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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><meta name="viewport" content="width=device-width, initial-scale=0.8"/><title>15.7 Environment Variables</title><link rel="stylesheet" type="text/css" href="../scribble.css" title="default"/><link rel="stylesheet" type="text/css" href="extras.css" title="default"/><link rel="stylesheet" type="text/css" href="../racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-style.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../doc-site.css" title="default"/><script type="text/javascript" src="../scribble-common.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../doc-site.js"></script><script type="text/javascript" src="../local-redirect/local-redirect.js"></script><script type="text/javascript" src="../local-redirect/local-user-redirect.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--></head><body id="doc-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist tocviewlisttopspace"><div class="tocviewtitle"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_0");">►</a></td><td></td><td><a href="index.html" class="tocviewlink" data-pltdoc="x">The Racket Reference</a></td></tr></table></div><div class="tocviewsublisttop" style="display: none;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="model.html" class="tocviewlink" data-pltdoc="x">Language Model</a></td></tr><tr><td align="right">2 </td><td><a href="notation.html" class="tocviewlink" data-pltdoc="x">Notation for Documentation</a></td></tr><tr><td align="right">3 </td><td><a href="syntax.html" class="tocviewlink" data-pltdoc="x">Syntactic Forms</a></td></tr><tr><td align="right">4 </td><td><a href="data.html" class="tocviewlink" data-pltdoc="x">Datatypes</a></td></tr><tr><td align="right">5 </td><td><a href="structures.html" class="tocviewlink" data-pltdoc="x">Structures</a></td></tr><tr><td align="right">6 </td><td><a href="mzlib_class.html" class="tocviewlink" data-pltdoc="x">Classes and Objects</a></td></tr><tr><td align="right">7 </td><td><a href="mzlib_unit.html" class="tocviewlink" data-pltdoc="x">Units</a></td></tr><tr><td align="right">8 </td><td><a href="contracts.html" class="tocviewlink" data-pltdoc="x">Contracts</a></td></tr><tr><td align="right">9 </td><td><a href="match.html" class="tocviewlink" data-pltdoc="x">Pattern Matching</a></td></tr><tr><td align="right">10 </td><td><a href="control.html" class="tocviewlink" data-pltdoc="x">Control Flow</a></td></tr><tr><td align="right">11 </td><td><a href="concurrency.html" class="tocviewlink" data-pltdoc="x">Concurrency and Parallelism</a></td></tr><tr><td align="right">12 </td><td><a href="Macros.html" class="tocviewlink" data-pltdoc="x">Macros</a></td></tr><tr><td align="right">13 </td><td><a href="input-and-output.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr><tr><td align="right">14 </td><td><a href="security.html" class="tocviewlink" data-pltdoc="x">Reflection and Security</a></td></tr><tr><td align="right">15 </td><td><a href="os.html" class="tocviewselflink" data-pltdoc="x">Operating System</a></td></tr><tr><td align="right">16 </td><td><a href="memory.html" class="tocviewlink" data-pltdoc="x">Memory Management</a></td></tr><tr><td align="right">17 </td><td><a href="unsafe.html" class="tocviewlink" data-pltdoc="x">Unsafe Operations</a></td></tr><tr><td align="right">18 </td><td><a href="running.html" class="tocviewlink" data-pltdoc="x">Running Racket</a></td></tr><tr><td align="right"></td><td><a href="doc-bibliography.html" class="tocviewlink" data-pltdoc="x">Bibliography</a></td></tr><tr><td align="right"></td><td><a href="doc-index.html" class="tocviewlink" data-pltdoc="x">Index</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_1");">▼</a></td><td>15 </td><td><a href="os.html" class="tocviewlink" data-pltdoc="x">Operating System</a></td></tr></table><div class="tocviewsublistbottom" style="display: block;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">15.1 </td><td><a href="pathutils.html" class="tocviewlink" data-pltdoc="x">Paths</a></td></tr><tr><td align="right">15.2 </td><td><a href="Filesystem.html" class="tocviewlink" data-pltdoc="x">Filesystem</a></td></tr><tr><td align="right">15.3 </td><td><a href="networking.html" class="tocviewlink" data-pltdoc="x">Networking</a></td></tr><tr><td align="right">15.4 </td><td><a href="subprocess.html" class="tocviewlink" data-pltdoc="x">Processes</a></td></tr><tr><td align="right">15.5 </td><td><a href="logging.html" class="tocviewlink" data-pltdoc="x">Logging</a></td></tr><tr><td align="right">15.6 </td><td><a href="time.html" class="tocviewlink" data-pltdoc="x">Time</a></td></tr><tr><td align="right">15.7 </td><td><a href="envvars.html" class="tocviewselflink" data-pltdoc="x">Environment Variables</a></td></tr><tr><td align="right">15.8 </td><td><a href="runtime.html" class="tocviewlink" data-pltdoc="x">Environment and Runtime Information</a></td></tr><tr><td align="right">15.9 </td><td><a href="Command-Line_Parsing.html" class="tocviewlink" data-pltdoc="x">Command-<wbr></wbr>Line Parsing</a></td></tr><tr><td align="right">15.10 </td><td><a href="os-lib.html" class="tocviewlink" data-pltdoc="x">Additional Operating System Functions</a></td></tr></table></div></div></div><div class="tocsub"><div class="tocsubtitle">On this page:</div><table class="tocsublist" cellspacing="0"><tr><td><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">environment-<wbr></wbr>variables?