mirror of
https://github.com/rawiriblundell/wiki.bash-hackers.org
synced 2024-11-02 00:53:07 +01:00
468 lines
30 KiB
Plaintext
468 lines
30 KiB
Plaintext
<!DOCTYPE html>
|
|
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" dir="ltr" class="no-js">
|
|
<head><script type="text/javascript" src="/_static/js/bundle-playback.js?v=TPXmWR5s" charset="utf-8"></script>
|
|
<script type="text/javascript" src="/_static/js/wombat.js?v=txqj7nKC" charset="utf-8"></script>
|
|
<script type="text/javascript">
|
|
__wm.init("http://web.archive.org/web");
|
|
__wm.wombat("https://wiki.bash-hackers.org/syntax/redirection?do=edit","20230315170826","http://web.archive.org/","web","/_static/",
|
|
"1678900106");
|
|
</script>
|
|
<link rel="stylesheet" type="text/css" href="/_static/css/banner-styles.css?v=S1zqJCYt" />
|
|
<link rel="stylesheet" type="text/css" href="/_static/css/iconochive.css?v=qtvMKcIJ" />
|
|
<!-- End Wayback Rewrite JS Include -->
|
|
|
|
<meta charset="UTF-8"/>
|
|
<title>Redirection [Bash Hackers Wiki]</title>
|
|
<script>(function(H){H.className=H.className.replace(/\bno-js\b/,'js')})(document.documentElement)</script>
|
|
<meta name="viewport" content="width=device-width,initial-scale=1"/>
|
|
<link rel="shortcut icon" href="/web/20230315170826im_/https://wiki.bash-hackers.org/lib/tpl/bootstrap3/images/favicon.ico"/>
|
|
<link rel="apple-touch-icon" href="/web/20230315170826im_/https://wiki.bash-hackers.org/lib/tpl/bootstrap3/images/apple-touch-icon.png"/>
|
|
<meta name="generator" content="DokuWiki"/>
|
|
<meta name="robots" content="noindex,nofollow"/>
|
|
<link type="text/css" rel="stylesheet" href="/web/20230315170826cs_/https://wiki.bash-hackers.org/lib/tpl/bootstrap3/assets/bootstrap/default/bootstrap.min.css"/>
|
|
<link rel="search" type="application/opensearchdescription+xml" href="/web/20230315170826/https://wiki.bash-hackers.org/lib/exe/opensearch.php" title="Bash Hackers Wiki"/>
|
|
<link rel="start" href="/"/>
|
|
<link rel="contents" href="/syntax/redirection?do=index" title="Sitemap"/>
|
|
<link rel="manifest" href="/web/20230315170826/https://wiki.bash-hackers.org/lib/exe/manifest.php"/>
|
|
<link rel="alternate" type="application/rss+xml" title="Recent Changes" href="/web/20230315170826/https://wiki.bash-hackers.org/feed.php"/>
|
|
<link rel="alternate" type="application/rss+xml" title="Current namespace" href="/web/20230315170826/https://wiki.bash-hackers.org/feed.php?mode=list&ns=syntax"/>
|
|
<link rel="alternate" type="text/html" title="Plain HTML" href="/web/20230315170826/https://wiki.bash-hackers.org/_export/xhtml/syntax/redirection"/>
|
|
<link rel="alternate" type="text/plain" title="Wiki Markup" href="/web/20230315170826/https://wiki.bash-hackers.org/_export/raw/syntax/redirection"/>
|
|
<link rel="stylesheet" type="text/css" href="/web/20230315170826cs_/https://wiki.bash-hackers.org/lib/exe/css.php?t=bootstrap3&tseed=54923c3deda180f2db5bd755cd8fbf1a"/>
|
|
<!--[if gte IE 9]><!-->
|
|
<script type="text/javascript">/*<![CDATA[*/var NS='syntax';var JSINFO = {"updatable":1,"userreplace":1,"default_macro_string":"","plugins":{"edittable":{"default columnwidth":""}},"move_renameokay":false,"isadmin":0,"isauth":0,"bootstrap3":{"mode":"source","toc":[],"config":{"collapsibleSections":0,"fixedTopNavbar":1,"showSemanticPopup":0,"sidebarOnNavbar":0,"tagsOnTop":1,"tocAffix":1,"tocCollapseOnScroll":1,"tocCollapsed":0,"tocLayout":"default","useAnchorJS":1,"useAlternativeToolbarIcons":1}},"id":"syntax:redirection","namespace":"syntax","ACT":"source","useHeadingNavigation":1,"useHeadingContent":1};
