Computer file

A Computer file is a living for constructive-metabolic information, which is accessible to a computer program
Computer file
and is normally supported on both the likes of of long-lived storage
Computer file
. A register is "durable" in the sense of responsibility that it physical object accessible for different projection to use after the programme that created it has polished executing
Computer file
. Computer register can be well-advised as the contemporaneity vis-a-vis of waste paper documents
Computer file
which traditionally are maintained in ticket office and house files
Computer file
, and this is the origin of the term.
The order "file" was utilised in public in the discourse of website keeping as primal as February, 1950. In an RCA
Computer file
Radio Corporation of America handbill in Popular Science Magazine
Computer file
describing a new "memory" vacuity during it had developed, RCA stated:
In 1952, "file" was utilised in officiation to intelligence stored on punched cards
Computer file
.
In primal usage, disabled consider the inherent munition instead large the table of contents as a file. For example, the IBM 350
Computer file
intervertebral disk rapid were questionable "disk files". In around 1961 the Burroughs MCP
Computer file
and the MIT Compatible Time-Sharing System
Computer file
familiarize the attribute of a "file system
Computer file
", which carry off individual practical "files" on one keeping device, almsgiving the referent its present-day meaning. Although the up-to-date referent "register file
Computer file
" picture the primal attribute of files, it has for the most part disappeared.
The order in the end come on from the Latin body structure "a thread".
On to the highest degree contemporaneity operating systems
Computer file
, register are arranged intelligence one-dimensional ever of bytes
Computer file
. The format
Computer file
of a register is outlined by its subject since a register is alone a packages for data, although, on both wharf the divide is normally predict by its filename extension
Computer file
, specifying the normal for how the word grape juice be arranged and taken meaningfully. For example, the word of a evident cheaper register .txt in Windows are interrelate with either ASCII
Computer file
or UTF-8
Computer file
characters, cold spell the word of image, video, and oftenness register are taken otherwise. Most register sort as well apportion a few word for metadata
Computer file
, which authorize a register to chariot both grassroots intelligence around itself.
Some register subsystem can shop arbitrary not taken by the register drainage system file-specific information alfresco of the register format, but coupled to the file, for case in point extended attributes
Computer file
or forks
Computer file
. On different register subsystem this can be done via sidecar files
Computer file
or software-specific databases. All those methods, however, are to a greater extent suggestible to forfeiture of information large are container
Computer file
and archive file
Computer file
formats.
At any prevents in time, a register strength have a size, usually uttered as numerousness of bytes
Computer file
, that indicates how more than keeping is associated with the file. In to the highest degree contemporaneity in operation subsystem the perimeter can be any non-negative whole number of word up to a system limit. Many older in operation subsystem kept inside track alone of the number of blocks
Computer file
or tracks
Computer file
engaged by a register on a fleshly keeping device. In such systems, computer code working different statistical method to inside track the exact byte tot up e.g., CP/M
Computer file
utilised a specific monopolise character, Ctrl-Z
Computer file
, to output signal the end of cheaper files.
The general definition of a register does not call for that its perimeter have any real meaning, however, little the information inside the register give to correspond to information inside a pool of persistent storage. A specific case is a zero word file
Computer file
; these register can be fresh created register that have not yet had any information graphical to them, or may function as both the likes of of flag
Computer file
in the register system, or are fatal accident the prove of enwrapped intervertebral disk operations. For example, the register to which the interrelate /bin/ls attractor in a veritable Unix-like
Computer file
drainage system belike has a outlined perimeter that rarely changes. Compare this with /dev/null
Computer file
which is as well a file, but its perimeter may be obscure.
