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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2003 The Open Group, All Rights Reserved --><title>Utility Conventions</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2003 Edition<br>Copyright © 2001-2003 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h2><a name="tag_12"></a>Utility Conventions</h2><h3><a name="tag_12_01"></a>Utility Argument Syntax</h3><p>This section describes the argument syntax of the standard utilities and introduces terminology used throughoutIEEE Std 1003.1-2001 for describing the arguments processed by the utilities.</p><p>Within IEEE Std 1003.1-2001, a special notation is used for describing the syntax of a utility's arguments. Unlessotherwise noted, all utility descriptions use this notation, which is illustrated by this example (see the Shell and Utilitiesvolume of IEEE Std 1003.1-2001, <a href="../utilities/xcu_chap02.html#tag_02_09_01">Section 2.9.1, SimpleCommands</a>):</p><blockquote><pre><tt>utility_name</tt><b>[</b><tt>-a</tt><b>][</b><tt>-b</tt><b>][</b><tt>-c</tt> <i>option_argument</i><b>] [</b><tt>-d|-e</tt><b>][</b><tt>-f</tt><i>option_argument</i><b>][</b><i>operand</i><tt>...</tt><b>]</b></pre></blockquote><p>The notation used for the SYNOPSIS sections imposes requirements on the implementors of the standard utilities and provides asimple reference for the application developer or system user.</p><ol><li><p>The utility in the example is named <i>utility_name</i>. It is followed by options, option-arguments, and operands. Thearguments that consist of hyphens and single letters or digits, such as <tt>'a'</tt> , are known as "options" (or, historically,"flags"). Certain options are followed by an "option-argument", as shown with [ <b>-c</b> <i>option_argument</i>]. Thearguments following the last options and option-arguments are named "operands".</p></li><li><p>Option-arguments are sometimes shown separated from their options by <blank>s, sometimes directly adjacent. This reflectsthe situation that in some cases an option-argument is included within the same argument string as the option; in most cases it isthe next argument. The Utility Syntax Guidelines in <a href="#tag_12_02">Utility Syntax Guidelines</a> require that the option be aseparate argument from its option-argument, but there are some exceptions in IEEE Std 1003.1-2001 to ensure continuedoperation of historical applications:</p><ol type="a"><li><p>If the SYNOPSIS of a standard utility shows a <space> between an option and option-argument (as with [ <b>-c</b><i>option_argument</i>] in the example), a conforming application shall use separate arguments for that option and itsoption-argument.</p></li><li><p>If a <space> is not shown (as with [ <b>-f</b> <i>option_argument</i>] in the example), a conforming application shallplace an option and its option-argument directly adjacent in the same argument string, without intervening <blank>s.</p></li><li><p>Notwithstanding the preceding requirements on conforming applications, a conforming implementation shall permit an applicationto specify options and option-arguments as a single argument or as separate arguments whether or not a <space> is shown onthe synopsis line, <sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> except in those cases (marked with the XSI portability warning) where an option-argument isoptional and no separation can be used. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></p></li><li><p>A standard utility may also be implemented to operate correctly when the required separation into multiple arguments is violatedby a non-conforming application.</p></li></ol></li><li><p>Options are usually listed in alphabetical order unless this would make the utility description more confusing. There are noimplied relationships between the options based upon the order in which they appear, unless otherwise stated in the OPTIONSsection, or unless the exception in Guideline 11 of <a href="#tag_12_02">Utility Syntax Guidelines</a> applies. If an option thatdoes not have option-arguments is repeated, the results are undefined, unless otherwise stated.</p></li><li><p>Frequently, names of parameters that require substitution by actual values are shown with embedded underscores. Alternatively,parameters are shown as follows:</p><blockquote><pre><tt><</tt><i>parameter name</i><tt>></tt></pre></blockquote><p>The angle brackets are used for the symbolic grouping of a phrase representing a single parameter and conforming applicationsshall not include them in data submitted to the utility.