|
|
/*!]]>*/</script>
|
|
<script type="text/javascript" charset="utf-8" src="/web/20230315170826js_/https://wiki.bash-hackers.org/lib/exe/jquery.php?tseed=23f888679b4f1dc26eef34902aca964f"></script>
|
|
<script type="text/javascript" charset="utf-8" src="/web/20230315170826js_/https://wiki.bash-hackers.org/lib/exe/js.php?t=bootstrap3&tseed=54923c3deda180f2db5bd755cd8fbf1a"></script>
|
|
<script type="text/javascript">/*<![CDATA[*/if (typeof IconifyConfig == 'undefined') { var IconifyConfig = { 'defaultAPI' : '/lib/tpl/bootstrap3/iconify.php?prefix={prefix}&icons={icons}' } }
|
|
/*!]]>*/</script>
|
|
<script type="text/javascript" src="/web/20230315170826js_/https://wiki.bash-hackers.org/lib/tpl/bootstrap3/assets/bootstrap/js/bootstrap.min.js"></script>
|
|
<script type="text/javascript" src="/web/20230315170826js_/https://wiki.bash-hackers.org/lib/tpl/bootstrap3/assets/anchorjs/anchor.min.js"></script>
|
|
<script type="text/javascript" src="/web/20230315170826js_/https://wiki.bash-hackers.org/lib/tpl/bootstrap3/assets/typeahead/bootstrap3-typeahead.min.js"></script>
|
|
<script type="text/javascript" src="/web/20230315170826js_/https://wiki.bash-hackers.org/lib/tpl/bootstrap3/assets/iconify/iconify.min.js"></script>
|
|
<script type="text/javascript" src="/web/20230315170826js_/https://wiki.bash-hackers.org/lib/tpl/bootstrap3/assets/iconify/plugins/fa.js"></script>
|
|
<!--<![endif]-->
|
|
<style type="text/css">@media screen { body { margin-top: 65px; } #dw__toc.affix { top: 55px; position: fixed !important; } #dw__toc .nav .nav .nav { display: none; } }</style>
|
|
<!--[if lt IE 9]>
|
|
<script type="text/javascript" src="https://oss.maxcdn.com/html5shiv/3.7.2/html5shiv.min.js"></script>
|
|
<script type="text/javascript" src="https://oss.maxcdn.com/respond/1.4.2/respond.min.js"></script>
|
|
<![endif]-->
|
|
</head>
|
|
<body class="default dokuwiki mode_source tpl_bootstrap3 dw-page-on-panel dw-fluid-container" data-page-id="syntax:redirection"><div class="dokuwiki">
|
|
<header id="dokuwiki__header" class="dw-container dokuwiki container-fluid mx-5">
|
|
<!-- navbar -->
|
|
<nav id="dw__navbar" class="navbar navbar-fixed-top navbar-default" role="navigation">
|
|
|
|
<div class="dw-container container-fluid mx-5">
|
|
|
|
<div class="navbar-header">
|
|
|
|
<button class="navbar-toggle" type="button" data-toggle="collapse" data-target=".navbar-collapse">
|
|
<span class="icon-bar"></span>
|
|
<span class="icon-bar"></span>
|
|
<span class="icon-bar"></span>
|
|
</button>
|
|
|
|
<a class="navbar-brand d-flex align-items-center" href="/web/20230315170826/https://wiki.bash-hackers.org/start" accesskey="h" title="Bash Hackers Wiki"><img id="dw__logo" class="pull-left h-100 mr-4" alt="Bash Hackers Wiki" src="/web/20230315170826im_/https://wiki.bash-hackers.org/lib/tpl/bootstrap3/images/logo.png"/><div class="pull-right"><div id="dw__title">Bash Hackers Wiki</div></div></a>
|
|
</div>
|
|
|
|
<div class="collapse navbar-collapse">
|
|
|
|
|
|
|
|
|
|
<div class="navbar-right" id="dw__navbar_items">
|
|
|
|
|
|
<!-- navbar-searchform -->
|
|
<form action="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection" accept-charset="utf-8" class="navbar-form navbar-left search" id="dw__search" method="get" role="search">
|
|
<div class="input-group">
|
|
<input id="qsearch" autocomplete="off" type="search" placeholder="Search" value="" accesskey="f" name="q" class="form-control" title="[F]"/>
|
|
<div class="input-group-btn">
|
|
<button class="btn btn-default" type="submit" title="Search">
|
|