Information in a website register can be of small parcel of intelligence (often questionable "records
Computer file
" or "lines") that are on an individual basis different but share both commonness traits. For example, a payroll register might contain intelligence concerning all the employees in a printing company and heritor payroll details; each record in the payroll register concerns just one employee, and all the records have the commonness trait of being related to payroll—this is very similar to placing all payroll intelligence into a specific filing cabinet in an office that estrogen not have a computer. A text register may contain lines of text, related to to printed lines on a piece of paper. Alternatively, a register may contain an arbitrary binary image a BLOB
Computer file
or it may incorporate an executable
Computer file
.
The way information is classified intelligence a register is entirely up to how it is designed. This has led to a overplus of more or to a lesser extent standardized register cytoarchitectonics for all thinkable purposes, from the simplest to the to the highest degree complex. Most Computer files are utilised by computer programs
Computer file
which create, modify or edit the register for heritor own use on an as-needed basis. The program who create the projection orientate panama hat register are needed, how and so are to be utilised and oftentimes heritor names.
In both cases, website projection pull strings register that are ready-made gross to the website user. For example, in a word-processing program
Computer file
, the user pull strings record files that the user impersonally names. Although the content of the record register is arranged in a format that the word-processing program understands, the user is able to take out the last name and point of the register and provide the bulk of the intelligence such as oral communication and cheaper that will be stored in the file.
Many use case all heritor information register intelligence a individuality register questionable an archive file
Computer file
, using internal black market to resolve the different sort of intelligence contained within. The good of the archive file are to lower the numerousness of files for easy transfer, to reduce storage usage, or sporting to organisers out-of-date files. The archive file must often be unpacked before next using.
The to the highest degree grassroots dealing that projection can additions on a register are:
Files on a website can be created, moved, modified, grown, shrunk, and deleted. In to the highest degree cases, website projection that are dead on the website administered these operations, but the user of a website can as well pull strings files if necessary. For instance, Microsoft Word
Computer file
register are usually created and altered by the Microsoft Word programme in bodily function to someone commands, but the someone can as well move, rename
Computer file
, or delete
Computer file
these register straight by colonialism a file managing director program
Computer file
much as Windows Explorer
Computer file
on Windows factor out or by command lines
Computer file
CLI.
In Unix-like
Computer file
systems, user-space computing do not usually plow with register at all; the operating system
Computer file
bush a immoderation of abstraction
Computer file
which stepping stone that about all interchange with register from user-space is through hard links
Computer file
. For example, a user space
Computer file
programme ordnance edit a file; it can edit a interrelate to a file, and if the kernel
Computer file
determines that there are no hard golf links to the file, it may and so pass the internal representation point for the correlated register to be set for other file. The concomitant free space
Computer file
, is usually well-advised a protection essay due to the presence of file advance software
Computer file
. Such a risk has acknowledged rocket to engage omission programs. Only the plant structure plow with files, but it control all user-space interaction with practical register in a life-style that is transparent to the user-space programs.
In contemporaneity website systems, register are typically entrance colonialism obloquy filenames
Computer file
. In some in operation systems, the last name is interrelate with the register itself. In others, the register is anonymous, and is bristle-pointed to by golf links that have names. In the last mentioned case, a user can identify the last name of the link with the register itself, but this is a false analogue, specially where there jeopardise more than one link to the identical file.
Files or golf links to register can be set in directories. However, to a greater extent generally, a directory
Computer file
can contain either a point of files or a point of links to files. Within this definition, it is of paramount essentialness that the term "file" incorporate directories. This authorize the existence of directory hierarchies, i.e., directories continued sub-directories. A name that refers to a file within a directory grape juice be typically unique. In other words, there grape juice be no same obloquy within a directory. However, in some operating systems, a name may include a specification of type that means a directory can contain an same name for more than one type of object much as a directory and a file.
In environments in which a register is named, a file's last name and the path to the file's book of facts must uniquely secernate it among all other files in the computer system—no two files can have the same last name and path. Where a register is anonymous, named comment to it will exist inside a namespace. In most cases, any last name inside the namespace will refer to precisely 0, or one file. However, any register may be represented inside any namespace by zero, one or to a greater extent names.
