what statement about controlling access to folders and files is accurate

Calculator resource

This article is almost reckoner files and file systems in full general terms. For a more than detailed and technical article, see File system.

A computer file is a figurer resources for recording information in a reckoner storage device, primarily identified by its file name. Merely as words can be written to paper, so can data be written to a computer file. Files can be shared with and transferred betwixt computers and mobile devices via removable media, networks, or the Internet.

Different types of computer files are designed for different purposes. A file may be designed to store an Image, a written message, a video, a computer plan, or any wide variety of other kinds of information. Certain files tin can shop multiple information types at once.

By using reckoner programs, a person tin can open, read, change, save, and close a calculator file. Computer files may be reopened, modified, and copied an capricious number of times.

Files are typically organized in a file system, which tracks file locations on the disk and enables user access.

Etymology [edit]

The word "file" derives from the Latin filum ("a thread").^[1]

"File" was used in the context of computer storage as early as January 1940. In Punched Carte du jour Methods in Scientific Computation,^[2] W. J. Eckert stated, "The first extensive use of the early Hollerith Tabulator in astronomy was fabricated past Comrie.^[3] He used information technology for building a table from successive differences, and for adding large numbers of harmonic terms". "Tables of functions are synthetic from their differences with swell efficiency, either as printed tables or as a file of punched cards."

In February 1950, in a Radio Corporation of America (RCA) advertising in Popular Scientific discipline magazine^[4] describing a new "memory" vacuum tube it had developed, RCA stated: "the results of countless computations can be kept 'on file' and taken out again. Such a 'file' now exists in a 'memory' tube developed at RCA Laboratories. Electronically it retains figures fed into computing machines, holds them in storage while it memorizes new ones – speeds intelligent solutions through mazes of mathematics."

In 1952, "file" denoted, amongst other things, data stored on punched cards.^[5]

In early use, the underlying hardware, rather than the contents stored on information technology, was denominated a "file". For example, the IBM 350 deejay drives were denominated "disk files".^[6] The introduction, circa 1961, by the Burroughs MCP and the MIT Uniform Time-Sharing System of the concept of a "file system" that managed several virtual "files" on one storage device is the origin of the contemporary denotation of the word. Although the gimmicky "annals file" demonstrates the early concept of files, its use has greatly decreased.

File contents [edit]

On virtually modern operating systems, files are organized into one-dimensional arrays of bytes. The format of a file is defined by its content since a file is solely a container for data.

On some platforms the format is indicated by its filename extension, specifying the rules for how the bytes must be organized and interpreted meaningfully. For instance, the bytes of a patently text file (.txt in Windows) are associated with either ASCII or UTF-viii characters, while the bytes of paradigm, video, and audio files are interpreted otherwise. Most file types as well allocate a few bytes for metadata, which allows a file to carry some bones information nearly itself.

Some file systems tin shop arbitrary (not interpreted past the file system) file-specific data exterior of the file format, just linked to the file, for instance extended attributes or forks. On other file systems this tin can be done via sidecar files or software-specific databases. All those methods, nonetheless, are more susceptible to loss of metadata than container and annal file formats.

File size [edit]

At any instant in time, a file have a size, normally expressed as number of bytes, that indicates how much storage is associated with the file. In most modern operating systems the size tin exist any non-negative whole number of bytes up to a arrangement limit. Many older operating systems kept track only of the number of blocks or tracks occupied by a file on a physical storage device. In such systems, software employed other methods to rails the exact byte count (e.m., CP/M used a special control graphic symbol, Ctrl-Z, to signal the terminate of text files).

The general definition of a file does not require that its size take any real significant, however, unless the data within the file happens to represent to data inside a puddle of persistent storage. A special case is a nothing byte file; these files can be newly created files that have not notwithstanding had whatever information written to them, or may serve as some kind of flag in the file system, or are accidents (the results of aborted disk operations). For example, the file to which the link /bin/ls points in a typical Unix-like system probably has a defined size that seldom changes. Compare this with /dev/nil which is also a file, but as a grapheme special file, its size is not meaningful.

System of data in a file [edit]

Information in a computer file can consist of smaller packets of information (oftentimes called "records" or "lines") that are individually different but share some common traits. For instance, a payroll file might contain information apropos all the employees in a visitor and their payroll details; each record in the payroll file concerns just one employee, and all the records have the common trait of being related to payroll—this is very similar to placing all payroll information into a specific filing cabinet in an office that does not accept a computer. A text file may contain lines of text, corresponding to printed lines on a piece of paper. Alternatively, a file may incorporate an capricious binary paradigm (a hulk) or it may contain an executable.

