Fully qualified file name - AbsoluteAstronomy.com

The term fully qualified file name means a file on a computer whose exact name is completely specified such that it is unambiguous and cannot be mistaken for any other file on that system. It is somewhat equivalent on the Internet to a URL specifying the full name of the computer and the entire name of a particular document as a file. The alternative is an unqualified file name or a partially qualified file name.

On Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...

-style systems, DOS
DOS
DOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...

, and Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

, the name "sample" refers to a file in the current directory named "sample". If the current directory is changed, then the file referred to by the name "sample" is different. If you start the filename with "/" indicating the root directory
Root directory
In computer file systems, the root directory is the first or top-most directory in a hierarchy. It can be likened to the root of a tree — the starting point where all branches originate.-Metaphor:...

as in "/Users/Name/sample", then on Unix this is a fully qualified file name. In DOS, this is still relative to the root directory of the current disk
Drive letter assignment
Drive letter assignment is the process of assigning alphabetical identifiers to physical or logical disk drives or partitions in the root filesystem namespace; this usage is now mostly found in Microsoft operating systems...

, to get a fully qualified file name, one must prefix the file name with the drive letter and a colon, as in "C:\Users\Name\sample", where "C:" specifies the "C" drive.
Also on the above systems, some programs such as the command-line shell will search a path
Path (computing)
A path, the general form of a filename or of a directory name, specifies a unique location in a file system. A path points to a file system location by following the directory tree hierarchy expressed in a string of characters in which path components, separated by a delimiting character, represent...

for a file. Inserting a leading (back)slash, as in "./name", will stop the searching of the path. This is a partially qualified name, but not a fully qualified name as it still depends on the current directory. A fully qualified name, because it contains (back)slashes, will always stop a path search.
On the mainframe
Mainframe computer
Mainframes are powerful computers used primarily by corporate and governmental organizations for critical applications, bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.The term originally referred to the...

operating system MUSIC/SP
MUSIC/SP
MUSIC/SP was developed at McGill University in the 1970s from an early IBM time-sharing system called RAX...

, if one asks for the file name "X", one is making an unqualified reference either to the file X in the user's library, or to the file X in the common library if the user does not have a file named X and one does exist in the common library. If, however, one were to refer to "*COM:X" one is using a fully qualified file name reference to the file X in the common library even if they have a different file named X in their library. Similarly, a reference to "*USR:X" would mean the file in their own library, and "MA45:X" would be a fully qualified file name referring to the specific file X in the library of user MA45.
On the RSTS/E
RSTS/E
RSTS is a multi-user time-sharing operating system, developed by Digital Equipment Corporation , for the PDP-11 series of 16-bit minicomputers. The first version of RSTS was implemented in 1970 by DEC software engineers that developed the TSS-8 time-sharing operating system for the PDP-8...

operating system on the PDP-11
PDP-11
The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 replaced the PDP-8 in many real-time applications, although both product lines lived in parallel for more than 10 years...

minicomputer, specifying a file "X.X" would refer to a file in one's own directory. Referring to "$X.X" would be referring to the file "[1,2]X.X" but to fully qualify the file name, one would have to indicate the device, so "SY:[46,145]MYFILE.TXT", "SY:$X.X", or "SY:[1,2]X.X" (the last two examples meaning the same thing) would be a fully qualified file name under RSTS/E.
On the Univac 90/60
UNIVAC 90/60
The Univac 90/60 series computer was a mainframe class computer manufactured by Sperry Corporation as a competitor to the IBM System 360 series of mainframe computers...

mainframe operating system VS/9
VS/9
VS/9 was a computer operating system available for the Univac 90/60, 90/70 and 90/80 mainframe during the late 1960s through 1980s. The 90/60 and 90/70 were repackaged Univac 9700 computers...

, specifying a file "X" could mean either the file X in the account of that user, or could mean the file X in the library of the system manager, $TSOS. However, specifying "$S0103.X" would be a fully qualified file name.
This term can also include the case where one prefixes a fully qualified file name with a specific computer name as a prefix to a file name (where the particular system permits referencing a file on another system), so long as the exact name is unambiguous.

See also