R = Read-Only: Most software, when seeing a file marked read-only, will refuse to delete or modify it. This is pretty straight-forward. For example, DOS will say "Access denied" if you try to delete a read-only file. On the other hand, Windows Explorer will happily munch it. Some will choose the middle ground: they will let you modify or delete the file, but only after asking for confirmation. Show
H = Hidden: This one is pretty self-explanatory as well; if the file is marked hidden then under normal circumstances it is hidden from view. DOS will not display the file when you type "DIR" unless a special flag is used, as shown in the earlier example. S = System: This flag is used to tag important files that are used by the system and should not be altered or removed from the disk. In essence, this is like a "more serious" read-only flag and is for the most part treated in this manner. It is also a "super-hidden" attribute. Even if you enable “Show hidden files”, system files will not be displayed. (You can display them by disabling “Hide protected operating system files.”) D = Directory: This is the bit that differentiates between entries that describe files and those that describe subdirectories within the current directory. In theory you can convert a file to a directory by changing this bit. Of course in practice, trying to do this would result in a mess--the entry for a directory has to be in a specific format. A = Archive: This is a special bit that is used as a "communications link" between software applications that modify files, and those that are used for backup. Most backup software allows the user to do an incremental backup, which only selects for backup any files that have changed since the last backup. This bit is used for this purpose. When the backup software backs up ("archives") the file, it clears the archive bit (makes it zero). Any software that modifies the file subsequently, is supposed to set the archive bit. Then, the next time that the backup software is run, it knows by looking at the archive bits which files have been modified, and therefore which need to be backed up. Again, this use of the bit is "voluntary"; the backup software relies on other software to use the archive bit properly; some programs could modify the file without setting the archive attribute, but fortunately most software is "well-behaved" and uses the bit properly. Still, you should not rely on this mechanism absolutely to ensure that your critical files are backed up. Source Missing from the above list: C = Compressed: compressed files/folder cannot be encrypted. E = Encrypted: encrypted files/folders cannot be compressed. N = NOT INDEXED L = Reparse Points O = OFFLINE P = Sparse File I = Not content indexed T = TEMPORARY Combinations are possible, e.g., HSA = Hidden, System, Archive Extended file attributes are file system features that enable users to associate computer files with metadata not interpreted by the filesystem, whereas regular attributes have a purpose strictly defined by the filesystem (such as permissions or records of creation and modification times). Unlike forks, which can usually be as large as the maximum file size, extended attributes are usually limited in size to a value significantly smaller than the maximum file size. Typical uses include storing the author of a document, the character encoding of a plain-text document, or a checksum, cryptographic hash or digital certificate, and discretionary access control information. In Unix-like systems, extended attributes are usually abbreviated as xattr.[1] Implementations[edit]AIX[edit]In AIX, the JFS2 v2 filesystem supports extended attributes, which are accessible using the getea command.[2] The getea,[3] setea,[4] listea,[5] statea,[6] and removeea[7] APIs support fetching, setting, listing, getting information about, and removing extended attributes. BeOS/Haiku[edit]In the now-defunct BeOS and successors like Haiku, extended file attributes are widely used in base and third-party programs. The Be File System allows the indexing and querying of attributes, essentially giving the filesystem database-like characteristics. The uses of extended attributes in Be-like systems are varied: For example, Tracker and OpenTracker, the file-managers of BeOS and Haiku respectively, both store the locations of file icons in attributes,[8] Haiku's "Mail" service stores all message content and metadata in extended file attributes,[9] and the MIME types of files are stored in their attributes. Extended file attributes can be viewed and edited in Be-like systems' GUI through the file-manager, often Tracker or derivatives thereof. FreeBSD[edit]In FreeBSD 5.0 and later, the UFS1, UFS2, and ZFS filesystems support extended attributes, using the extattr_[10] family of system calls. Any regular file may have a list of extended attributes. Each attribute consists of a name and the associated data. The name must be a null-terminated string, and exists in a namespace identified by a small-integer namespace identifier. Currently, two namespaces exist: user and system. The user namespace has no restrictions with regard to naming or contents. The system namespace is primarily used by the kernel for access control lists and mandatory access control. Linux[edit]In Linux, the ext2, ext3, ext4, JFS, Squashfs, UBIFS, Yaffs2, ReiserFS, Reiser4, XFS, Btrfs, OrangeFS, Lustre, OCFS2 1.6, ZFS, and F2FS[11] filesystems support extended attributes (abbreviated xattr) when enabled in the kernel configuration. Any regular file or directory may have extended attributes consisting of a name and associated data. The name must be a null-terminated string prefixed by a namespace identifier and a dot character. Currently, four namespaces exist: user, trusted, security and system. The user namespace has no restrictions with regard to naming or contents. The system namespace is primarily used by the kernel for access control lists. The security namespace is used by SELinux, for example. Support for the extended attribute concept from a POSIX.1e draft[citation needed] that had been withdrawn in 1997 was added to Linux around 2002.