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Temporary Filesystem
tmpfs (short for Temporary File System) is a temporary file storage paradigm implemented in many Unix-like operating systems. It is intended to appear as a mounted file system, but data is stored in volatile memory instead of a persistent storage device. The idea behind tmpfs is similar in concept to a RAM disk, in that both provide a file system stored in volatile memory; however, the implementations are different. While tmpfs is implemented at the ''logical file system'' layer, a RAM disk is implemented at the ''File system#Architecture, physical file system'' layer. In other words, a RAM disk is a virtual block device with a normal file system running on top of it, while tmpfs is a virtual file system without any underlying block device. Semantics Everything stored in tmpfs is temporary in the sense that no files will be directly created on non-volatile storage such as a hard drive (although swap space is used as backing store according to the page replacement policy of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temporary File
A temporary file is a file created to store information temporarily, either for a program's intermediate use or for transfer to a permanent file when complete. It may be created by computer programs for a variety of purposes, such as when a program cannot allocate enough memory for its tasks, when the program is working on data bigger than the architecture's address space, or as a primitive form of inter-process communication. Auxiliary memory Modern operating systems employ virtual memory, however programs that use large amounts of data (e.g. Video editing software, video) may need to create temporary file(s). Inter-process communication Most operating systems offer primitives such as Pipeline (software), pipes, Internet socket, sockets or Shared memory (interprocess communication), shared memory to pass data among programs, but often the simplest way (especially for programs that follow the Unix philosophy) is to write data into a temporary file and inform the receiving prog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix Domain Sockets
A Unix domain socket (UDS), a.k.a. local socket, a.k.a. inter-process communication (IPC) socket, is a communication endpoint for exchanging data between processes executing in the same Unix or Unix-like operating system. The name, ''Unix domain socket'', refers to the domain argument value AF_UNIX that is passed to the function that creates a socket system resource. The same communication domain is also selected by AF_LOCAL. Valid type argument values for a UDS are: * SOCK_STREAM (compare to TCP) – for a stream-oriented socket * SOCK_DGRAM (compare to UDP) – for a datagram-oriented socket that preserves message boundaries (as on most UNIX implementations, UNIX domain datagram sockets are always reliable and don't reorder datagrams) * SOCK_SEQPACKET (compare to SCTP) – for a sequenced-packet socket that is connection-oriented, preserves message boundaries, and delivers messages in the order that they were sent The UDS facility is a standard component of a POSIX operating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DragonFly BSD
DragonFly BSD is a free and open-source Unix-like operating system forked from FreeBSD 4.8. Matthew Dillon, an Amiga developer in the late 1980s and early 1990s and FreeBSD developer between 1994 and 2003, began working on DragonFly BSD in June 2003 and announced it on the FreeBSD mailing lists on 16 July 2003. Dillon started DragonFly in the belief that the techniques adopted for threading and symmetric multiprocessing in FreeBSD 5 would lead to poor performance and maintenance problems. He sought to correct these anticipated problems within the FreeBSD project. Due to conflicts with other FreeBSD developers over the implementation of his ideas, his ability to directly change the codebase was eventually revoked. Despite this, the DragonFly BSD and FreeBSD projects still work together, sharing bug fixes, driver updates, and other improvements. Dillon named the project after photographing a dragonfly in his yard, while he was still working on FreeBSD. Intended as the log ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FreeBSD
FreeBSD is a free-software Unix-like operating system descended from the Berkeley Software Distribution (BSD). The first version was released in 1993 developed from 386BSD, one of the first fully functional and free Unix clones on affordable home-class hardware, and has since continuously been the most commonly used BSD-derived operating system. FreeBSD maintains a complete system, delivering a kernel, device drivers, userland utilities, and documentation, as opposed to Linux only delivering a kernel and drivers, and relying on third-parties such as GNU for system software. The FreeBSD source code is generally released under a permissive BSD license, as opposed to the copyleft GPL used by Linux. The project includes a security team overseeing all software shipped in the base distribution. Third-party applications may be installed using the pkg package management system or from source via FreeBSD Ports. The project is supported and promoted by the FreeBSD Foundation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NetBSD
NetBSD is a free and open-source Unix-like operating system based on the Berkeley Software Distribution (BSD). It was the first open-source BSD descendant officially released after 386BSD was fork (software development), forked. It continues to be actively developed and is available for many platforms, including servers, desktops, handheld devices, and embedded systems. The NetBSD project focuses on code clarity, careful design, and portability across many computer architectures. Its source code is publicly available and Permissive free software licence, permissively licensed. History NetBSD was originally derived from the 4.3BSD-Reno release of the Berkeley Software Distribution from the Computer Systems Research Group of the University of California, Berkeley, via its Net/2 source code release and the 386BSD project. The NetBSD project began as a result of frustration within the 386BSD developer community with the pace and direction of the operating system's development. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix File System