<span class="iconify" data-icon="mdi:magnify"></span> </button>
|
|
</div>
|
|
|
|
</div>
|
|
<input type="hidden" name="do" value="search"/>
|
|
</form>
|
|
<!-- /navbar-searchform -->
|
|
<!-- tools-menu -->
|
|
<ul class="nav navbar-nav dw-action-icon" id="dw__tools">
|
|
|
|
|
|
<li class="dropdown">
|
|
|
|
<a href="" class="dropdown-toggle" data-target="#" data-toggle="dropdown" title="" role="button" aria-haspopup="true" aria-expanded="false">
|
|
<span class="iconify" data-icon="mdi:wrench"></span> <span class="hidden-lg hidden-md hidden-sm">Tools</span> <span class="caret"></span>
|
|
</a>
|
|
|
|
<ul class="dropdown-menu tools" role="menu">
|
|
|
|
<li class="dropdown-header">
|
|
<span class="iconify" data-icon="mdi:account"></span> User Tools </li>
|
|
|
|
<li class="action"><a href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection?do=register" title="Register" rel="nofollow" class="menuitem register"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M15 14c-2.67 0-8 1.33-8 4v2h16v-2c0-2.67-5.33-4-8-4m-9-4V7H4v3H1v2h3v3h2v-3h3v-2m6 2a4 4 0 0 0 4-4 4 4 0 0 0-4-4 4 4 0 0 0-4 4 4 4 0 0 0 4 4z"/></svg><span>Register</span></a></li><li class="action"><a href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection?do=login&sectok=" title="Log In" rel="nofollow" class="menuitem login"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M10 17.25V14H3v-4h7V6.75L15.25 12 10 17.25M8 2h9a2 2 0 0 1 2 2v16a2 2 0 0 1-2 2H8a2 2 0 0 1-2-2v-4h2v4h9V4H8v4H6V4a2 2 0 0 1 2-2z"/></svg><span>Log In</span></a></li>
|
|
<li class="divider" role="separator"></li>
|
|
|
|
|
|
<li class="dropdown-header">
|
|
<span class="iconify" data-icon="mdi:toolbox"></span> Site Tools </li>
|
|
|
|
<li class="action"><a href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection?do=recent" title="Recent Changes [r]" rel="nofollow" accesskey="r" class="menuitem recent"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M15 13h1.5v2.82l2.44 1.41-.75 1.3L15 16.69V13m4-5H5v11h4.67c-.43-.91-.67-1.93-.67-3a7 7 0 0 1 7-7c1.07 0 2.09.24 3 .67V8M5 21a2 2 0 0 1-2-2V5c0-1.11.89-2 2-2h1V1h2v2h8V1h2v2h1a2 2 0 0 1 2 2v6.1c1.24 1.26 2 2.99 2 4.9a7 7 0 0 1-7 7c-1.91 0-3.64-.76-4.9-2H5m11-9.85A4.85 4.85 0 0 0 11.15 16c0 2.68 2.17 4.85 4.85 4.85A4.85 4.85 0 0 0 20.85 16c0-2.68-2.17-4.85-4.85-4.85z"/></svg><span>Recent Changes</span></a></li><li class="action"><a href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection?do=media&ns=syntax" title="Media Manager" rel="nofollow" class="menuitem media"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M7 15l4.5-6 3.5 4.5 2.5-3L21 15m1-11h-8l-2-2H6a2 2 0 0 0-2 2v12a2 2 0 0 0 2 2h16a2 2 0 0 0 2-2V6a2 2 0 0 0-2-2M2 6H0v14a2 2 0 0 0 2 2h18v-2H2V6z"/></svg><span>Media Manager</span></a></li><li class="action"><a href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection?do=index" title="Sitemap [x]" rel="nofollow" accesskey="x" class="menuitem index"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M3 3h6v4H3V3m12 7h6v4h-6v-4m0 7h6v4h-6v-4m-2-4H7v5h6v2H5V9h2v2h6v2z"/></svg><span>Sitemap</span></a></li>
|
|
<li class="divider" role="separator"></li>
|
|
|
|
|
|
<li class="dropdown-header">
|
|
<span class="iconify" data-icon="mdi:file-document-outline"></span> Page Tools </li>
|
|
|
|
