File system permissions

The file permission is a term from the computer, on the basis of a system administrator in many operating systems can grant different access rights of users or groups of users to access files or directories.

This large number of different access rights to the user and / or user groups can for example be distributed across a network. A user can thus be assigned to multiple user groups, without that it is impossible that it gets its own user access within which he can freely decide about file permissions.

Classic combinable access rights for files and folders, for example, read, write, read / execute, Modify, and Full Control.

Implementations

DOS and Microsoft Windows 9x

Under DOS and old versions of Microsoft Windows, there is no file rights because it does not concern multi-user systems. The attrib command line tool that allows the user only to manipulate the file attributes, Archive, Hidden / System and Read-only.

Microsoft Windows NT

On Windows NT version 3.5 is the possibility available to use advanced file permissions, thanks to use of the NTFS file system.

Unix and its derivatives

Unix as a classic multi-user operating system has since the initial release on file permissions. Since Unix V4 (1974 ) divide these into three classes of users owner (user), group (group) and " all others " (others). For each file and folder rights read, write and execute for each of these classes can be assigned independently (see commands for user and rights management ). In addition to these file permissions, there is also still the three extended Dateirechtbits Set user identity, group identity, and set the sticky bit.

Especially newer versions of many UNIX derivatives also support if it allows the file system, and access control lists (ACLs).

VMS and OpenVMS

In the operating system VMS or OpenVMS DEC there are in addition to the classic Unix file permissions Read / write / execute even the right to delete. With the DIGITAL Command Language file permissions for file are with the statement

SET PROTECTION = (S: x G: x, O: x W: x) "file" awarded, where x is each a combination of RWED (Read, Write, Execute, Delete) is. The user groups S stands for system, G for Group, O for Owner and W World ( All other users). The privileges for a file with the command

SHOW PROTECTION "file" displayed.