E
ed editor
A line-oriented program for modifying the contents of text files. The program
operates by accepting commands from the user; for example, issuing the
command s/Unix/UNIX/g would cause the editor to replace each instance of the
string "Unix" on the current line with "UNIX."
editor
A program for modifying the contents of text files. Full-screen editors, such as vi,
use video display terminals to display several lines of the file being manipulated;
they allow the user to move the cursor to a specific location and change the text
there. Line editors, such as ed, work on a line-by-line basis. Stream editors, such
as sed, work by applying commands from a previously prepared list (called a
script) instead of by accepting commands from the user.
effective root directory
The point where a system starts when searching for a file. Its pathname begins
with a slash (/).
effective user ID
The current user ID, but not necessarily the user's ID. For example, a user logged
in under a login ID may change to another user's ID. The ID to which the user
changes becomes the effective user ID until the user switches back to the original
login ID.
EGP (External Gateway Protocol)
A type of routing protocol that allows individual networks to communicate with
the Internet backbone.
See also Internet
Emacs
A text editor developed by the Free Software Foundation that is available for all
UNIX systems, although it is not a standard part of Berkeley UNIX or System V. It
is included with the DIGITAL UNIX operating system.
environment
The set of conditions under which a user is working on the computer. The
environment includes such information as the name of the working directory, the
name of the command interpreter, the identity of the user's terminal, and so on.
environment variable
A symbol containing information that can be used by shells or commands.
Environment variables are available to all processes in a given process group;
they are propagated by the creation of a child process.
See also process variable
EOF (end of file)
1. A condition indicating that the end of a data file has been reached by a
program reading the file.
2. A specific sequence of characters written on a magnetic tape.
See also BOM, file mark
equivalence class
A grouping of characters or character strings that are considered equal for
purposes of collation. For example, many languages place an uppercase
character in the same equivalence class as its lowercase form, but some
languages distinguish between accented and unaccented character forms for the
purpose of collation.
error
Any condition in which the expected results of an operation are not achieved. In
XTI, an indicator that is returned by a function when it encounters a system or
library error in the process of executing. The object is to allow applications to take
an action based on the returned error code.
escape
1. To protect a character from interpretation by a program by preceding it with a
backslash (\).
2. An ASCII character that is usually interpreted as a command to cease a certain
activity or as the initial character of a sequence that performs a special function.
Cursor control sequences for many terminals and workstations use the escape
character.
See also quote
/etc
A catchall directory, which usually contains miscellaneous system data files (such
as termcap, the terminal capabilities database).
Ethernet
A communications concept for local communication networks that interconnects
different kinds of computers, information processing products, and office
equipment. It is a 10-megabit-per-second baseband local area network (LAN)
using carrier sense multiple access with collision detection (CSMA/CD). The
network allows multiple stations to access the medium at will without prior
coordination, and avoids contention by using carrier sense and deference, and
detection and transmission.
ETSDU
TBS
See also expedited data, out-of-band data
Expedited Transport Service Data Unit
See ETSDU
event
An occurrence, or happening, that is significant to a transport user. Events are
asynchronous, in that they do not happen as a result of an action taken by the
user.
event executable image
An executable image located in physical memory.
event management
A mechanism by which transport providers notify transport users of the
occurrence of significant events.
executable file
A data file created by a compiler that contains program information a computer
can read, interpret, and execute. Also called an image or a binary file.
ex editor
A line-oriented program for modifying the contents of text files. The ex editor is
an extended version of the ed editor.
expedited data
Data that is considered urgent. The semantics of this data are defined by the
transport provider.
See also out-of-band data
expression
1. A representation of a value; for example, variables and constants appearing
alone or in combination with operators.
2. In programming languages, a language construct for computing a value from
one or more operands, such as literals, identifiers, array references, and function
calls.
3. A configuration of signs.
extended character
A character other than a 7-bit ASCII character. An extended character can be a 1-
byte code point with the eighth bit set (ordinal 128-255).
External Gateway Protocol
See EGP (External Gateway Protocol)