</span></span></a></td></tr><tr><td><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._current-environment-variables%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">current-<wbr></wbr>environment-<wbr></wbr>variables</span></span></a></td></tr><tr><td><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._bytes-environment-variable-name~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">bytes-<wbr></wbr>environment-<wbr></wbr>variable-<wbr></wbr>name?</span></span></a></td></tr><tr><td><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._make-environment-variables%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">make-<wbr></wbr>environment-<wbr></wbr>variables</span></span></a></td></tr><tr><td><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables-ref%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">environment-<wbr></wbr>variables-<wbr></wbr>ref</span></span></a></td></tr><tr><td><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables-set%21%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">environment-<wbr></wbr>variables-<wbr></wbr>set!</span></span></a></td></tr><tr><td><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables-names%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">environment-<wbr></wbr>variables-<wbr></wbr>names</span></span></a></td></tr><tr><td><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables-copy%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">environment-<wbr></wbr>variables-<wbr></wbr>copy</span></span></a></td></tr><tr><td><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._getenv%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">getenv</span></span></a></td></tr><tr><td><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._putenv%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">putenv</span></span></a></td></tr><tr><td><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._string-environment-variable-name~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">string-<wbr></wbr>environment-<wbr></wbr>variable-<wbr></wbr>name?</span></span></a></td></tr></table></div></div><div class="maincolumn"><div class="main"><div class="navsettop"><span class="navleft"><form class="searchform"><input class="searchbox" id="searchbox" type="text" tabindex="1" placeholder="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "8.6", "../");"/></form> <a href="https://docs.racket-lang.org/index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("8.6");">top</a><span class="tocsettoggle"> <a href="javascript:void(0);" title="show/hide table of contents" onclick="TocsetToggle();">contents</a></span></span><span class="navright"> <a href="time.html" title="backward to "15.6 Time"" data-pltdoc="x">← prev</a> <a href="os.html" title="up to "15 Operating System"" data-pltdoc="x">up</a> <a href="runtime.html" title="forward to "15.8 Environment and Runtime Information"" data-pltdoc="x">next →</a></span> </div><h4 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""envvars"">15.7<tt> </tt><a name="(part._envvars)"></a>Environment Variables</h4><p>An <a name="(tech._environment._variable._set)"></a><span style="font-style: italic">environment variable set</span> encapsulates a partial mapping
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from byte strings to byte strings. A Racket process’s initial
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<a href="envvars.html#%28tech._environment._variable._set%29" class="techoutside" data-pltdoc="x"><span class="techinside">environment variable set</span></a> is connected to the operating system’s
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environment variables: accesses or changes to the set read or change
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operating-system environment variables for the Racket process.</p><p>Since Windows environment variables are case-insensitive,
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<a href="envvars.html#%28tech._environment._variable._set%29" class="techoutside" data-pltdoc="x"><span class="techinside">environment variable set</span></a>’s key byte strings on Windows are
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case-folded. More precisely, key byte strings are coerced to a UTF-8
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encoding of characters that are converted to lowercase via
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<span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string-locale-downcase%29%29" class="RktValLink" data-pltdoc="x">string-locale-downcase</a></span>.</p><p>The current <a href="envvars.html#%28tech._environment._variable._set%29" class="techoutside" data-pltdoc="x"><span class="techinside">environment variable set</span></a>, which is determined by
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the <span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._current-environment-variables%29%29" class="RktValLink" data-pltdoc="x">current-environment-variables</a></span> parameter, is propagated to
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a <a href="subprocess.html#%28tech._subproces%29" class="techoutside" data-pltdoc="x"><span class="techinside">subprocess</span></a> when the <a href="subprocess.html#%28tech._subproces%29" class="techoutside" data-pltdoc="x"><span class="techinside">subprocess</span></a> is created.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._environment-variables~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">environment-variables?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">v</span> is an <a href="envvars.html#%28tech._environment._variable._set%29" class="techoutside" data-pltdoc="x"><span class="techinside">environment variable