The manner information is grouped into a file is entirely up to how it is designed. This has led to a plethora of more or less standardized file structures for all imaginable purposes, from the simplest to the most complex. Near estimator files are used by computer programs which create, alter or delete the files for their ain use on an as-needed basis. The programmers who create the programs decide what files are needed, how they are to be used and (oft) their names.

In some cases, reckoner programs manipulate files that are made visible to the computer user. For example, in a word-processing program, the user manipulates document files that the user personally names. Although the content of the document file is arranged in a format that the word-processing program understands, the user is able to choose the proper noun and location of the file and provide the majority of the information (such equally words and text) that will be stored in the file.

Many applications pack all their data files into a unmarried file called an archive file, using internal markers to discern the different types of data independent within. The benefits of the annal file are to lower the number of files for easier transfer, to reduce storage usage, or just to organize outdated files. The archive file must frequently be unpacked earlier adjacent using.

Operations [edit]

The nearly basic operations that programs can perform on a file are:

• Create a new file
• Change the admission permissions and attributes of a file
• Open a file, which makes the file contents bachelor to the program
• Read information from a file
• Write information to a file
• Delete a file
• Close a file, terminating the clan betwixt it and the program
• Truncate a file, shortening it to a specified size within the file system without rewriting any content

Files on a calculator can be created, moved, modified, grown, shrunk (truncated), and deleted. In well-nigh cases, reckoner programs that are executed on the computer handle these operations, only the user of a computer can as well manipulate files if necessary. For instance, Microsoft Word files are normally created and modified by the Microsoft Word program in response to user commands, but the user can besides motility, rename, or delete these files straight by using a file manager program such equally Windows Explorer (on Windows computers) or past control lines (CLI).

In Unix-like systems, user infinite programs practise not operate directly, at a depression level, on a file. Just the kernel deals with files, and it handles all user-space interaction with files in a style that is transparent to the user-space programs. The operating system provides a level of brainchild, which means that interaction with a file from user-infinite is just through its filename (instead of its inode). For example, rm filename will not delete the file itself, merely just a link to the file. At that place can exist many links to a file, only when they are all removed, the kernel considers that file's retention space free to be reallocated. This complimentary space is unremarkably considered a security run a risk (due to the existence of file recovery software). Any secure-deletion plan uses kernel-space (arrangement) functions to wipe the file's information.

File moves inside a file system complete almost immediately considering the data content does not need to exist rewritten. Only the paths need to exist changed.

Moving methods [edit]

There are ii distinct implementations of file moves.

When moving files betwixt devices or partitions, some file managing software deletes each selected file from the source directory individually after beingness transferred, while other software deletes all files at in one case' only after every file has been transferred.

With the mv command for instance, the former method is used when selecting files individually, possibly with the use of wildcards (example: mv -n sourcePath/* targetPath, while the latter method is used when selecting entire directories (case: mv -n sourcePath targetPath). Microsoft Windows Explorer uses the former method for mass storage filemoves, but the latter method using Media Transfer Protocol, as described in Media Transfer Protocol § File move behaviour.

The former method (individual deletion from source) has the benefit that space is released from the source device or partition imminently after the transfer has begun, meaning after the first file is finished. With the latter method, space is just freed afterwards the transfer of the entire pick has finished.

If an incomplete file transfer with the latter method is aborted unexpectedly, perhaps due to an unexpected power-off, system halt or disconnection of a device, no space will have been freed up on the source device or segmentation. The user would need to merge the remaining files from the source, including the incompletely written (truncated) last file.

With the individual deletion method, the file moving software too does not demand to cumulatively keep track of all files finished transferring for the example that a user manually aborts the file transfer. A file manager using the latter (afterwards deletion) method will take to only delete the files from the source directory that accept already finished transferring.

Identifying and organizing [edit]

Files and folders bundled in a hierarchy

In modern computer systems, files are typically accessed using names (filenames). In some operating systems, the name is associated with the file itself. In others, the file is bearding, and is pointed to by links that have names. In the latter case, a user tin identify the proper name of the link with the file itself, just this is a false counterpart, specially where there exists more than i link to the same file.

