 | This article has multiple issues. Please help improve it or discuss these issues on the talk page . (Learn how and when to remove these template messages)
|
A zero-byte file or zero-length file is a computer file containing no data; that is, it has a length or size of zero bytes. [2]
There are many ways that could manually create a zero-byte file, for example, saving empty content in a text editor, using utilities provided by operating systems, or programming to create it. On Unix-like systems, the shell command $ touch filename results in a zero-byte file filename. Zero-byte files may arise in cases where a program creates a file but aborts or is interrupted prematurely while writing to it. Because writes are cached in memory and only flushed to disk at a later time (page cache), a program that does not flush its writes to disk or terminate normally may result in a zero-byte file. When the zero-byte file is made, file system does not record the file's content on storage, but only updates its index table.
Even a file describing an empty word processor document, an image file with zero-by-zero dimensions, or an audio file of length zero seconds usually still contains metadata identifying the file format and describing some basic attributes of the file; it results in the file with some positive size. Some very simple formats do not use metadata, such as ASCII text files; these may validly be zero bytes (a common convention terminates text files with a one- or two-byte newline, however).
An empty file has a minimum disk size that depends on the disk block size, which can also be referred to as cluster size or IO block size, that depends in turn on the filesystem. This IO block size can be discovered through different utilities in the operating system, such as stat in Unix systems. [3] [4]
Zero-byte files cannot be loaded or used by most applications. In some cases, zero-byte files may be used to convey information like file metadata (for example, its filename may contain an instruction to a user viewing a directory listing such as documents-have-been-moved-to-partition-D, etc.); or to put in a directory to ensure that it is non-empty, since some tools such as backup and revision control software may ignore the empty directories.
IF Exist - Testing: Use the zero-byte (zero length) file as an "exit" ramp or for a "goto" statement within a batch-file or script. It provides a directory listing, but requires no disk space.
IF EXIST C:\NOTHING.TXT EXIT IF NOT EXIST C:\NOTHING.TXT GOTO START :START REM Create the zero-length file C:\>type null>nothing.txt :EXIT
In computing, a computer file is a resource for recording data on a computer storage device, primarily identified by its filename. Just as words can be written on paper, so can data be written to a computer file. Files can be shared with and transferred between computers and mobile devices via removable media, networks, or the Internet.
ISO 9660 is a file system for optical disc media. The file system is an international standard available from the International Organization for Standardization (ISO). Since the specification is available for anybody to purchase, implementations have been written for many operating systems.
New Technology File System (NTFS) is a proprietary journaling file system developed by Microsoft. Starting with Windows NT 3.1, it is the default file system of the Windows NT family. It superseded File Allocation Table (FAT) as the preferred filesystem on Windows and is supported in Linux and BSD as well. NTFS reading and writing support is provided using a free and open-source kernel implementation known as NTFS3 in Linux and the NTFS-3G driver in BSD. By using the convert command, Windows can convert FAT32/16/12 into NTFS without the need to rewrite all files. NTFS uses several files typically hidden from the user to store metadata about other files stored on the drive which can help improve speed and performance when reading data. Unlike FAT and High Performance File System (HPFS), NTFS supports access control lists (ACLs), filesystem encryption, transparent compression, sparse files and file system journaling. NTFS also supports shadow copy to allow backups of a system while it is running, but the functionality of the shadow copies varies between different versions of Windows.
ext3, or third extended filesystem, is a journaled file system that is commonly used by the Linux kernel. It used to be the default file system for many popular Linux distributions. Stephen Tweedie first revealed that he was working on extending ext2 in Journaling the Linux ext2fs Filesystem in a 1998 paper, and later in a February 1999 kernel mailing list posting. The filesystem was merged with the mainline Linux kernel in November 2001 from 2.4.15 onward. Its main advantage over ext2 is journaling, which improves reliability and eliminates the need to check the file system after an unclean shutdown. Its successor is ext4.
In computing, tar is a computer software utility for collecting many files into one archive file, often referred to as a tarball, for distribution or backup purposes. The name is derived from "tape archive", as it was originally developed to write data to sequential I/O devices with no file system of their own. The archive data sets created by tar contain various file system parameters, such as name, timestamps, ownership, file-access permissions, and directory organization. POSIX abandoned tar in favor of pax, yet tar sees continued widespread use.