<li class="action"><a href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection?do=" title="Show page [v]" rel="nofollow" accesskey="v" class="menuitem show"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M13 9h5.5L13 3.5V9M6 2h8l6 6v12a2 2 0 0 1-2 2H6a2 2 0 0 1-2-2V4c0-1.11.89-2 2-2m9 16v-2H6v2h9m3-4v-2H6v2h12z"/></svg><span>Show page</span></a></li><li class="action"><a href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection?do=revisions" title="Old revisions [o]" rel="nofollow" accesskey="o" class="menuitem revs"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M11 7v5.11l4.71 2.79.79-1.28-4-2.37V7m0-5C8.97 2 5.91 3.92 4.27 6.77L2 4.5V11h6.5L5.75 8.25C6.96 5.73 9.5 4 12.5 4a7.5 7.5 0 0 1 7.5 7.5 7.5 7.5 0 0 1-7.5 7.5c-3.27 0-6.03-2.09-7.06-5h-2.1c1.1 4.03 4.77 7 9.16 7 5.24 0 9.5-4.25 9.5-9.5A9.5 9.5 0 0 0 12.5 2z"/></svg><span>Old revisions</span></a></li><li class="action"><a href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection?do=backlink" title="Backlinks" rel="nofollow" class="menuitem backlink"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M10.59 13.41c.41.39.41 1.03 0 1.42-.39.39-1.03.39-1.42 0a5.003 5.003 0 0 1 0-7.07l3.54-3.54a5.003 5.003 0 0 1 7.07 0 5.003 5.003 0 0 1 0 7.07l-1.49 1.49c.01-.82-.12-1.64-.4-2.42l.47-.48a2.982 2.982 0 0 0 0-4.24 2.982 2.982 0 0 0-4.24 0l-3.53 3.53a2.982 2.982 0 0 0 0 4.24m2.82-4.24c.39-.39 1.03-.39 1.42 0a5.003 5.003 0 0 1 0 7.07l-3.54 3.54a5.003 5.003 0 0 1-7.07 0 5.003 5.003 0 0 1 0-7.07l1.49-1.49c-.01.82.12 1.64.4 2.43l-.47.47a2.982 2.982 0 0 0 0 4.24 2.982 2.982 0 0 0 4.24 0l3.53-3.53a2.982 2.982 0 0 0 0-4.24.973.973 0 0 1 0-1.42z"/></svg><span>Backlinks</span></a></li><li class="action"><a href="#dokuwiki__top" title="Back to top [t]" rel="nofollow" accesskey="t" class="menuitem top"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8v12z"/></svg><span>Back to top</span></a></li>
|
|
|
|
</ul>
|
|
</li>
|
|
|
|
|
|
</ul>
|
|
<!-- /tools-menu -->
|
|
|
|
<ul class="nav navbar-nav">
|
|
|
|
|
|
<li>
|
|
<span class="dw__actions dw-action-icon">
|
|
<a href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection?do=register" title="Register" rel="nofollow" class="menuitem register btn btn-success navbar-btn"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M15 14c-2.67 0-8 1.33-8 4v2h16v-2c0-2.67-5.33-4-8-4m-9-4V7H4v3H1v2h3v3h2v-3h3v-2m6 2a4 4 0 0 0 4-4 4 4 0 0 0-4-4 4 4 0 0 0-4 4 4 4 0 0 0 4 4z"/></svg><span class=""> Register</span></a><a href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection?do=login&sectok=" title="Log In" rel="nofollow" class="menuitem login btn btn-default navbar-btn"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M10 17.25V14H3v-4h7V6.75L15.25 12 10 17.25M8 2h9a2 2 0 0 1 2 2v16a2 2 0 0 1-2 2H8a2 2 0 0 1-2-2v-4h2v4h9V4H8v4H6V4a2 2 0 0 1 2-2z"/></svg><span class=""> Log In</span></a> </span>
|
|
</li>
|
|
|
|
</ul>
|
|
|
|
|
|
|
|
|
|
</div>
|
|
|
|
</div>
|
|
</div>
|
|
</nav>
|
|
<!-- navbar -->
|
|
<div align="center">
|
|
<script async src="//web.archive.org/web/20230315170826js_/https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
|
|
<!-- BHORG_BOTTOM -->
|
|
<ins class="adsbygoogle" style="display:inline-block;width:728px;height:90px" data-ad-client="ca-pub-4658830517838678" data-ad-slot="1603598940"></ins>
|
|
<script>
|
|
(adsbygoogle = window.adsbygoogle || []).push({});
|
|
</script>
|
|
</div>
|
|
|
|
</header>
|
|
|
|
<a name="dokuwiki__top" id="dokuwiki__top"></a>
|
|
|
|
<main role="main" class="dw-container pb-5 dokuwiki container-fluid mx-5">
|
|
|
|
<div id="dokuwiki__pageheader">
|
|
|
|
|
|
<!-- breadcrumbs -->
|
|
<nav id="dw__breadcrumbs" class="small">
|
|
|
|
<hr/>
|
|
|
|
<div class="dw__youarehere">
|
|