Files (or links to files) can be located in directories. Withal, more by and large, a directory tin can contain either a list of files or a list of links to files. Within this definition, it is of paramount importance that the term "file" includes directories. This permits the existence of directory hierarchies, i.e., directories containing sub-directories. A name that refers to a file within a directory must be typically unique. In other words, in that location must be no identical names within a directory. However, in some operating systems, a name may include a specification of type that means a directory tin can contain an identical name for more than one blazon of object such every bit a directory and a file.

In environments in which a file is named, a file'due south name and the path to the file'due south directory must uniquely place it among all other files in the computer system—no 2 files tin can have the same name and path. Where a file is anonymous, named references to it will exist within a namespace. In most cases, any proper name inside the namespace will refer to exactly zero or i file. However, any file may exist represented within whatever namespace by zero, one or more names.

Whatsoever string of characters may be a well-formed name for a file or a link depending upon the context of application. Whether or not a name is well-formed depends on the blazon of estimator organization being used. Early computers permitted but a few letters or digits in the name of a file, but mod computers permit long names (some up to 255 characters) containing almost any combination of unicode letters or unicode digits, making it easier to empathize the purpose of a file at a glance. Some estimator systems let file names to comprise spaces; others practice not. Case-sensitivity of file names is determined by the file system. Unix file systems are unremarkably case sensitive and let user-level applications to create files whose names differ only in the case of characters. Microsoft Windows supports multiple file systems, each with different policies^{[ which? ]} regarding case-sensitivity. The common Fat file system tin accept multiple files whose names differ only in instance if the user uses a disk editor to edit the file names in the directory entries. User applications, however, will unremarkably non allow the user to create multiple files with the same name just differing in case.

Well-nigh computers organize files into hierarchies using folders, directories, or catalogs. The concept is the aforementioned irrespective of the terminology used. Each binder can contain an arbitrary number of files, and it can as well contain other folders. These other folders are referred to as subfolders. Subfolders tin comprise still more files and folders and then on, thus building a tree-like structure in which i "primary folder" (or "root folder" — the proper name varies from one operating system to some other) can contain whatever number of levels of other folders and files. Folders can be named just every bit files can (except for the root folder, which often does not have a name). The employ of folders makes it easier to organize files in a logical way.

When a estimator allows the use of folders, each file and binder has not merely a name of its own, merely also a path, which identifies the folder or folders in which a file or binder resides. In the path, some sort of special character—such as a slash—is used to separate the file and binder names. For example, in the illustration shown in this article, the path /Payroll/Salaries/Managers uniquely identifies a file called Managers in a folder called Salaries, which in turn is contained in a folder chosen Payroll. The binder and file names are separated by slashes in this case; the topmost or root folder has no name, and then the path begins with a slash (if the root folder had a proper name, information technology would precede this first slash).

Many computer systems use extensions in file names to help identify what they contain, also known as the file type. On Windows computers, extensions consist of a dot (period) at the end of a file proper name, followed by a few letters to identify the type of file. An extension of .txt identifies a text file; a .doc extension identifies any blazon of document or documentation, commonly in the Microsoft Give-and-take file format; and so on. Even when extensions are used in a computer arrangement, the degree to which the computer organization recognizes and heeds them can vary; in some systems, they are required, while in other systems, they are completely ignored if they are presented.

Protection [edit]

Many modern computer systems provide methods for protecting files against accidental and deliberate damage. Computers that allow for multiple users implement file permissions to control who may or may not modify, delete, or create files and folders. For example, a given user may be granted only permission to read a file or folder, merely not to alter or delete it; or a user may be given permission to read and modify files or folders, but not to execute them. Permissions may also exist used to allow only certain users to see the contents of a file or binder. Permissions protect confronting unauthorized tampering or destruction of data in files, and keep private information confidential from unauthorized users.

Another protection machinery implemented in many computers is a read-simply flag. When this flag is turned on for a file (which can be accomplished by a estimator program or by a man user), the file can be examined, but it cannot be modified. This flag is useful for critical information that must not be modified or erased, such as special files that are used but by internal parts of the computer arrangement. Some systems also include a hidden flag to make certain files invisible; this flag is used by the computer system to hide essential system files that users should not change.

Storage [edit]

Whatever file that has any useful purpose must have some physical manifestation. That is, a file (an abstract concept) in a real reckoner organisation must have a real concrete analogue if it is to be at all.

In concrete terms, most computer files are stored on some type of data storage device. For example, nearly operating systems store files on a hard disk. Difficult disks take been the ubiquitous form of non-volatile storage since the early 1960s.^[7] Where files contain just temporary information, they may be stored in RAM. Computer files can be besides stored on other media in some cases, such equally magnetic tapes, meaty discs, Digital Versatile Discs, Zip drives, USB flash drives, etc. The utilise of solid state drives is also beginning to rival the hd.