</p></li><li><p>When a utility has only a few permissible options, they are sometimes shown individually, as in the example. Utilities with manyflags generally show all of the individual flags (that do not take option-arguments) grouped, as in:</p><blockquote><pre><tt>utility_name</tt> <b>[</b><tt>-abcDxyz</tt><b>][</b><tt>-p</tt> <i>arg</i><b>][</b><i>operand</i><b>]</b></pre></blockquote><p>Utilities with very complex arguments may be shown as follows:</p><blockquote><pre><tt>utility_name</tt> <b>[</b><tt>options</tt><b>][</b><i>operands</i><b>]</b></pre></blockquote></li><li><p>Unless otherwise specified, whenever an operand or option-argument is, or contains, a numeric value:</p><ul><li><p>The number is interpreted as a decimal integer.</p></li><li><p>Numerals in the range 0 to 2147483647 are syntactically recognized as numeric values.</p></li><li><p>When the utility description states that it accepts negative numbers as operands or option-arguments, numerals in the range-2147483647 to 2147483647 are syntactically recognized as numeric values.</p></li><li><p>Ranges greater than those listed here are allowed.</p></li></ul><p>This does not mean that all numbers within the allowable range are necessarily semantically correct. A standard utility thataccepts an option-argument or operand that is to be interpreted as a number, and for which a range of values smaller than thatshown above is permitted by the IEEE Std 1003.1-2001, describes that smaller range along with the description of theoption-argument or operand. If an error is generated, the utility's diagnostic message shall indicate that the value is out of thesupported range, not that it is syntactically incorrect.</p></li><li><p>Arguments or option-arguments enclosed in the <tt>'['</tt> and <tt>']'</tt> notation are optional and can be omitted. Conformingapplications shall not include the <tt>'['</tt> and <tt>']'</tt> symbols in data submitted to the utility.</p></li><li><p>Arguments separated by the <tt>'|'</tt> vertical bar notation are mutually-exclusive. Conforming applications shall not includethe <tt>'|'</tt> symbol in data submitted to the utility. Alternatively, mutually-exclusive options and operands may be listed withmultiple synopsis lines. For example:</p><blockquote><pre><tt>utility_name -d</tt><b>[</b><tt>-a</tt><b>][</b><tt>-c</tt> <i>option_argument</i><b>][</b><i>operand</i><tt>...</tt><b>]</b><tt>utility_name</tt><b>[</b><tt>-a</tt><b>][</b><tt>-b</tt><b>][</b><i>operand</i><tt>...</tt><b>]</b></pre></blockquote><p>When multiple synopsis lines are given for a utility, it is an indication that the utility has mutually-exclusive arguments.These mutually-exclusive arguments alter the functionality of the utility so that only certain other arguments are valid incombination with one of the mutually-exclusive arguments. Only one of the mutually-exclusive arguments is allowed for invocation ofthe utility. Unless otherwise stated in an accompanying OPTIONS section, the relationships between arguments depicted in theSYNOPSIS sections are mandatory requirements placed on conforming applications. The use of conflicting mutually-exclusive argumentsproduces undefined results, unless a utility description specifies otherwise. When an option is shown without the <tt>'['</tt> and<tt>']'</tt> brackets, it means that option is required for that version of the SYNOPSIS. However, it is not required to be thefirst argument, as shown in the example above, unless otherwise stated.</p></li><li><p>Ellipses ( <tt>"..."</tt> ) are used to denote that one or more occurrences of an option or operand are allowed. When an optionor an operand followed by ellipses is enclosed in brackets, zero or more options or operands can be specified. The forms:</p><blockquote><pre><tt>utility_name -f</tt> <i>option_argument</i><tt>...</tt><b>[</b><i>operand</i><tt>...</tt><b>]</b><tt>utility_name</tt> <b>[</b><tt>-g</tt> <i>option_argument</i><b>]</b><tt>...</tt><b>[</b><i>operand</i><tt>...</tt><b>]</b></pre></blockquote><p>indicate that multiple occurrences of the option and its option-argument preceding the ellipses are valid, with semantics asindicated in the OPTIONS section of the utility. (See also Guideline 11 in <a href="#tag_12_02">Utility Syntax Guidelines</a> .) Inthe first example, each option-argument requires a preceding <b>-f</b> and at least one <b>-f</b> <i>option_argument</i> must begiven.