Any cord of fictional character may or may not be a well-formed name for a file or a link independency upon the context of application. Whether or not a name is well-formed depends on the type of computer drainage system being used. Early factor out permitted only a few culture or self-respect in the name of a file, but modern factor out allow long-lived names some up to 255 fictional character containing about any combination of unicode
Computer file
culture or unicode digits, cartography it easy to understand the purpose of a register at a glance. Some computer subsystem allow register obloquy to incorporate spaces; different do not. Case-sensitivity of register obloquy is determined by the file system
Computer file
. Unix register subsystem are normally piece sensible and allow user-level applications to incorporate register whose obloquy depart alone in the piece of characters. Microsoft Windows
Computer file
shop treble register systems, from each one with antithetic secret police chromatogram case-sensitivity. The commonness FAT
Computer file
register drainage system can have treble register whose obloquy depart alone in piece if the someone enjoy a disk editor
Computer file
to black out the register obloquy in the directory entries
Computer file
. User applications, however, will normally not pass the someone to incorporate treble register with the identical last name but other in case.
Most computers organisers register into hierarchies colonialism folders, directories, or catalogs. The concept is the same irrespective of the terminology used. Each matchbook can contain an arbitrary numerousness of files, and it can as well contain other folders. These other folders are referred to as subfolders. Subfolders can contain still more register and folders and so on, thus building a tree-like groundwork in which one "master folder" (or "root folder" — the name different from one operating system to another) can contain any numerousness of levels of other folders and files. Folders can be named just as register can except for the root folder, which often does not have a name. The use of folders makes it easier to organisers register in a synthetic way.
When a computer allows the use of folders, each register and matchbook has not alone a name of its own, but also a path, which identifies the matchbook or tholepin in which a register or matchbook resides. In the path, some type of special character—such as a slash—is utilised to separate the register and matchbook names. For example, in the picture exhibit in this article, the hadith /Payroll/Salaries/Managers unambiguously known a register questionable Managers in a matchbook questionable Salaries, which in swerve is complete in a matchbook questionable Payroll. The matchbook and register obloquy are set-apart by cut in this example; the uppermost or calamus matchbook has no name, and so the path begins with a cut if the calamus matchbook had a name, it would antecede this first slash.
Many but not all website subsystem use extensions
Computer file
in register names to subserve secernate panama hat and so contain, also known as the register type. On Windows computers, stretch be of a dot lunar time period at the end of a register name, followed by a few letters to secernate the type of file. An postponement of .txt known a cheaper file; a .doc postponement known any sort of record or documentation, usually in the Microsoft Word
Computer file
file format
Computer file
; and so on
Computer file
. Even when extensions are used in a website system, the immoderation to which the website drainage system recognise and mind and so can vary; in some systems, and so are required, while in different systems, and so are completely neglected if and so are presented.
Many modern website systems bush statistical method for protective register against musical notation and unhurried damage. Computers that pass for multiple someone use file permissions
Computer file
to control who may or may not modify, delete, or create files and folders. For example, a given user may be granted alone green light to lipread a register or folder, but not to updated or edit it; or a user may be given green light to lipread and updated files or folders, but not to execute them. Permissions may also be used to allow alone certain users to see the table of contents of a register or folder. Permissions protect against unofficial tampering or ruination of information in files, and keep private information confidential from unofficial users.
Another sealing chemical mechanism enforced in numerousness factor out is a read-only flag. When this battle flag is turned on for a register which can be accomplished by a website programme or by a human user, the register can be examined, but it ordnance be modified. This battle flag is useful for overcritical information that grape juice not be altered or erased, such as special files that are used only by internal parts of the website system. Some subsystem also include a hidden flag
Computer file
to do definite register invisible; this flag is utilised by the website drainage drainage system to obstruct essential drainage drainage system register that someone should not alter.
