xbd_chap03.html

IEEE 1003.1-2003, Single Unix Specification v3

be sent to all processes in the process group associated with the controlling terminal. <basefont size="2"></p>

<dl>
<dt><b>Note:</b></dt>

<dd>The General Terminal Interface is defined in detail in <a href="xbd_chap11.html#tag_11"><i>General Terminal Interface</i></a>
.</dd>
</dl>

<basefont size="3"> 

<h3><a name="tag_03_115"></a>Conversion Descriptor</h3>

<p>A per-process unique value used to identify an open codeset conversion.</p>

<h3><a name="tag_03_116"></a>Core File</h3>

<p>A file of unspecified format that may be generated when a process terminates abnormally.</p>

<h3><a name="tag_03_117"></a>CPU Time (Execution Time)</h3>

<p>The time spent executing a process or thread, including the time spent executing system services on behalf of that process or
thread. If the Threads option is supported, then the value of the CPU-time clock for a process is implementation-defined. With this
definition the sum of all the execution times of all the threads in a process might not equal the process execution time, even in a
single-threaded process, because implementations may differ in how they account for time during context switches or for other
reasons.</p>

<h3><a name="tag_03_118"></a>CPU-Time Clock</h3>

<p>A clock that measures the execution time of a particular process or thread.</p>

<h3><a name="tag_03_119"></a>CPU-Time Timer</h3>

<p>A timer attached to a CPU-time clock.</p>

<h3><a name="tag_03_120"></a>Current Job</h3>

<p>In the context of job control, the job that will be used as the default for the <a href="../utilities/fg.html"><i>fg</i></a> or
<a href="../utilities/bg.html"><i>bg</i></a> utilities. There is at most one current job; see also <a href="#tag_03_203">Job
Control Job ID</a> .</p>

<h3><a name="tag_03_121"></a>Current Working Directory</h3>

<p>See <i>Working Directory</i> in <a href="#tag_03_436">Working Directory (or Current Working Directory)</a> .</p>

<h3><a name="tag_03_122"></a>Cursor Position</h3>

<p>The line and column position on the screen denoted by the terminal's cursor.</p>

<h3><a name="tag_03_123"></a>Datagram</h3>

<p>A unit of data transferred from one endpoint to another in connectionless mode service.</p>

<h3><a name="tag_03_124"></a>Data Segment</h3>

<p>Memory associated with a process, that can contain dynamically allocated data.</p>

<h3><a name="tag_03_125"></a>Deferred Batch Service</h3>

<p>A service that is performed as a result of events that are asynchronous with respect to requests. <basefont size="2"></p>

<dl>
<dt><b>Note:</b></dt>

<dd>Once a batch job has been created, it is subject to deferred services.</dd>
</dl>

<basefont size="3"> 

<h3><a name="tag_03_126"></a>Device</h3>

<p>A computer peripheral or an object that appears to the application as such.</p>

<h3><a name="tag_03_127"></a>Device ID</h3>

<p>A non-negative integer used to identify a device.</p>

<h3><a name="tag_03_128"></a>Directory</h3>

<p>A file that contains directory entries. No two directory entries in the same directory have the same name.</p>

<h3><a name="tag_03_129"></a>Directory Entry (or Link)</h3>

<p>An object that associates a filename with a file. Several directory entries can associate names with the same file.</p>

<h3><a name="tag_03_130"></a>Directory Stream</h3>

<p>A sequence of all the directory entries in a particular directory. An open directory stream may be implemented using a file
descriptor.</p>

<h3><a name="tag_03_131"></a>Disarm (a Timer)</h3>

<p>To stop a timer from measuring the passage of time, disabling any future process notifications (until the timer is armed
again).</p>

<h3><a name="tag_03_132"></a>Display</h3>

<p>To output to the user's terminal. If the output is not directed to a terminal, the results are undefined.</p>

<h3><a name="tag_03_133"></a>Display Line</h3>

<p>A line of text on a physical device or an emulation thereof. Such a line will have a maximum number of characters which can be
presented. <basefont size="2"></p>

