D
daemon
A process that performs a system management function that is transparent to
the user. A daemon can perform its task automatically or periodically. For
example, the cron daemon periodically performs the tasks listed in the crontab
file. Daemons can be generated by the system and by applications. Some
daemons can also be started manually; for example, the binlogd command starts
a daemon that logs binary event records to specified files. The commands that
manually start daemons usually end with a d.
data communications
The transmission of information between computers by means of a network such
as an Ethernet, a telephone system, or a satellite link.
datagram
A unit of data that is transmitted across a network by the connectionless service
of a transport provider. In addition to user data, a datagram includes the
information needed for its delivery. It is self-contained, in that it has no
relationship to any datagrams previously or subsequently transmitted.
datagram socket
A socket that provides datagrams consisting of individual messages for
transmission in connectionless mode.
Dataless Management Services
See DMS (Dataless Management Services)
dbxd
The command that invokes the dbx program, which is used by developers to help
debug other programs under development.
DCE (Distributed Computing Environment)
A defacto standard for distributed computing that defines a uniform set of
services that share certain global properties for common naming, security, time
synchronization, system availability, access to data, and system management.
DCE enables applications and data on heterogeneous systems to work together.
delta
In an RCS or SCCS file, the set of changes that constitute a specific version of the
file.
dependency file
See dependent
dependency subset
The condition in which a subset may or may not require the presence of other
subsets in order to function properly. Evaluated by a subset's software control
program (SCP) under control of the setld utility.
See also SCP (Subset Control Program), subset
dependent
Also called a dependency file. In the make utility, an entity on which a file to be
built (the target) depends. A source file is a dependent of an object module.
detached job
A job that continues processing after the user has logged out.
device driver
The software that controls a peripheral device such as a disk or a printer.
device special file
A file used by processes to access hardware devices. For example, a printer is
accessed through a device special file.
See also block special file
DFS (Distributed File System)
A distributed DCE application that provides a unified, globally distributed file
system. Under this file system, a DFS file is accessible from any DCE DFS machine
using the same name, regardless of the server currently storing the file.
DHCP (Dynamic Host Configuration Protocol)
An Internet (TCP/IP) Protocol that enables the automatic assignment of Internet
addresses to clients on the network from a pool of reusable addresses. Address
assignment occurs automatically whenever client systems such as portable
computers are attached to the network.
directory
A type of file containing the names and controlling information for other files or
other directories.
directory hierarchy
The arrangement of directories in a file system. The root directory is at the top of
the directory hierarchy and contains pointers to all file systems and all directories
on the system.
directory stack
A data structure that stores directories for later recall.
disk label
The disk information, usually located in sector 0 (zero), that includes the disk
geometry and partition divisions. This information is used by the system disk
driver and the boot program to identify a drive, and to determine how to
program a drive and where to find the file systems.
See also geometry, partition
disk partition
See partition
Distributed Computing Environment
See DCE (Distributed Computing Environment)
Distributed File System
See DFS (Distributed File System)
DMS (Dataless Management Services)
A service provided by DIGITAL whereby a server computer system maintains the
root, /usr, and /var file systems for client computer systems connected to the
server via a local area network (LAN).
See also LAN (Local Area Network)
DMS area
A reserved disk area that is physically connected to a DMS server and that
contains multiple copies of the DMS root area, one for each DMS client.
DMS client
A computer system whose system disk area is physically connected to a DMS
server rather than to the client itself and is accessed across the network by the
client.
domain
See domain name system
domain name system
A tree-structured system for organizing hosts names for an entire internet.
See also communication domain, Internet domain name system
down time
The period during which a machine is unavailable for use.
See also up time
Dynamic Host Configuration Protocol
See DHCP (Dynamic Host Configuration Protocol)
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