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set</span></a>, <span class="RktVal">#f</span> otherwise.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._current-environment-variables))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._current-environment-variables%29%29" class="RktValDef RktValLink" data-pltdoc="x">current-environment-variables</a></span></span><span class="RktPn"></span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables~3f%29%29" class="RktValLink" data-pltdoc="x">environment-variables?</a></span></p></blockquote></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._current-environment-variables%29%29" class="RktValDef RktValLink" data-pltdoc="x">current-environment-variables</a></span></span><span class="hspace"> </span><span class="RktVar">env</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">env</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables~3f%29%29" class="RktValLink" data-pltdoc="x">environment-variables?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">A <a href="eval-model.html#%28tech._parameter%29" class="techoutside" data-pltdoc="x"><span class="techinside">parameter</span></a> that determines the <a href="envvars.html#%28tech._environment._variable._set%29" class="techoutside" data-pltdoc="x"><span class="techinside">environment variable set</span></a>
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that is propagated to a <a href="subprocess.html#%28tech._subproces%29" class="techoutside" data-pltdoc="x"><span class="techinside">subprocess</span></a> and that is used as the
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default set for <span class="RktSym"><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._getenv%29%29" class="RktValLink" data-pltdoc="x">getenv</a></span> and <span class="RktSym"><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._putenv%29%29" class="RktValLink" data-pltdoc="x">putenv</a></span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/misc..rkt)._bytes-environment-variable-name~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._bytes-environment-variable-name~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">bytes-environment-variable-name?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">v</span> is a byte string and if it is valid
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for an environment variable name. An environment variable name must
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contain no bytes with the value <span class="RktVal">0</span> or <span class="RktVal">61</span>, where
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<span class="RktVal">61</span> is <span class="RktPn">(</span><span class="RktSym"><a href="characters.html#%28def._%28%28quote._~23~25kernel%29._char-~3einteger%29%29" class="RktValLink" data-pltdoc="x">char->integer</a></span><span class="stt"> </span><span class="RktVal">#\=</span><span class="RktPn">)</span>. On Windows, an
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environment variable name also must have a non-zero length.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._make-environment-variables))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._make-environment-variables%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-environment-variables</a></span></span><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span><span class="RktVar">val</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables~3f%29%29" class="RktValLink" data-pltdoc="x">environment-variables?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._bytes-environment-variable-name~3f%29%29" class="RktValLink" data-pltdoc="x">bytes-environment-variable-name?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">val</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="subprocess.html#%28def._%28%28lib._racket%2Fsystem..rkt%29._bytes-no-nuls~3f%29%29" class="RktValLink" data-pltdoc="x">bytes-no-nuls?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Creates a fresh <a href="envvars.html#%28tech._environment._variable._set%29" class="techoutside" data-pltdoc="x"><span class="techinside">environment variable set</span></a> that is initialized
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with the given <span class="RktVar">name</span> to <span class="RktVar">val</span> mappings.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._environment-variables-ref))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables-ref%29%29" class="RktValDef RktValLink" data-pltdoc="x">environment-variables-ref</a></span></span><span class="hspace"> </span><span class="RktVar">env</span><span class="hspace"> </span><span class="RktVar">name</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="subprocess.html#%28def._%28%28lib._racket%2Fsystem..rkt%29._bytes-no-nuls~3f%29%29" class="RktValLink" data-pltdoc="x">bytes-no-nuls?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">env</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables~3f%29%29" class="RktValLink" data-pltdoc="x">environment-variables?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._bytes-environment-variable-name~3f%29%29" class="RktValLink" data-pltdoc="x">bytes-environment-variable-name?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns the mapping for <span class="RktVar">name</span> in <span class="RktVar">env</span>, returning
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<span class="RktVal">#f</span> if <span class="RktVar">name</span> has no mapping.</div></p><p>Normally, <span class="RktVar">name</span> should be a byte-string encoding of a string
|
|
using the default encoding of the current <a href="encodings.html#%28tech._locale%29" class="techoutside" data-pltdoc="x"><span class="techinside">locale</span></a>. On Windows,
