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attrib
The ReactOS attrib command
Developers	Intel, IBM, Microsoft, DR, Datalight, Novell, Phil Brutsche, ReactOS Contributors
Release	1984, 41–42 years ago (DOS version)
Operating system	ISIS-II, PC DOS, MS-DOS, MSX-DOS, SISNE plus, OS/2, eComStation, ArcaOS, Windows, DR DOS, ROM-DOS, FreeDOS, ReactOS, SymbOS
Platform	Cross-platform
Type	Command
License	FreeDOS, ReactOS: GPLv2

In computing, ATTRIB is a command in Intel ISIS-II,^[1] DOS, IBM OS/2,^[2] Microsoft Windows^[3] and ReactOS^[4] that allows the user to change various characteristics, or "attributes" of a computer file or directory. The command is also available in the EFI shell.^[5]

Several operating systems provided a set of modifiable file characteristics that could be accessed and changed through a low-level system call. For example, as of release MS-DOS 4.0, the first six bits of the file attribute byte indicated whether or not a file was read-only (as opposed to writeable), hidden, a system file, a volume label, a subdirectory, or if the file had been "archived" (with the bit being set if the file had changed since the last use of the BACKUP command).^[6] However, initial releases of the operating system did not provide user-level method for reading or changing these values.^[7]

The initial version of the ATTRIB command for DOS was first included in version 3.0 of PC DOS, with functionality limited to changing the read-only attribute.^[7] Subsequent versions allowed the read-only, hidden, system and archive bits to be set.^[8] MS-DOS version 3.3 added the capability of recursive searching through subdirectories to display attributes of specified files.^[9]

Digital Research DR DOS 6.0^[10] and Datalight ROM-DOS^[11] also include an implementation of the ATTRIB command.

The FreeDOS version was developed by Phil Brutsche and is licensed under the GPLv2.^[12]

Setting the read-only bit of a file provided only partial protection against inadvertent deletion: while commands such as del and erase would respect the attribute, other commands such as DELTREE did not.^[13] Changing the system attribute was not possible in early versions of Windows, thus requiring use of ATTRIB.^[13] Similarly, a system crash in early versions of Windows could lead to a situation where a temporary file had the read-only bit set and was additionally (and irrevocably) locked by the Windows OS; in this instance, booting into DOS (thus avoiding the Windows lock) and unsetting the read-only attribute with ATTRIB was the recommended way of deleting the file.^[14] Manipulating the archive bit allowed users to control which files were backed up using the BACKUP command.^[7]

• chattr, the equivalent on Unix and Linux
• cacls, the Windows NT access control list (ACL) utility
• List of DOS commands

• Cooper, Jim (2001). Special Edition Using MS-DOS 6.22, Third Edition. Que Publishing. ISBN 978-0789725738.
• Dyson, Peter (1995). Mastering OS/2 Warp. Sybex. ISBN 978-0782116632.
• John Paul Mueller (2007). Windows Administration at the Command Line for Windows Vista, Windows 2003, Windows XP, and Windows 2000. John Wiley & Sons. ISBN 978-0470165799.

Wikibooks has a book on the topic of: Guide to Windows Commands

• attrib | Microsoft Docs
• Microsoft DOS ATTRIB command