<dl>
<dt><b>Note:</b></dt>

<dd>This may also be written as &quot;line on the display&quot;.</dd>
</dl>

<basefont size="3"> 

<h3><a name="tag_03_134"></a>Dollar Sign</h3>

<p>The character <tt>'$'</tt> .</p>

<h3><a name="tag_03_135"></a>Dot</h3>

<p>In the context of naming files, the filename consisting of a single dot character ( <tt>'.'</tt> ). <basefont size="2"></p>

<dl>
<dt><b>Note:</b></dt>

<dd>In the context of shell special built-in utilities, see <a href="../utilities/dot.html"><i>dot</i></a> in the Shell
and Utilities volume of IEEE&nbsp;Std&nbsp;1003.1-2001, <a href="../utilities/xcu_chap02.html#tag_02_14">Section 2.14, Special
Built-In Utilities</a>. 

<p>Pathname Resolution is defined in detail in <a href="xbd_chap04.html#tag_04_11"><i>Pathname Resolution</i></a> .</p>
</dd>
</dl>

<basefont size="3"> 

<h3><a name="tag_03_136"></a>Dot-Dot</h3>

<p>The filename consisting solely of two dot characters ( <tt>".."</tt> ). <basefont size="2"></p>

<dl>
<dt><b>Note:</b></dt>

<dd>Pathname Resolution is defined in detail in <a href="xbd_chap04.html#tag_04_11"><i>Pathname Resolution</i></a> .</dd>
</dl>

<basefont size="3"> 

<h3><a name="tag_03_137"></a>Double-Quote</h3>

<p>The character <tt>' ,'</tt> also known as quotation-mark. <basefont size="2"></p>

<dl>
<dt><b>Note:</b></dt>

<dd>The &quot;double&quot; adjective in this term refers to the two strokes in the character glyph. IEEE&nbsp;Std&nbsp;1003.1-2001 never
uses the term &quot;double-quote&quot; to refer to two apostrophes or quotation marks.</dd>
</dl>

<basefont size="3"> 

<h3><a name="tag_03_138"></a>Downshifting</h3>

<p>The conversion of an uppercase character that has a single-character lowercase representation into this lowercase
representation.</p>

<h3><a name="tag_03_139"></a>Driver</h3>

<p>A module that controls data transferred to and received from devices. <basefont size="2"></p>

<dl>
<dt><b>Note:</b></dt>

<dd>Drivers are traditionally written to be a part of the system implementation, although they are frequently written separately
from the writing of the implementation. A driver may contain processor-specific code, and therefore be non-portable.</dd>
</dl>

<basefont size="3"> 

<h3><a name="tag_03_140"></a>Effective Group ID</h3>

<p>An attribute of a process that is used in determining various permissions, including file access permissions; see also <a href=
"#tag_03_188">Group ID</a> .</p>

<h3><a name="tag_03_141"></a>Effective User ID</h3>

<p>An attribute of a process that is used in determining various permissions, including file access permissions; see also <a href=
"#tag_03_425">User ID</a> .</p>

<h3><a name="tag_03_142"></a>Eight-Bit Transparency</h3>

<p>The ability of a software component to process 8-bit characters without modifying or utilizing any part of the character in a
way that is inconsistent with the rules of the current coded character set.</p>

<h3><a name="tag_03_143"></a>Empty Directory</h3>

<p>A directory that contains, at most, directory entries for dot and dot-dot, and has exactly one link to it, in dot-dot. No other
links to the directory may exist. It is unspecified whether an implementation can ever consider the root directory to be empty.</p>

<h3><a name="tag_03_144"></a>Empty Line</h3>

<p>A line consisting of only a &lt;newline&gt;; see also <a href="#tag_03_75">Blank Line</a> .</p>

<h3><a name="tag_03_145"></a>Empty String (or Null String)</h3>

<p>A string whose first byte is a null byte.</p>

<h3><a name="tag_03_146"></a>Empty Wide-Character String</h3>

<p>A wide-character string whose first element is a null wide-character code.</p>

<h3><a name="tag_03_147"></a>Encoding Rule</h3>

<p>The rules used to convert between wide-character codes and multi-byte character codes. <basefont size="2"></p>

<dl>
<dt><b>Note:</b></dt>

<dd>Stream Orientation and Encoding Rules are defined in detail in the System Interfaces volume of IEEE&nbsp;Std&nbsp;1003.1-2001,
<a href="../functions/xsh_chap02_05.html#tag_02_05_02">Section 2.5.2, Stream Orientation and Encoding Rules</a>.</dd>
</dl>