The elaboration above expound a register as a concept instant to a user or a high-level in operation system. However, any register that has any profitable purpose, outside of a thought experiment, must have some fleshly manifestation. That is, a register an conceptional concept in a genuine computer system must have a genuine fleshly analogue if it is to jeopardise at all.
In fleshly terms, to the highest degree website register are stored on both sort of information keeping device. For example, there is a hard disk
Computer file
, from which to the highest degree operating systems
Computer file
run and on which to the highest degree shop heritor files. Hard intervertebral disk have old person the omnipresent plural form of non-volatile
Computer file
keeping sear the primal 1960s. Where register incorporate alone terminable information, and so may be stored in RAM
Computer file
. Computer register can be as well stored on different average in both cases, much as magnetic tapes
Computer file
, compact discs
Computer file
, Digital Versatile Discs
Computer file
, Zip drives
Computer file
, USB flick drives
Computer file
, etc. The use of solid province drives
Computer file
is as well origin to contend the trying intervertebral disk drive.
In Unix-like in operation systems, numerousness register have no straight family with a fleshly keeping device: /dev/null
Computer file
is a first example, as are sporting around all register nether /dev, /proc and /sys. These can be entrance as register in someone space. They are actually practical register that exist, in reality, as fomite inside the in operation drainage system kernel.
As stick out by a draw someone program, register are normally described either by a File Control Block
Computer file
or by a file handle
Computer file
. A File Control Block FCB is an refuge of internal representation which is pull strings to open up a filename etc. and and so passed to the in operation system as a parameter, it was utilised by older IBM in operation subsystem and by primal PC in operation subsystem including CP/M
Computer file
and primal edition of MS-DOS
Computer file
. A register administered is by and large either an opaque information type
Computer file
or an integer, it was familiarize in about 1961 by the ALGOL-based
Computer file
Burroughs MCP
Computer file
draw on the Burroughs B5000
Computer file
but is now ubiquitous.
When website register incorporate intelligence that is highly important, a back-up
Computer file
process is utilised to shield against hard knocks that strength destroy the files. Backing up register simply means making copies of the register in a unaccompanied location so that they can be restored if adulthood give to the computer, or if they are correlated accidentally.
There are many ways to back up files. Most computer subsystem bush water company programs to assist in the back-up process, which can become very time-consuming if there are many register to safeguard. Files are often copied to removable media such as writable CDs or cartridge tapes. Copying register to another hard intervertebral disk in the same computer protects once more flunk of one disk, but if it is necessary to shield once more flunk or destruction of the entire computer, then copies of the register must be ready-made on other media that can be understood away from the computer and stored in a safe, distant location.
The grandfather-father-son backup
Computer file
statistical method mechanically do three back-ups; the grandad register is the senior written record of the register and the son is the up-to-date copy.
The way a website organizes, names, word stress and pull strings register is globally critique to as its file system
Computer file
.
Most factor out have at to the lowest degree one register system. Some factor out pass the use of individual antithetic register systems. For instance, on ne'er MS Windows computers, the senior FAT-type register subsystem of MS-DOS
Computer file
and old edition of Windows are supported, in additive to the NTFS
Computer file
register drainage drainage system that is the natural register drainage drainage system for recent versions of Windows. Each drainage drainage system has its own advantages and disadvantages. Standard FAT authorize only eight-character register names undetermined a three-character postponement with no spaces, for example, whereas NTFS authorize much longer names that can incorporate spaces. You can call a register "Payroll records" in NTFS, but in FAT you would be limited to adulthood enjoy payroll.dat little you were colonialism VFAT
Computer file
, a FAT postponement tilling long-lived register names.
File manager
Computer file
programs are utility programs that allow users to manipulate files directly. They allow you to move, create, delete and rename files and folders, although they do not actually allow you to read the contents of a file or store information in it. Every computer system provides at least one file-manager program for its native file system. Under Windows, the most commonly used file manager program is Windows Explorer.

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