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|
<span class="RktVar">name</span> is coerced to a UTF-8 encoding and case-normalized.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._environment-variables-set!))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables-set%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">environment-variables-set!</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">env</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">name</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">maybe-bstr</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span><span class="RktOpt">[</span></td><td valign="top"><span class="RktVar">fail</span><span class="RktOpt">]</span><span class="RktPn">)</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">→</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">env</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables~3f%29%29" class="RktValLink" data-pltdoc="x">environment-variables?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._bytes-environment-variable-name~3f%29%29" class="RktValLink" data-pltdoc="x">bytes-environment-variable-name?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">maybe-bstr</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="subprocess.html#%28def._%28%28lib._racket%2Fsystem..rkt%29._bytes-no-nuls~3f%29%29" class="RktValLink" data-pltdoc="x">bytes-no-nuls?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="argcontract"><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">fail</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">:</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span><span class="RktPn">)</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">=</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise%29%29" class="RktValLink" data-pltdoc="x">raise</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail</a></span><span class="hspace"> </span><span class="RktSym">....</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Changes the mapping for <span class="RktVar">name</span> in <span class="RktVar">env</span> to
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<span class="RktVar">maybe-bstr</span>. If <span class="RktVar">maybe-bstr</span> is <span class="RktVal">#f</span> and
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<span class="RktVar">env</span> is the initial <a href="envvars.html#%28tech._environment._variable._set%29" class="techoutside" data-pltdoc="x"><span class="techinside">environment variable set</span></a> of the
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Racket process, then the operating system environment-variable mapping
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|
for <span class="RktVar">name</span> is removed.</div></p><p>Normally, <span class="RktVar">name</span> and <span class="RktVar">maybe-bstr</span> should be a
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|
byte-string encoding of a string using the default encoding of the
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current <a href="encodings.html#%28tech._locale%29" class="techoutside" data-pltdoc="x"><span class="techinside">locale</span></a>. On Windows, <span class="RktVar">name</span> is
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coerced to a UTF-8 encoding and case-normalized, and
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<span class="RktVar">maybe-bstr</span> is coerced to a UTF-8 encoding if <span class="RktVar">env</span> is
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the initial <a href="envvars.html#%28tech._environment._variable._set%29" class="techoutside" data-pltdoc="x"><span class="techinside">environment variable set</span></a> of the Racket process.</p><p>On success, the result of <span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables-set%21%29%29" class="RktValLink" data-pltdoc="x">environment-variables-set!</a></span> is
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<a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=guide&rel=void_undefined.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="nobreak"><span class="RktRes">#<void></span></span></a>. If <span class="RktVar">env</span> is the initial <a href="envvars.html#%28tech._environment._variable._set%29" class="techoutside" data-pltdoc="x"><span class="techinside">environment
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variable set</span></a> of the Racket process, then attempting to adjust the
|
|
operating system environment-variable mapping might fail for some reason,
|
|
in which case <span class="RktVar">fail</span> is called in tail position with respect to the
|
|
<span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables-set%21%29%29" class="RktValLink" data-pltdoc="x">environment-variables-set!</a></span>. The default <span class="RktVar">fail</span> raises
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an exception.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._environment-variables-names))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables-names%29%29" class="RktValDef RktValLink" data-pltdoc="x">environment-variables-names</a></span></span><span class="hspace"> </span><span class="RktVar">env</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._bytes-environment-variable-name~3f%29%29" class="RktValLink" data-pltdoc="x">bytes-environment-variable-name?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">env</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables~3f%29%29" class="RktValLink" data-pltdoc="x">environment-variables?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a list of byte strings that corresponds to names mapped by