In Unix-like operating systems, many files take no associated concrete storage device. Examples are /dev/null and virtually files nether directories /dev, /proc and /sys. These are virtual files: they exist as objects inside the operating organization kernel.

Every bit seen past a running user plan, files are usually represented either by a file command block or by a file handle. A file command cake (FCB) is an surface area of memory which is manipulated to found a filename etc. and and then passed to the operating system every bit a parameter; information technology was used by older IBM operating systems and early PC operating systems including CP/M and early versions of MS-DOS. A file handle is by and large either an opaque information type or an integer; it was introduced in around 1961 by the ALGOL-based Burroughs MCP running on the Burroughs B5000 but is now ubiquitous.

File abuse [edit]

Corrupted JPEG file, with a unmarried fleck flipped (turned from 0 to one, or vice versa)

While at that place is visible corruption on the second file, one can still make out what the original image might have looked like.

When a file is said to be corrupted, it is because its contents have been saved to the computer in such a way that they cannot exist properly read, either past a human or by software. Depending on the extent of the damage, the original file can sometimes be recovered, or at to the lowest degree partially understood.^[8] A file may be created decadent, or information technology may exist corrupted at a afterward point through overwriting.

There are many ways by which a file can get corrupted. Most normally, the upshot happens in the procedure of writing the file to a disk.^[nine] For example, if an image-editing program unexpectedly crashes while saving an image, that file may exist corrupted because the program could not save its entirety. The program itself might warn the user that there was an error, allowing for some other attempt at saving the file.^[ten] Some other examples of reasons for which files go corrupted include:

• The calculator itself shutting down unexpectedly (for case, due to a ability loss) with open files, or files in the procedure of being saved;^{[8] [9] [10]}
• A download being interrupted before it was completed;
• Due to a bad sector on the hard drive;^{[viii] [nine]}
• The user removing a flash drive (such as a USB stick) without properly unmounting (commonly referred to as "safely removing");^{[eleven] [12] [xiii] [14]}
• Malicious software, such as a calculator virus;^{[8] [nine] [15] [16]}
• A flash drive becoming likewise old.^[14]

Although file corruption commonly happens accidentally, it may likewise be done on purpose, as to fool someone else into thinking an assignment was fix at an earlier date, potentially gaining time to end said assignment. In that location are services that provide on demand file corruption, which essentially fill a given file with random information and so that it cannot be opened or read, nevertheless withal seems legitimate.^{[17] [18]}

Ane of the most effective countermeasures for unintentional file corruption is backing upward important files.^[nineteen] In the effect of an important file becoming corrupted, the user can simply supercede it with the backed upwardly version.

Fill-in [edit]

When computer files contain information that is extremely important, a dorsum-up procedure is used to protect against disasters that might destroy the files. Backing up files simply ways making copies of the files in a separate location so that they tin exist restored if something happens to the computer, or if they are deleted accidentally.

At that place are many ways to back upwardly files. Most computer systems provide utility programs to assist in the redundancy process, which can go very fourth dimension-consuming if in that location are many files to safeguard. Files are often copied to removable media such every bit writable CDs or cartridge tapes. Copying files to another hard disk in the aforementioned reckoner protects confronting failure of i deejay, but if it is necessary to protect confronting failure or destruction of the entire reckoner, then copies of the files must be made on other media that tin be taken away from the computer and stored in a safe, distant location.

The grandfather-father-son fill-in method automatically makes three back-ups; the grandfather file is the oldest copy of the file and the son is the electric current copy.

File systems and file managers [edit]

The manner a computer organizes, names, stores and manipulates files is globally referred to as its file organisation. Most computers have at least ane file system. Some computers allow the use of several different file systems. For instance, on newer MS Windows computers, the older Fatty-blazon file systems of MS-DOS and former versions of Windows are supported, in add-on to the NTFS file system that is the normal file system for contempo versions of Windows. Each system has its ain advantages and disadvantages. Standard FAT allows only 8-graphic symbol file names (plus a three-grapheme extension) with no spaces, for example, whereas NTFS allows much longer names that can contain spaces. You can call a file "Payroll records" in NTFS, only in FAT you would be restricted to something similar payroll.dat (unless you were using VFAT, a Fatty extension assuasive long file names).

