File attribute

As file attributes or file properties generally additional information is a file called, which go beyond the content - so-called metadata . In particular - if folders or directories are meant (see also directory structure ) - these properties are also called folder properties (or folder attributes ).

more details

Display of the file properties of multiple files under Windows XP; some of the attributes are displayed in the form of checkboxes and can be changed using these.

In addition to the mere content of a file, file systems must also store additional information about it, such as: B. Storage location, access rights or time of the last change. Some operating systems (such as macOS ) have a much more extensive metadata concept and thus support e.g. This includes, for example, the storage of file type-specific information (e.g. last cursor position for text files, information on the author of music files, etc.). However, since most Unix systems still only provide a very limited amount of metadata, or this has not yet been standardized (across operating systems and file systems), one is moving towards accommodating data of this type directly in the contents of the files (e.g. B. ID3 tags in MP3 files).

Examples of metadata

• Name of the file (in file systems that support multiple names per file, e.g. NTFS ; in other file systems, file names belong to the content of a directory, e.g. FAT )
• Type of file (e.g. device files under Posix , under Windows directories have an attribute that identifies them as a directory)
• Type of file content (this can be regulated via a file extension as part of the name or via a special storage area such as HFS under classic Mac OS and its successor macOS )
• Date and, if applicable, time
  • the creation of the file content
  • The creation of the file ( This Copy Created , under Windows creation ) is sometimes equated with the creation of the file content
  • of the last write access to the file (under Posix mtime , under Windows Last Write )
  • the change in the file content is sometimes equated with the last write access to the file, since before a write access is usually not checked whether the content actually changes
  • changing the metadata of the file (under Posix ctime )
  • of the last access to the file (under Posix atime , under Windows Last Access ), under Windows this information also records changes to metadata such as file attributes
  • the last time the file was archived (e.g. with HFS, ZFS and UDF )
  • the expiration of the file ( expiration date on z / OS )
• File size
• File permissions in the form of Unix file rights or access control lists , including the storage of the owner and the owner group
• Identification of the file (for FAT, NTFS and HPFS ) as:
  • File to be archived (with A, for [ English ] archive )
  • read-only file (with R, for read only , literally read only )
  • hidden file (withHfor hidden )
  • "[ Operating ] system file" (with Sfor system )
• Extended attributes (for NTFS, HPFS and Ext2 ) for storing any additional information, for example under Windows a file is marked with a certain extended attribute if it comes from the Internet
• Comment fields , some operating systems even support voice recordings as comments,
• Labels ( keywords ), i.e. assignments for specific purposes ( work , urgent , etc., under Mac OS)
• Record length, record format, block size (with z / OS)
• Marking the file as encrypted and security descriptors for accessing it (with EFS )
• In addition, information about mechanisms for saving storage space can count as attributes if it is not already recorded as an extended attribute, e.g. B. transparent compression (with NTFS) or sparse files

Single receipts

Individual receipts and comments:

1. ↑ 7.4.4: Folder properties - Magnum, Windows Vista Business , Markt-und-Technik-Verlag , 2007, ISBN 978-3-8272-4090-3 , p. 402.
2. ↑ ... compare, for example, Windows with FAT and NTFS on the one hand AND Linux with ext4 and btrfs on the other