<ol class="breadcrumb" itemscope itemtype="http://schema.org/BreadcrumbList"><li>You are here</li><li itemprop="itemListElement" itemscope itemtype="http://schema.org/ListItem"><a href="/web/20230315170826/https://wiki.bash-hackers.org/start" itemprop="item" title="start"><span itemprop="name"><span class="iconify" data-icon="mdi:home"></span></span></a></li><li itemprop="itemListElement" itemscope itemtype="http://schema.org/ListItem"><a itemprop="item" href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/start" class="wikilink1" title="syntax:start">Syntax</a></li><li class="active" itemprop="itemListElement" itemscope itemtype="http://schema.org/ListItem"><span itemprop="name"><a itemprop="item" href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection" class="wikilink1" title="syntax:redirection">Redirection</a></span></li></ol> </div>
|
|
|
|
<div class="dw__breadcrumbs hidden-print">
|
|
<ol class="breadcrumb"><li>Trace</li> </div>
|
|
|
|
<hr/>
|
|
|
|
</nav>
|
|
<!-- /breadcrumbs -->
|
|
|
|
<p class="text-right">
|
|
<span class="pageId ml-1 label label-primary">syntax:redirection</span> </p>
|
|
|
|
<div id="dw__msgarea" class="small">
|
|
</div>
|
|
|
|
</div>
|
|
|
|
<div class="row">
|
|
|
|
|
|
<article id="dokuwiki__content" class="col-sm-12 col-md-12 " itemscope itemtype="http://schema.org/Article" itemref="dw__license">
|
|
|
|
|
|
<!-- page-tools -->
|
|
<nav id="dw__pagetools" class="hidden-print">
|
|
<div class="tools panel panel-default">
|
|
<ul class="nav nav-stacked nav-pills text-muted">
|
|
<li class="action"><a href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection?do=" title="Show page [v]" rel="nofollow" accesskey="v" class="menuitem show"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M13 9h5.5L13 3.5V9M6 2h8l6 6v12a2 2 0 0 1-2 2H6a2 2 0 0 1-2-2V4c0-1.11.89-2 2-2m9 16v-2H6v2h9m3-4v-2H6v2h12z"/></svg><span>Show page</span></a></li><li class="action"><a href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection?do=revisions" title="Old revisions [o]" rel="nofollow" accesskey="o" class="menuitem revs"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M11 7v5.11l4.71 2.79.79-1.28-4-2.37V7m0-5C8.97 2 5.91 3.92 4.27 6.77L2 4.5V11h6.5L5.75 8.25C6.96 5.73 9.5 4 12.5 4a7.5 7.5 0 0 1 7.5 7.5 7.5 7.5 0 0 1-7.5 7.5c-3.27 0-6.03-2.09-7.06-5h-2.1c1.1 4.03 4.77 7 9.16 7 5.24 0 9.5-4.25 9.5-9.5A9.5 9.5 0 0 0 12.5 2z"/></svg><span>Old revisions</span></a></li><li class="action"><a href="/web/20230315170826/https://wiki.bash-hackers.org/syntax/redirection?do=backlink" title="Backlinks" rel="nofollow" class="menuitem backlink"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M10.59 13.41c.41.39.41 1.03 0 1.42-.39.39-1.03.39-1.42 0a5.003 5.003 0 0 1 0-7.07l3.54-3.54a5.003 5.003 0 0 1 7.07 0 5.003 5.003 0 0 1 0 7.07l-1.49 1.49c.01-.82-.12-1.64-.4-2.42l.47-.48a2.982 2.982 0 0 0 0-4.24 2.982 2.982 0 0 0-4.24 0l-3.53 3.53a2.982 2.982 0 0 0 0 4.24m2.82-4.24c.39-.39 1.03-.39 1.42 0a5.003 5.003 0 0 1 0 7.07l-3.54 3.54a5.003 5.003 0 0 1-7.07 0 5.003 5.003 0 0 1 0-7.07l1.49-1.49c-.01.82.12 1.64.4 2.43l-.47.47a2.982 2.982 0 0 0 0 4.24 2.982 2.982 0 0 0 4.24 0l3.53-3.53a2.982 2.982 0 0 0 0-4.24.973.973 0 0 1 0-1.42z"/></svg><span>Backlinks</span></a></li><li class="action"><a href="#dokuwiki__top" title="Back to top [t]" rel="nofollow" accesskey="t" class="menuitem top"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8v12z"/></svg><span>Back to top</span></a></li> </ul>
|
|
</div>
|
|
</nav>
|
|
<!-- /page-tools -->
|
|
|
|
<div class="panel panel-default px-3 py-2" itemprop="articleBody">
|
|
<div class="page panel-body">
|
|
|
|
|
|
<div class="dw-content-page "><!-- content --><div class="dw-content"><p>
|
|
This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.