<basefont size="3"> 

<h3><a name="tag_03_148"></a>Entire Regular Expression</h3>

<p>The concatenated set of one or more basic regular expressions or extended regular expressions that make up the pattern specified
for string selection. <basefont size="2"></p>

<dl>
<dt><b>Note:</b></dt>

<dd>Regular Expressions are defined in detail in <a href="xbd_chap09.html#tag_09"><i>Regular Expressions</i></a> .</dd>
</dl>

<basefont size="3"> 

<h3><a name="tag_03_149"></a>Epoch</h3>

<p>The time zero hours, zero minutes, zero seconds, on January 1, 1970 Coordinated Universal Time (UTC). <basefont size="2"></p>

<dl>
<dt><b>Note:</b></dt>

<dd>See also Seconds Since the Epoch defined in <a href="xbd_chap04.html#tag_04_14"><i>Seconds Since the Epoch</i></a> .</dd>
</dl>

<basefont size="3"> 

<h3><a name="tag_03_150"></a>Equivalence Class</h3>

<p>A set of collating elements with the same primary collation weight.</p>

<p>Elements in an equivalence class are typically elements that naturally group together, such as all accented letters based on the
same base letter.</p>

<p>The collation order of elements within an equivalence class is determined by the weights assigned on any subsequent levels after
the primary weight.</p>

<h3><a name="tag_03_151"></a>Era</h3>

<p>A locale-specific method for counting and displaying years. <basefont size="2"></p>

<dl>
<dt><b>Note:</b></dt>

<dd>The <i>LC_TIME</i> category is defined in detail in <a href="xbd_chap07.html#tag_07_03_05"><i>LC_TIME</i></a> .</dd>
</dl>

<basefont size="3"> 

<h3><a name="tag_03_152"></a>Event Management</h3>

<p>The mechanism that enables applications to register for and be made aware of external events such as data becoming available for
reading.</p>

<h3><a name="tag_03_153"></a>Executable File</h3>

<p>A regular file acceptable as a new process image file by the equivalent of the <i>exec</i> family of functions, and thus usable
as one form of a utility. The standard utilities described as compilers can produce executable files, but other unspecified methods
of producing executable files may also be provided. The internal format of an executable file is unspecified, but a conforming
application cannot assume an executable file is a text file.</p>

<h3><a name="tag_03_154"></a>Execute</h3>

<p>To perform command search and execution actions, as defined in the Shell and Utilities volume of IEEE&nbsp;Std&nbsp;1003.1-2001;
see also <a href="#tag_03_200">Invoke</a> . <basefont size="2"></p>

<dl>
<dt><b>Note:</b></dt>

<dd>Command Search and Execution is defined in detail in the Shell and Utilities volume of IEEE&nbsp;Std&nbsp;1003.1-2001, <a href=
"../utilities/xcu_chap02.html#tag_02_09_01_01">Section 2.9.1.1, Command Search and Execution</a>.</dd>
</dl>

<basefont size="3"> 

<h3><a name="tag_03_155"></a>Execution Time</h3>

<p>See <i>CPU Time</i> in <a href="#tag_03_117">CPU Time (Execution Time)</a> .</p>

<h3><a name="tag_03_156"></a>Execution Time Monitoring</h3>

<p>A set of execution time monitoring primitives that allow online measuring of thread and process execution times.</p>

<h3><a name="tag_03_157"></a>Expand</h3>

<p>In the shell command language, when not qualified, the act of applying word expansions. <basefont size="2"></p>

<dl>
<dt><b>Note:</b></dt>

<dd>Word Expansions are defined in detail in the Shell and Utilities volume of IEEE&nbsp;Std&nbsp;1003.1-2001, <a href=
"../utilities/xcu_chap02.html#tag_02_06">Section 2.6, Word Expansions</a>.</dd>
</dl>

<basefont size="3"> 

<h3><a name="tag_03_158"></a>Extended Regular Expression (ERE)</h3>

<p>A regular expression (see also <a href="#tag_03_316">Regular Expression</a> ) that is an alternative to the Basic Regular