The Unix file system (UFS) is a family of file systems supported by many Unix and Unix-like operating systems. It is a distant descendant of the original filesystem used by Version 7 Unix. Design A UFS volume is composed of the following parts: * A few blocks at the beginning of the partition reserved for boot blocks (which must be initialized separately from the filesystem) * A superblock, containing a magic number identifying this as a UFS filesystem, and some other vital numbers describing this filesystem's geometry and statistics and behavioral tuning parameters * A collection of cylinder groups. Each cylinder group has the following components: ** A backup copy of the superblock ** A cylinder group header, with statistics, free lists, etc., about this cylinder group, similar to those in the superblock ** A number of inodes, each containing file attributes ** A number of data blocks Inodes are numbered sequentially, starting at 0. Inode 0 is reserved for unalloc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berkeley Software Distribution
The Berkeley Software Distribution (BSD), also known as Berkeley Unix or BSD Unix, is a discontinued Unix operating system developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berkeley, beginning in 1978. It began as an improved derivative of AT&T's original Unix that was developed at Bell Labs, based on the source code but over time diverging into its own code. BSD would become a pioneer in the advancement of Unix and computing. BSD's development was begun initially by Bill Joy, who added virtual memory capability to Unix running on a VAX-11 computer. In the 1980s, BSD was widely adopted by workstation vendors in the form of proprietary Unix distributions such as DEC Ultrix and Sun Microsystems SunOS due to its permissive licensing and familiarity to many technology company founders and engineers. It also became the most popular Unix at universities, where it was used for the study of operating systems. BSD was sponsored ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel
Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine learning * Kernelization, a technique for designing efficient algorithms ** Kernel, a routine that is executed in a vectorized loop, for example in general-purpose computing on graphics processing units *KERNAL, the Commodore operating system Mathematics Objects * Kernel (algebra), a general concept that includes: ** Kernel (linear algebra) or null space, a set of vectors mapped to the zero vector ** Kernel (category theory), a generalization of the kernel of a homomorphism ** Kernel (set theory), an equivalence relation: partition by image under a function ** Difference kernel, a binary equalizer: the kernel of the difference of two functions Functions * Kernel (geometry), the set of points within a polygon from which the whole polygon boundary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Out Of Memory
Out of memory (OOM) is an often undesired state of computer operation where no additional memory can be allocated for use by programs or the operating system. Such a system will be unable to load any additional programs, and since many programs may load additional data into memory during execution, these will cease to function correctly. This usually occurs because all available memory, including disk swap space, has been allocated. History Historically, the out-of-memory condition was more common than it is now, since early computers and operating systems were limited to small amounts of physical random-access memory (RAM) due to the inability of early processors to address large amounts of memory, as well as cost considerations. Since the advent of virtual memory opened the door for the usage of swap space, the condition is less frequent. Almost all modern programs expect to be able to allocate and deallocate memory freely at run-time, and tend to fail in uncontrolled ways ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Page Cache
In computing, a page cache, sometimes also called disk cache, is a transparent cache for the pages originating from a secondary storage device such as a hard disk drive (HDD) or a solid-state drive (SSD). The operating system keeps a page cache in otherwise unused portions of the main memory (RAM), resulting in quicker access to the contents of cached pages and overall performance improvements. A page cache is implemented in kernels with the paging memory management, and is mostly transparent to applications. Usually, all physical memory not directly allocated to applications is used by the operating system for the page cache. Since the memory would otherwise be idle and is easily reclaimed when applications request it, there is generally no associated performance penalty and the operating system might even report such memory as "free" or "available". When compared to main memory, hard disk drive read/writes are slow and random accesses require expensive disk seeks; as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel
The Linux kernel is a Free and open-source software, free and open source Unix-like kernel (operating system), kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the kernel for the GNU operating system (OS) which was created to be a free software, free replacement for Unix. Since the late 1990s, it has been included in many Linux distributions, operating system distributions, many of which are called Linux. One such Linux kernel operating system is Android (operating system), Android which is used in many mobile and embedded devices. Most of the kernel code is written in C (programming language), C as supported by the GNU compiler collection (GCC) which has extensions beyond standard C. The code also contains assembly language, assembly code for architecture-specific logic such as optimizing memory use and task execution. The kernel has a Modular programming, modular design such that modules can be inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solaris (operating System)
Oracle Solaris is a proprietary software, proprietary Unix operating system offered by Oracle Corporation, Oracle for SPARC and x86-64 based workstations and server (computing), servers. Originally developed by Sun Microsystems as Solaris, it superseded the company's earlier SunOS in 1993 and became known for its scalability, especially on SPARC systems, and for originating many innovative features such as DTrace, ZFS and Time Slider. After the Acquisition of Sun Microsystems by Oracle Corporation, Sun acquisition by Oracle in 2010, it was renamed Oracle Solaris. Solaris was registered as compliant with the Single UNIX Specification until April 29, 2019. Historically, Solaris was developed as proprietary software. In June 2005, Sun Microsystems released most of the codebase under the CDDL license, and founded the OpenSolaris Open-source software, open-source project. Sun aimed to build a developer and user community with OpenSolaris; after the Oracle acquisition in 2010, the Open ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