|
|
</p>
|
|
<div class="editBox" role="application">
|
|
|
|
<div class="toolbar group">
|
|
<div id="draft__status" class="draft__status"></div>
|
|
<div id="tool__bar" class="tool__bar"></div>
|
|
</div>
|
|
<form id="dw__editform" method="post" action="" accept-charset="utf-8" class=" form-inline"><div class="no">
|
|
<input type="hidden" name="sectok" value=""/><input type="hidden" name="id" value="syntax:redirection"/><input type="hidden" name="rev" value="0"/><input type="hidden" name="date" value="0"/><input type="hidden" name="prefix" value="."/><input type="hidden" name="suffix" value=""/><input type="hidden" name="changecheck" value="b20711f1986cd343aaad44f36e6db417"/><input type="hidden" name="target" value="section"/><textarea name="wikitext" id="wiki__text" dir="auto" class="edit form-control" cols="80" rows="10" tabindex="1" readonly="readonly">
|
|
====== Redirection ======
|
|
|
|
<wrap left todo>Fix me: To be continued</wrap>
|
|
\\
|
|
|
|
Redirection makes it possible to control where the output of a command goes to, and where the input of a command comes from. It's a mighty tool that, together with pipelines, makes the shell powerful. The redirection operators are checked whenever a [[syntax:grammar:parser_exec | simple command is about to be executed]].
|
|
|
|
Under normal circumstances, there are 3 files open, accessible by the file descriptors 0, 1 and 2, all connected to your terminal:
|
|
^Name^FD^Description^
|
|
|''stdin''|0|standard input stream (e.g. keyboard)|
|
|
|''stdout''|1|standard output stream (e.g. monitor)|
|
|
|''stderr''|2|standard error output stream (usually also on monitor)|
|
|
|
|
<wrap center info>The terms "monitor" and "keyboard" refer to the same device, the **terminal** here. Check your preferred UNIX(r)-FAQ for details, I'm too lazy to explain what a terminal is ;-) </wrap>
|
|
|
|
Both, ''stdout'' and ''stderr'' are output file descriptors. Their difference is the **convention** that a program outputs payload on ''stdout'' and diagnostic- and error-messages on ''stderr''. If you write a script that outputs error messages, please make sure you follow this convention!
|
|
|
|
Whenever you **name** such a filedescriptor, i.e. you want to redirect this descriptor, you just use the number:
|
|
<code>
|
|
# this executes the cat-command and redirects its error messages (stderr) to the bit bucket
|
|
cat some_file.txt 2>/dev/null
|
|
</code>
|
|
Whenever you **reference** a descriptor, to point to its current target file, then you use a "''&''" followed by a the descriptor number:
|
|
<code>
|
|
# this executes the echo-command and redirects its normal output (stdout) to the standard error target
|
|
echo "There was an error" 1>&2
|
|
</code>
|
|
|
|
The redirection operation can be **anywhere** in a simple command, so these examples are equivalent:
|
|
<code>
|
|
cat foo.txt bar.txt >new.txt
|
|
cat >new.txt foo.txt bar.txt
|
|
>new.txt cat foo.txt bar.txt
|
|
</code>
|
|
<wrap center important>Every redirection operator takes one or two words as operands. If you have to use operands (e.g. filenames to redirect to) that contain spaces you **must** quote them!</wrap>
|
|
|
|
===== Valid redirection targets and sources =====
|
|
This syntax is recognized whenever a ''TARGET'' or a ''SOURCE'' specification (like below in the details descriptions) is used.