ZIP is an archive file format that supports lossless data compression. A ZIP file may contain one or more files or directories that may have been compressed. The ZIP file format permits a number of compression algorithms, though DEFLATE is the most common. This format was originally created in 1989 and was first implemented in PKWARE, Inc.'s PKZIP utility, as a replacement for the previous ARC compression format by Thom Henderson. The ZIP format was then quickly supported by many software utilities other than PKZIP. Microsoft has included built-in ZIP support in versions of Microsoft Windows since 1998 via the "Plus! 98" addon for Windows 98. Native support was added as of the year 2000 in Windows ME. Apple has included built-in ZIP support in Mac OS X 10.3 and later. Most free operating systems have built in support for ZIP in similar manners to Windows and Mac OS X.
A filename or file name is a name used to uniquely identify a computer file in a file system. Different file systems impose different restrictions on filename lengths.
In computing, a hard link is a directory entry that associates a name with a 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 paths. This causes an alias effect: a process can open the file by any one of its paths and change its content. By contrast, a soft link or “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.
TRSDOS is the operating system for the Tandy TRS-80 line of eight-bit Zilog Z80 microcomputers that were sold through Radio Shack from 1977 through 1991. Tandy's manuals recommended that it be pronounced triss-doss. TRSDOS should not be confused with Tandy DOS, a version of MS-DOS licensed from Microsoft for Tandy's x86 line of personal computers (PCs).
dd is a command-line utility for Unix, Plan 9, Inferno, and Unix-like operating systems and beyond, the primary purpose of which is to convert and copy files. On Unix, device drivers for hardware and special device files appear in the file system just like normal files; dd can also read and/or write from/to these files, provided that function is implemented in their respective driver. As a result, dd can be used for tasks such as backing up the boot sector of a hard drive, and obtaining a fixed amount of random data. The dd program can also perform conversions on the data as it is copied, including byte order swapping and conversion to and from the ASCII and EBCDIC text encodings.
The inode is a data structure in a Unix-style file system that describes a file-system object such as a file or a directory. Each inode stores the attributes and disk block locations of the object's data. File-system object attributes may include metadata, as well as owner and permission data.
Files-11 is the file system used in the RSX-11 and OpenVMS operating systems from Digital Equipment Corporation. It supports record-oriented I/O, remote network access, and file versioning. The original ODS-1 layer is a flat file system; the ODS-2 version is a hierarchical file system, with support for access control lists,.
stat is a Unix system call that returns file attributes about an inode. The semantics of stat vary between operating systems. As an example, Unix command ls uses this system call to retrieve information on files that includes:
In computing, a file system or filesystem is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one large body of data with no way to tell where one piece of data stopped and the next began, or where any piece of data was located when it was time to retrieve it. By separating the data into pieces and giving each piece a name, the data are easily isolated and identified. Taking its name from the way a paper-based data management system is named, each group of data is called a "file". The structure and logic rules used to manage the groups of data and their names is called a "file system."
In Unix-like and some other operating systems, find is a command-line utility that locates files based on some user-specified criteria and either prints the pathname of each matched object or, if another action is requested, performs that action on each matched object.
In computer science, a sparse file is a type of computer file that attempts to use file system space more efficiently when the file itself is partially empty. This is achieved by writing brief information (metadata) representing the empty blocks to the data storage media instead of the actual "empty" space which makes up the block, thus consuming less storage space. The full block size is written to the media as the actual size only when the block contains "real" (non-empty) data.
The following tables compare general and technical information for a number of file systems.
In Unix-like operating systems, a device file or special file is an interface to a device driver that appears in a file system as if it were an ordinary file. There are also special files in DOS, OS/2, and Windows. These special files allow an application program to interact with a device by using its device driver via standard input/output system calls. Using standard system calls simplifies many programming tasks, and leads to consistent user-space I/O mechanisms regardless of device features and functions.
A file format is a standard way that information is encoded for storage in a computer file. It specifies how bits are used to encode information in a digital storage medium. File formats may be either proprietary or free.
The FAT file system is a file system used on MS-DOS and Windows 9x family of operating systems. It continues to be used on mobile devices and embedded systems, and thus is a well suited file system for data exchange between computers and devices of almost any type and age from 1981 through the present.
 | This article related to a type of software is a stub. You can help Wikipedia by expanding it. |