File manager programs are utility programs that permit users to dispense files directly. They allow you to motility, create, delete and rename files and folders, although they do non really allow you to read the contents of a file or store data in it. Every computer system provides at least one file-manager program for its native file system. For instance, File Explorer (formerly Windows Explorer) is commonly used in Microsoft Windows operating systems, and Nautilus is common under several distributions of Linux.

Run into also [edit]

• Block (data storage)
• Computer file direction
• Data hierarchy
• File camouflage
• File copying
• File conversion
• File deletion
• File directory
• File manager
• File organization
• Filename
• Flat-file database
• Object composition
• Soft copy

References [edit]

1. ^ "Online Etymology Dictionary". Archived from the original on 2015-09-24. Retrieved 2015-08-17 .
2. ^ Eckert, W. J.; Thomas J. Watson Astronomical Computing Bureau, New York. (1940). Punched carte methods in scientific computation. New York: The Thomas J. Watson Astronomical Calculating Bureau, Columbia University. Archived from the original on 2020-06-12. Retrieved 2018-04-17 .
3. ^ Comrie, L. J. (1928-04-thirteen). "On the Construction of Tables by Interpolation (Plate 6)". Monthly Notices of the Royal Astronomical Club. 88 (half-dozen): 506–523. Bibcode:1928MNRAS..88..506C. doi:10.1093/mnras/88.6.506. ISSN 0035-8711.
4. ^ Popular Science. Bonnier Corporation. Feb 1950. p. 96. Archived from the original on 2022-01-09. Retrieved 2014-03-07 .
5. ^ Robert South. Casey, et al. Punched Cards: Their Applications to Science and Manufacture. 1952.
6. ^ Martin H. Weik. Ballistic Research Laboratories Study #1115. March 1961. pp. 314–331 Archived 2016-x-21 at the Wayback Machine.
7. ^ Magnetic Storage Handbook 2nd Ed., Section 2.one.1, Deejay File Technology, Mee and Daniel, (c)1990,
8. ^ ^{a b c d} Gorski, Victoria. "What Causes a Corrupt File?". Archived from the original on 2020-07-28. Retrieved 2019-03-17 .
9. ^ ^{a b c d} Williams, Jane (2019-01-fourteen). "What Does It Hateful When Your File Is Decadent?". Houston Chronicle. Archived from the original on 2019-07-fifteen. Retrieved 2019-03-17 .
10. ^ ^{a b} Glenn, Walter (2017-12-fourteen). "What Is a Corrupted File, and Is There a Style to Get It Back?". How-To Geek. Archived from the original on 2018-12-06. Retrieved 2019-03-17 .
11. ^ "What Causes Flash Memory Abuse?". SecureDataRecovery. Archived from the original on 2020-07-28. Retrieved 2019-03-17 .
12. ^ Hoffman, Chris (2016-09-28). "Do Y'all Really Demand to Safely Remove USB Flash Drives?". How-To Geek. Archived from the original on 2019-03-thirty. Retrieved 2019-03-17 .
13. ^ "Open up a document afterwards a file corruption error". Microsoft Office Support. Archived from the original on 2019-08-28. Retrieved 2019-03-17 .
14. ^ ^{a b} "What kills your Flash Bulldoze and how you can avoid information technology". DataRecovery.cyberspace. Archived from the original on 2018-09-06. Retrieved 2019-03-17 .
15. ^ Neagoe, Robert (2018-08-xiv). "Fix Windows ten File Corruption Issues". Windowsreport.com. Archived from the original on 2020-07-28. Retrieved 2019-03-17 .
16. ^ International Council of Electronic Commerce Consultants (2009-09-24). "Mac Os Ten Hacking". Ethical Hacking and Countermeasures: Linux, Macintosh and Mobile Systems. Cengage. pp. two.6–ii.seven. ISBN978-i-4354-8364-four. Archived from the original on 2020-07-29. Retrieved 2019-03-17 .
17. ^ "Corrupt a file - Corrupt file online, deliver on fourth dimension!". Archived from the original on 2019-03-23. Retrieved 2019-03-17 .
18. ^ "Corrupt My File: Get your file corrupted for you". Archived from the original on 2019-03-15. Retrieved 2019-03-17 .
19. ^ "What is a Corrupted File?". Intego. 2019-03-07. Archived from the original on 2020-07-28. Retrieved 2019-03-17 .

External links [edit]

• Media related to Estimator files at Wikimedia Commons
• Data Formats Reckoner file at Curlie

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Source: https://en.wikipedia.org/wiki/Computer_file

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