biology * Lymph node, an immune system organ used to store white blood cells * Node of Ranvier, periodic gaps in the insulating myelin sheaths of myelinated axons *Sinoatrial node and atrioven ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ln (Unix)
is a shell command for creating a link file to an existing file or directory. By default, the command creates a hard link, but with the command line option, it creates a symbolic link. Most systems disallow a hard link to a directory since such links could disrupt the structure of a file system and interfere with the operation of other utilities. The command can create a symbolic link to non-existent file. The command appeared in Issue 2 of the X/Open Portability Guidelines. The version in GNU Core Utilities was written by Mike Parker and David MacKenzie. The command is available in Windows via UnxUtils and has been ported to IBM i. Links A link allows more than one path to refer to the same file. A hard link is a directory entry that refers to a file's inode (an internal reference). A file can have multiple hard links each referring to the same inode. Creating a hard link does not copy the contents of the file; but merely causes another name to be associated with the sam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Link (Unix)
The link utility is a Unix command line program that creates a hard link from an existing directory entry to a new directory entry. It does no more than call the ''link()'' system function. It does not perform error checking before attempting to create the link. It returns an exit status that indicates whether the link was created (0 if successful, -1 if an error occurred). Creating a link to a directory entry that is itself a directory requires elevated privileges. The '' ln'' command is more commonly used as it provides more features: it can create both hard links and symbolic links, and has error checking. Synopsis link (-s) source target ;source: The pathname of an existing folder or file. ;target: The name of the link to be created. Note that source must specify an existing folder or file, and target must specify a non-existent entry in an existing directory. Standards The link command is part of the Single UNIX Specification (SUS), specified in the ''Shell and Utili ... [...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] |
S (programming Language)
S is a statistical programming language developed primarily by John Chambers (statistician), John Chambers and (in earlier versions) Rick Becker, Trevor Hastie, William S. Cleveland, William Cleveland and Allan Wilks of Bell Labs, Bell Laboratories. The aim of the language, as expressed by John Chambers, is "to turn ideas into software, quickly and faithfully". It was formerly widely used by academic researchers., but has now been superseded by the partially backwards compatible R (programming language), R language, a part of the GNU free software project. S-PLUS was a widely used commercial implementation of S that was formerly sold by TIBCO Software. History "Old S" S is one of several statistical computing languages that were designed at Bell Laboratories, and first took form between 1975–1976. Up to that time, much of the statistical computing was done by directly calling Fortran subroutines; however, S was designed to offer an alternate and more interactive approach, moti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Python (programming Language)
Python is a high-level programming language, high-level, general-purpose programming language. Its design philosophy emphasizes code readability with the use of significant indentation. Python is type system#DYNAMIC, dynamically type-checked and garbage collection (computer science), garbage-collected. It supports multiple programming paradigms, including structured programming, structured (particularly procedural programming, procedural), object-oriented and functional programming. It is often described as a "batteries included" language due to its comprehensive standard library. Guido van Rossum began working on Python in the late 1980s as a successor to the ABC (programming language), ABC programming language, and he first released it in 1991 as Python 0.9.0. Python 2.0 was released in 2000. Python 3.0, released in 2008, was a major revision not completely backward-compatible with earlier versions. Python 2.7.18, released in 2020, was the last release of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perl
Perl is a high-level, general-purpose, interpreted, dynamic programming language. Though Perl is not officially an acronym, there are various backronyms in use, including "Practical Extraction and Reporting Language". Perl was developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions. Perl originally was not capitalized and the name was changed to being capitalized by the time Perl 4 was released. The latest release is Perl 5, first released in 1994. From 2000 to October 2019 a sixth version of Perl was in development; the sixth version's name was changed to Raku. Both languages continue to be developed independently by different development teams which liberally borrow ideas from each other. Perl borrows features from other programming languages including C, sh, AWK, and sed. It provides text processing facilities without the arbitrary data-length limits of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
R (programming Language)
R is a programming language for statistical computing and Data and information visualization, data visualization. It has been widely adopted in the fields of data mining, bioinformatics, data analysis, and data science. The core R language is extended by a large number of R package, software packages, which contain Reusability, reusable code, documentation, and sample data. Some of the most popular R packages are in the tidyverse collection, which enhances functionality for visualizing, transforming, and modelling data, as well as improves the ease of programming (according to the authors and users). R is free and open-source software distributed under the GNU General Public License. The language is implemented primarily in C (programming language), C, Fortran, and Self-hosting (compilers), R itself. Preprocessor, Precompiled executables are available for the major operating systems (including Linux, MacOS, and Microsoft Windows). Its core is an interpreted language with a na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rm (Unix)
rm, short for remove, is a shell command for removing files (which includes special files such as directories) from the file system. The command may not actually delete a file (release its storage for reuse) since it only unlinks it removes a hard link to a file via the unlink() system call. If a file has multiple links and less than all are removed, then the file remains in the file system; accessible via its other links. When a file's only link is removed, then the file is deleted releasing its storage space for other use. Generally, a deleted file's former storage space still contains the file's data until it is overwritten with another file's content. The data is not accessible via normal file operations but can be recovered via specialized tools. Since this is considered a security risk in some contexts, a hardened version of may wipe the file's storage area when the file is deleted. Commands such as shred and srm specifically provide data wiping. Since rm does no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix-like
A Unix-like (sometimes referred to as UN*X, *nix 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 software, application is one that behaves like the corresponding List of POSIX commands, Unix command or Unix shell, shell. Although there are general Unix philosophy, 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, FreeBSD and OpenBSD. These systems are often used on servers as well as on personal computers and other devices. Many popular applications, such as the Apache HTTP Server, Apache web server and the Bash (Unix shell), Bash shell, are also designed to be used on Unix-like systems. Definition The Open ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hard Link
In computing, a hard link is a directory entry (in a Directory (computing), directory-based file system) that associates a name with a Computer file, file. Thus, each file must have at least one hard link. Creating additional hard links for a file makes the contents of that file accessible via additional Path (computing), paths (i.e., via different names or in different directories). This causes an Aliasing (computing), alias effect: a process can open the file by any one of its paths and change its content. By contrast, a soft link or File shortcut, “shortcut” to a file is not a direct link to the data itself, but rather a reference to a hard link or another soft link. Every directory is itself a special file on many systems, containing a list of file names instead of other data. Hence, multiple hard links to directories are possible, which could create a circular directory structure, rather than a branching structure like a Tree structure, tree. For that reason, some file sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