|
|
|
|
^Syntax^Description^
|
|
|''FILENAME''|references a normal, ordinary filename from the filesystem (which can of course be a FIFO, too. Simply everything you can reference in the filesystem)|
|
|
|''&N''|references the current target/source of the filedescriptor ''N'' ("duplicates" the filedescriptor)|
|
|
|''&-''|closes the redirected filedescriptor, useful instead of ''> /dev/null'' constructs (''> &-'')|
|
|
|''/dev/fd/N''|duplicates the filedescriptor ''N'', if ''N'' is a valid integer|
|
|
|''/dev/stdin''|duplicates filedescriptor 0 (''stdin'')|
|
|
|''/dev/stdout''|duplicates filedescriptor 1 (''stdout'')|
|
|
|''/dev/stderr''|duplicates filedescriptor 2 (''stderr'')|
|
|
|''/dev/tcp/HOST/PORT''|assuming ''HOST'' is a valid hostname or IP address, and ''PORT'' is a valid port number or service name: redirect from/to the corresponding TCP socket|
|
|
|''/dev/udp/HOST/PORT''|assuming ''HOST'' is a valid hostname or IP address, and ''PORT'' is a valid port number or service name: redirect from/to the corresponding UDP socket|
|
|
|
|
If a target/source specification fails to open, the whole redirection operation fails. Avoid referencing file descriptors above 9, since you may collide with file descriptors Bash uses internally.
|
|
|
|
|
|
|
|
|
|
===== Redirecting output =====
|
|
<code>
|
|
N > TARGET
|
|
</code>
|
|
|
|
This redirects the file descriptor number ''N'' to the target ''TARGET''. If ''N'' is omitted, ''stdout'' is assumed (FD 1). The ''TARGET'' is **truncated** before writing starts.
|
|
|
|
If the option ''noclobber'' is set with [[commands:builtin:set | the set builtin]], with cause the redirection to fail, when ''TARGET'' names a regular file that already exists. You can manually override that behaviour by forcing overwrite with the redirection operator ''>|'' instead of ''>''.
|
|
|
|
|
|
===== Appending redirected output =====
|
|
<code>
|
|
N >> TARGET
|
|
</code>
|
|
|
|
This redirects the file descriptor number ''N'' to the target ''TARGET''. If ''N'' is omitted, ''stdout'' is assumed (FD 1). The ''TARGET'' is **not truncated** before writing starts.
|
|
|
|
===== Redirecting output and error output =====
|
|
<code>
|
|
&> TARGET
|
|
</code>
|
|
|
|
<code>
|
|
>& TARGET
|
|
</code>
|
|
|
|
This special syntax redirects both, ''stdout'' and ''stderr'' to the specified target. It's **equivalent** to
|
|
<code>
|
|
> TARGET 2>&1
|
|
</code>
|
|
|
|
Since Bash4, there's ''&<nowiki>>>TARGET</nowiki>'', which is equivalent to ''<nowiki>>></nowiki> TARGET 2>&1''.
|
|
|
|
<wrap center important>This syntax is deprecated and should not be used. See the page about [[scripting:obsolete | obsolete and deprecated syntax]].</wrap>
|
|
|
|
|
|
===== Appending redirected output and error output =====
|
|
|
|
To append the cumulative redirection of ''stdout'' and ''stderr'' to a file you simply do
|
|
<code>
|
|
>> FILE 2>&1
|
|
</code>
|
|
|
|
<code>
|
|
&>> FILE
|
|
</code>
|
|
|
|
===== Transporting stdout and stderr through a pipe =====
|
|
<code>
|
|
COMMAND1 2>&1 | COMMAND2
|
|
</code>
|
|
|
|
<code>
|
|
COMMAND1 |& COMMAND2
|
|
</code>
|
|
|
|
|
|
===== Redirecting input =====
|
|
<code>
|
|
N < SOURCE
|
|
</code>
|
|
|
|
The input descriptor ''N'' uses ''SOURCE'' as its data source. If ''N'' is omitted, filedescriptor 0 (''stdin'') is assumed.
|
|
|
|
|
|
===== Here documents =====
|
|
<BOOKMARK:tag_heredoc>
|
|
|
|
<code>
|
|
<<TAG
|
|
...
|
|
TAG
|
|
</code>
|
|
|
|
<code>
|
|
<<-TAG
|
|
...
|
|
TAG
|
|
</code>
|
|
|
|
A here-document is an input redirection using source data specified directly at the command line (or in the script), no "external" source. The redirection-operator ''<nowiki><<</nowiki>'' is used together with a tag ''TAG'' that's used to mark the end of input later:
|
|
|
|
<code>
|
|
# display help
|
|
|
|
cat <<EOF
|
|
Sorry...
|
|
No help available yet for $PROGRAM.
|
|
Hehe...