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<span class="RktVar">env</span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._environment-variables-copy))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables-copy%29%29" class="RktValDef RktValLink" data-pltdoc="x">environment-variables-copy</a></span></span><span class="hspace"> </span><span class="RktVar">env</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables~3f%29%29" class="RktValLink" data-pltdoc="x">environment-variables?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">env</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables~3f%29%29" class="RktValLink" data-pltdoc="x">environment-variables?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns an <a href="envvars.html#%28tech._environment._variable._set%29" class="techoutside" data-pltdoc="x"><span class="techinside">environment variable set</span></a> that is initialized with
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the same mappings as <span class="RktVar">env</span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/misc..rkt)._getenv))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._getenv%29%29" class="RktValDef RktValLink" data-pltdoc="x">getenv</a></span></span><span class="hspace"> </span><span class="RktVar">name</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="subprocess.html#%28def._%28%28lib._racket%2Fsystem..rkt%29._string-no-nuls~3f%29%29" class="RktValLink" data-pltdoc="x">string-no-nuls?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._string-environment-variable-name~3f%29%29" class="RktValLink" data-pltdoc="x">string-environment-variable-name?</a></span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/misc..rkt)._putenv))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._putenv%29%29" class="RktValDef RktValLink" data-pltdoc="x">putenv</a></span></span><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span><span class="RktVar">value</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._string-environment-variable-name~3f%29%29" class="RktValLink" data-pltdoc="x">string-environment-variable-name?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">value</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="subprocess.html#%28def._%28%28lib._racket%2Fsystem..rkt%29._string-no-nuls~3f%29%29" class="RktValLink" data-pltdoc="x">string-no-nuls?</a></span></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Convenience wrappers for <span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables-ref%29%29" class="RktValLink" data-pltdoc="x">environment-variables-ref</a></span> and
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<span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._environment-variables-set%21%29%29" class="RktValLink" data-pltdoc="x">environment-variables-set!</a></span> that convert between strings and
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byte strings using the current <a href="encodings.html#%28tech._locale%29" class="techoutside" data-pltdoc="x"><span class="techinside">locale</span></a>’s default encoding (using
|
|
<span class="RktVal">#\?</span> as the replacement character for encoding errors) and
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|
always using the current <a href="envvars.html#%28tech._environment._variable._set%29" class="techoutside" data-pltdoc="x"><span class="techinside">environment variable set</span></a> from
|
|
<span class="RktSym"><a href="envvars.html#%28def._%28%28quote._~23~25kernel%29._current-environment-variables%29%29" class="RktValLink" data-pltdoc="x">current-environment-variables</a></span>. The <span class="RktSym"><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._putenv%29%29" class="RktValLink" data-pltdoc="x">putenv</a></span> function
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|
returns <span class="RktVal">#t</span> for success and <span class="RktVal">#f</span> for failure.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/misc..rkt)._string-environment-variable-name~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._string-environment-variable-name~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">string-environment-variable-name?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">v</span> is a string and if its encoding
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|
using the current <a href="encodings.html#%28tech._locale%29" class="techoutside" data-pltdoc="x"><span class="techinside">locale</span></a>’s encoding is valid for an environment
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variable name according to <span class="RktSym"><a href="envvars.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._bytes-environment-variable-name~3f%29%29" class="RktValLink" data-pltdoc="x">bytes-environment-variable-name?</a></span>.</div></p><div class="navsetbottom"><span class="navleft"><form class="searchform"><input class="searchbox" id="searchbox" type="text" tabindex="1" placeholder="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "8.6", "../");"/></form> <a href="https://docs.racket-lang.org/index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("8.6");">top</a><span class="tocsettoggle"> <a href="javascript:void(0);" title="show/hide table of contents" onclick="TocsetToggle();">contents</a></span></span><span class="navright"> <a href="time.html" title="backward to "15.6 Time"" data-pltdoc="x">← prev</a> <a href="os.html" title="up to "15 Operating System"" data-pltdoc="x">up</a> <a href="runtime.html" title="forward to "15.8 Environment and Runtime Information"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html> |