</p></li><li><p>When the synopsis line is too long to be printed on a single line in the Shell and Utilities volume ofIEEE Std 1003.1-2001, the indented lines following the initial line are continuation lines. An actual use of the commandwould appear on a single logical line.</p></li></ol><h3><a name="tag_12_02"></a>Utility Syntax Guidelines</h3><p>The following guidelines are established for the naming of utilities and for the specification of options, option-arguments, andoperands. The <a href="../functions/getopt.html"><i>getopt</i>()</a> function in the System Interfaces volume ofIEEE Std 1003.1-2001 assists utilities in handling options and operands that conform to these guidelines.</p><p>Operands and option-arguments can contain characters not specified in the portable character set.</p><p>The guidelines are intended to provide guidance to the authors of future utilities, such as those written specific to a localsystem or that are components of a larger application. Some of the standard utilities do not conform to all of these guidelines; inthose cases, the OPTIONS sections describe the deviations.</p><dl compact><dt><b>Guideline 1:</b></dt><dd>Utility names should be between two and nine characters, inclusive.</dd><dt><b>Guideline 2:</b></dt><dd>Utility names should include lowercase letters (the <b>lower</b> character classification) and digits only from the portablecharacter set.</dd><dt><b>Guideline 3:</b></dt><dd>Each option name should be a single alphanumeric character (the <b>alnum</b> character classification) from the portablecharacter set. The <b>-W</b> (capital-W) option shall be reserved for vendor options. <p>Multi-digit options should not be allowed.</p></dd><dt><b>Guideline 4:</b></dt><dd>All options should be preceded by the <tt>'-'</tt> delimiter character.</dd><dt><b>Guideline 5:</b></dt><dd>Options without option-arguments should be accepted when grouped behind one <tt>'-'</tt> delimiter.</dd><dt><b>Guideline 6:</b></dt><dd>Each option and option-argument should be a separate argument, except as noted in <a href="#tag_12_01">Utility ArgumentSyntax</a> , item (2).</dd><dt><b>Guideline 7:</b></dt><dd>Option-arguments should not be optional.</dd><dt><b>Guideline 8:</b></dt><dd>When multiple option-arguments are specified to follow a single option, they should be presented as a single argument, usingcommas within that argument or <blank>s within that argument to separate them.</dd><dt><b>Guideline 9:</b></dt><dd>All options should precede operands on the command line.</dd><dt><b>Guideline 10:</b></dt><dd>The argument <b>--</b> should be accepted as a delimiter indicating the end of options. Any following arguments should betreated as operands, even if they begin with the <tt>'-'</tt> character. The <b>--</b> argument should not be used as an option oras an operand.</dd><dt><b>Guideline 11:</b></dt><dd>The order of different options relative to one another should not matter, unless the options are documented asmutually-exclusive and such an option is documented to override any incompatible options preceding it. If an option that hasoption-arguments is repeated, the option and option-argument combinations should be interpreted in the order specified on thecommand line.</dd><dt><b>Guideline 12:</b></dt><dd>The order of operands may matter and position-related interpretations should be determined on a utility-specific basis.</dd><dt><b>Guideline 13:</b></dt><dd>For utilities that use operands to represent files to be opened for either reading or writing, the <tt>'-'</tt> operand shouldbe used only to mean standard input (or standard output when it is clear from context that an output file is being specified).</dd></dl><p>The utilities in the Shell and Utilities volume of IEEE Std 1003.1-2001 that claim conformance to these guidelinesshall conform completely to these guidelines as if these guidelines contained the term "shall" instead of "should". On someimplementations, the utilities accept usage in violation of these guidelines for backwards-compatibility as well as accepting therequired form.</p><p>It is recommended that all future utilities and applications use these guidelines to enhance user portability. The fact thatsome historical utilities could not be changed (to avoid breaking existing applications) should not deter this future goal.</p><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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