HP NonStop G-Series - Manual (Page 195)

extended data
segment An area of virtual memory used to contain data.
feature-test macro A symbol that, if defined in a program’s source code, includes specific other symbols from a
header within that program’s source code and makes those symbols visible.
field. An addressable entry within a data structure. The term “field” is sometimes used to mean
“member.”
FIFO special file. See FIFO. .
FIFO. A type of special file that is always read and written in a first-in, first-out manner.
file class. The property of a file indicating access permissions for a process related to the owner, group,
or other identification of the process.
See also
file group class , file other class , file owner class. .
file description. See open file description. .
file descriptor. The nonnegative integer that uniquely identifies a single open of a file to a running process. Each
file descriptor is associated with an open file description that contains data about the file.
file group class The property of a file indicating access permissions for a process related to the group identification
of the process. A process is in the file group class of a file if both of the following are true:
•
The process is not a member of the file owner class.
•
The process has an effective group ID or supplementary group ID that matches the group
ID associated with the file.
file identifier. In the Guardian environment, the portion of a filename following the subvolume name. In the
Open System Services (OSS) environment, a portion of the internal information used to identify
a file in the OSS file system. The two identifiers are not comparable.
file link count. The total number of directory entries for a file within a HP NonStop node.
file mode creation
mask. A mask associated with a process. When a process creates a file, bits set in this mask are cleared
in the access permission bits for the file.
file mode. A field in the stat structure for a specific file that describes the type and characteristics of the
file and contains the access permission bits for the file.
file other class The property of a file indicating access permissions for a process related to the user and group
IDs of the process. A process is in the file other class of a file if both of the following are true:
•
The process is not a member of the file owner class for the file.
•
The process is not a member of the file group class for the file.
file owner class. The property of a file indicating access permissions for a process related to the user ID of the
process. A process is in the file owner class of a file if the process has an effective user ID that
is the same as the user ID (owner) of the file.
file permission bits. Information about a file that is used, along with other information, to determine whether a process
or user has read, write, or execute/search permission to that file. The bits are divided into three
parts: owner, group, and other. Each part is used with the corresponding file class of processes.
file serial number. A number that uniquely identifies a file within its file system.
file system In the Open System Services (OSS) environment, a collection of files and file attributes. A file
system provides the namespace for the file serial numbers that uniquely identify its files. Open
System Services provides a file system (see also ISO/IEC IS 9945-1: 1990 [ANSI/IEEE Std.
1003.1-1990], Clause 2.2.2.38); the Guardian application program interface (API) provides a
file system; and OSS Network File System (NFS) provides a file system. (OSS NFS filenames and
pathnames are governed by slightly different rules than OSS filenames and pathnames.) Within
the OSS and OSS NFS file systems, filesets exist as manageable objects.
On a HP NonStop system, the Guardian file system for a node is a subset of the OSS virtual file
system. Traditionally, the API for file access in the Guardian environment is referred to as the
“Guardian file system.”
In some UNIX and NFS implementations, the term “file system” is used to mean the same thing
as “fileset.” That is, a file system is a logical grouping of files that, except for the root of the file
system, can be contained only by directories within the file system.
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