SUBST is a command on the DOS, IBM OS/2 and Microsoft Windows operating systems used for substituting paths on physical and logical drives as virtual drives. It is similar to floating drives, a more general concept in operating systems of Digital Research origin, including CP/M-86 4.x, Personal CP/M-86 2.x, Concurrent DOS, Multiuser DOS , System Manager 7, REAL/32 , as well as DOS Plus and DR DOS (up to 6.0).
The Windows SUBST command is available in supported versions of the command line interpreter CMD.EXE.
In Windows NT, SUBST uses [http://msdn.microsoft.com/en-us/library/aa363904%28VS.85%29.aspx DefineDosDevice] to create the disk mappings.
In MS-DOS SUBST was added with the release of MS-DOS 3.1.
The [[JOIN (command)|JOIN]] command is the "opposite" of SUBST, because JOIN will take a drive letter and make it appear as a directory.
Some versions of MS-DOS [[COMMAND.COM]] support the undocumented internal [[TRUENAME|TRUENAME]] command which can display the "true name" of a file, i.e. the fully qualified name with drive, path, and extension, which is found possibly by name only via the PATH environment variable, or through SUBST, JOIN and [[ASSIGN (DOS command)|ASSIGN]] filesystem mappings.
Usage examples of "subst".
Charged with resisting arrest w/violence and possession of controlled subst.