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<h1 class="chapter">Definitions</h1> <p>These definitions are used throughout the remainder of this manual. </p> <dl compact> <dt id="index-POSIX"><span><code>POSIX</code></span></dt> <dd>
<p>A family of open system standards based on Unix. Bash is primarily concerned with the Shell and Utilities portion of the <small>POSIX</small> 1003.1 standard. </p> </dd> <dt><span><code>blank</code></span></dt> <dd>
<p>A space or tab character. </p> </dd> <dt id="index-builtin-1"><span><code>builtin</code></span></dt> <dd>
<p>A command that is implemented internally by the shell itself, rather than by an executable program somewhere in the file system. </p> </dd> <dt id="index-control-operator"><span><code>control operator</code></span></dt> <dd>
<p>A <code>token</code> that performs a control function. It is a <code>newline</code> or one of the following: ‘<samp>||</samp>’, ‘<samp>&&</samp>’, ‘<samp>&</samp>’, ‘<samp>;</samp>’, ‘<samp>;;</samp>’, ‘<samp>;&</samp>’, ‘<samp>;;&</samp>’, ‘<samp>|</samp>’, ‘<samp>|&</samp>’, ‘<samp>(</samp>’, or ‘<samp>)</samp>’. </p> </dd> <dt id="index-exit-status"><span><code>exit status</code></span></dt> <dd>
<p>The value returned by a command to its caller. The value is restricted to eight bits, so the maximum value is 255. </p> </dd> <dt id="index-field"><span><code>field</code></span></dt> <dd>
<p>A unit of text that is the result of one of the shell expansions. After expansion, when executing a command, the resulting fields are used as the command name and arguments. </p> </dd> <dt id="index-filename"><span><code>filename</code></span></dt> <dd>
<p>A string of characters used to identify a file. </p> </dd> <dt id="index-job"><span><code>job</code></span></dt> <dd>
<p>A set of processes comprising a pipeline, and any processes descended from it, that are all in the same process group. </p> </dd> <dt id="index-job-control"><span><code>job control</code></span></dt> <dd>
<p>A mechanism by which users can selectively stop (suspend) and restart (resume) execution of processes. </p> </dd> <dt id="index-metacharacter"><span><code>metacharacter</code></span></dt> <dd>
<p>A character that, when unquoted, separates words. A metacharacter is a <code>space</code>, <code>tab</code>, <code>newline</code>, or one of the following characters: ‘<samp>|</samp>’, ‘<samp>&</samp>’, ‘<samp>;</samp>’, ‘<samp>(</samp>’, ‘<samp>)</samp>’, ‘<samp><</samp>’, or ‘<samp>></samp>’. </p> </dd> <dt id="index-name"><span><code>name</code></span></dt> <dd>
<p>A <code>word</code> consisting solely of letters, numbers, and underscores, and beginning with a letter or underscore. <code>Name</code>s are used as shell variable and function names. Also referred to as an <code>identifier</code>. </p> </dd> <dt id="index-operator_002c-shell"><span><code>operator</code></span></dt> <dd>
<p>A <code>control operator</code> or a <code>redirection operator</code>. See <a href="redirections">Redirections</a>, for a list of redirection operators. Operators contain at least one unquoted <code>metacharacter</code>. </p> </dd> <dt id="index-process-group"><span><code>process group</code></span></dt> <dd>
<p>A collection of related processes each having the same process group <small>ID</small>. </p> </dd> <dt id="index-process-group-ID"><span><code>process group ID</code></span></dt> <dd>
<p>A unique identifier that represents a <code>process group</code> during its lifetime. </p> </dd> <dt id="index-reserved-word"><span><code>reserved word</code></span></dt> <dd>
<p>A <code>word</code> that has a special meaning to the shell. Most reserved words introduce shell flow control constructs, such as <code>for</code> and <code>while</code>. </p> </dd> <dt id="index-return-status"><span><code>return status</code></span></dt> <dd>
<p>A synonym for <code>exit status</code>. </p> </dd> <dt id="index-signal"><span><code>signal</code></span></dt> <dd>
<p>A mechanism by which a process may be notified by the kernel of an event occurring in the system. </p> </dd> <dt id="index-special-builtin"><span><code>special builtin</code></span></dt> <dd>
<p>A shell builtin command that has been classified as special by the <small>POSIX</small> standard. </p> </dd> <dt id="index-token"><span><code>token</code></span></dt> <dd>
<p>A sequence of characters considered a single unit by the shell. It is either a <code>word</code> or an <code>operator</code>. </p> </dd> <dt id="index-word"><span><code>word</code></span></dt> <dd><p>A sequence of characters treated as a unit by the shell. Words may not include unquoted <code>metacharacters</code>. </p></dd> </dl><div class="_attribution">
<p class="_attribution-p">
Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.<br>Licensed under the GNU Free Documentation License.<br>
<a href="https://www.gnu.org/software/bash/manual/html_node/Definitions.html" class="_attribution-link">https://www.gnu.org/software/bash/manual/html_node/Definitions.html</a>
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