[12][13] As of 2016, they are not yet in widespread use by user-space Linux programs, but are used by Beagle, OpenStack Swift, Dropbox, KDE's semantic metadata framework (Baloo), Chromium, Wget and cURL. The Linux kernel allows extended attribute to have names of up to 255 bytes and values of up to 64 KiB,[14] as do XFS and ReiserFS, but ext2/3/4 and btrfs impose much smaller limits, requiring all the attributes (names and values) of one file to fit in one "filesystem block" (usually 4 KiB). Per POSIX.1e,[citation needed] the names are required to start with one of security, system, trusted, and user plus a period. This defines the four namespaces of extended attributes.[15] Extended attributes can be accessed and modified using the macOS[edit]Mac OS X 10.4 and later support extended attributes by making use of the HFS+ filesystem Attributes File B*-tree feature which allows for named forks. Although the named forks in HFS+ support arbitrarily large amounts of data through extents, the OS support for extended attributes only supports inline attributes, limiting their size to that which can fit within a single B*-tree node.[citation needed] Any regular file may have a list of extended attributes. HFS+ supports an arbitrary number of named forks, and it is unknown if macOS imposes any limit on the number of extended attributes. Each attribute consists of a name and the associated data. The name is a null-terminated Unicode string. No namespace restrictions are present (making this an open xattr system) and the convention is to use a reverse DNS string (similar to Uniform Type Identifiers) as the attribute name. macOS supports listing,[17] getting,[18] setting,[19] and removing[20] extended attributes from files or directories using a Linux-like API. From the command line, these abilities are exposed through the xattr utility.[21] Since macOS 10.5, files originating from the web are marked with OpenBSD[edit]Support for extended file attributes was removed from the OpenBSD source code in 2005 due to a lack of interest in Access Control Lists.[23] OS/2[edit]In OS/2 version 1.2 and later, the High Performance
File System was designed with extended attributes in mind, but support for them was also retro-fitted on the FAT filesystem of DOS. For compatibility with other operating systems using a FAT partition, OS/2 attributes are stored inside a single file " Parts of OS/2 version 2.0 and later such as the Workplace Shell uses several standardized extended attributes (also called EAs) for purposes like identifying the filetype, comments, computer icons and keywords about the file. Programs written in the interpreted language Rexx store an already parsed version of the code as an extended attribute, to allow faster execution. Solaris[edit]Solaris version 9 and later allows files to have "extended attributes", which are actually forks; the maximum size of an "extended attribute" is the same as the maximum size of a file, and they are read and written in the same fashion as files. Internally, they are actually stored and accessed like normal files, so their names cannot contain "/" characters[25] and their ownership and permissions can differ from those of the parent file. Version 4 of the Network File System supports extended attributes in much the same way as Solaris. Windows NT[edit]On Windows NT, limited-length extended attributes are supported by FAT,[24] HPFS, and NTFS. This was implemented as part of the OS/2 subsystem. They are notably used by the NFS server of the Interix POSIX subsystem in order to implement Unix-like permissions. The Windows Subsystem for Linux added in the Windows 10 Anniversary Update uses them for similar purposes, storing the Linux file mode, owner, device ID (if applicable), and file times in the extended attributes.[26] Additionally, NTFS can store arbitrary-length extended attributes in the form of alternate data streams (ADS), a type of resource fork. Plugins for the file manager Total Commander, like NTFS Descriptions and QuickSearch eXtended support filtering the file list by or searching for metadata contained in ADS.[27][28] NTFS-3G supports mapping ADS to extended attributes in FUSE; it also maps file attributes that way.[29] See also[edit]
References[edit]
Which file attribute identifies the file as having been modified since the last backup?B.
Attribute Archive identifies that a file's metadata has been modified since the last backup. This attribute is assigned automatically. All (used only for the Clear option) represents all attributes that can be modified. Archive identifies files that have modified content since the last backup.
Which file attribute identifies the file?A file's attributes vary from one OS to another but typically consist of these: Name. Identifier. This unique tag, usually a number, identifies the file within the file system; it is the non-human-readable name for the file.
What are 4 common file attributes for Windows?File attributes are maintained in the file system's directories, and typical attributes are Read-Only, Hidden, System and Archive.
Which three attributes can be set when using the attrib command select three?The ATTRIB command lets you view, set, or clear attributes for any file, group of files, or subdirectory.
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