|
|
EOF
|
|
</code>
|
|
|
|
As you see, substitutions are possible. To be precise, the following substitutions and expansions are performed in the here-document data:
|
|
* [[syntax:pe | Parameter expansion]]
|
|
* [[syntax:expansion:cmdsubst | Command substitution]]
|
|
* [[syntax:expansion:arith | Arithmetic expansion]]
|
|
|
|
You can avoid that by quoting the tag:
|
|
<code>
|
|
cat <<"EOF"
|
|
This won't be expanded: $PATH
|
|
EOF
|
|
</code>
|
|
|
|
Last but not least, if the redirection operator ''<nowiki><<</nowiki>'' is followed by a ''-'' (dash), all **leading TAB** from the document data will be ignored. This might be useful to have optical nice code also when using here-documents.
|
|
|
|
The tag you use **must** be the only word in the line, to be recognized as end-of-here-document marker.
|
|
|
|
<wrap center info>It seems that here-documents (tested on versions ''1.14.7'', ''2.05b'' and ''3.1.17'') are correctly terminated when there is an EOF before the end-of-here-document tag. The reason is unknown, but it seems to be done on purpose. Bash 4 introduced a warning message when end-of-file is seen before the tag is reached.</wrap>
|
|
|
|
|
|
|
|
===== Here strings =====
|
|
|
|
<code>
|
|
<<< WORD
|
|
</code>
|
|
|
|
The here-strings are a variation of the here-documents. The word ''WORD'' is taken for the input redirection:
|
|
|
|
<code>
|
|
cat <<< "Hello world... $NAME is here..."
|
|
</code>
|
|
|
|
Just beware to quote the ''WORD'' if it contains spaces. Otherwise the rest will be given as normal parameters.
|
|
|
|
The here-string will append a newline (''\n'') to the data.
|
|
|
|
===== Multiple redirections =====
|
|
|
|
More redirection operations can occur in a line of course. The order is **important**! They're evaluated from **left to right**.
|
|
If you want to redirect both, ''stderr'' and ''stdout'' to the same file (like ''/dev/null'', to hide it), this is **the wrong way**:
|
|
<code bash>
|
|
# { echo OUTPUT; echo ERRORS >&2; } is to simulate something that outputs to STDOUT and STDERR
|
|
# you can test with it
|
|
{ echo OUTPUT; echo ERRORS >&2; } 2>&1 1>/dev/null
|
|
</code>
|
|
Why? Relatively easy:
|
|
* initially, ''stdout'' points to your terminal (you read it)
|
|
* same applies to ''stderr'', it's connected to your terminal
|
|
* ''2>&1'' redirects ''stderr'' away from the terminal to the target for ''stdout'': **the terminal** (again...)
|
|
* ''1>/dev/null'' redirects ''stdout'' away from your terminal to the file ''/dev/null''
|
|
What remains? ''stdout'' goes to ''/dev/null'', ''stderr'' still (or better: "again") goes to the terminal. You have to swap the order to make it do what you want:
|
|
<code bash>
|
|
{ echo OUTPUT; echo ERRORS >&2; } 1>/dev/null 2>&1
|
|
</code>
|
|
|
|
===== Examples =====
|
|
|
|
How to make a program quiet (assuming all output goes to ''STDOUT'' and ''STDERR''?
|
|
<code>
|
|
command >/dev/null 2>&1
|
|
</code>
|
|
|
|
===== See also =====
|
|
* Internal: [[howto:redirection_tutorial | Illustrated Redirection Tutorial]]
|
|
* Internal: [[commands:builtin:set#tag_noclobber | The noclobber option]]
|
|
* Internal: [[commands:builtin:exec | The exec builtin command]]
|
|
* Internal: [[syntax:grammar:parser_exec | Simple commands parsing and execution]]
|
|
* Internal: [[syntax:expansion:proc_subst | Process substitution syntax]]
|
|
* Internal: [[scripting:obsolete | Obsolete and deprecated syntax]]
|
|
* Internal: [[scripting:nonportable | Nonportable syntax and command uses]]</textarea>
|
|
<div id="wiki__editbar" class="editBar">
|
|
<div id="size__ctl">
|
|
</div>
|
|
</div>
|
|
</div></form>
|
|
</div>
|
|
</div><!-- /content --></div>
|
|
</div>
|
|
</div>
|
|
|
|
<div class="small text-right">
|
|
|
|
<span class="docInfo">
|
|
<!--
|
|
FILE ARCHIVED ON 17:08:26 Mar 15, 2023 AND RETRIEVED FROM THE
|
|
INTERNET ARCHIVE ON 11:36:15 Apr 14, 2023.
|
|
JAVASCRIPT APPENDED BY WAYBACK MACHINE, COPYRIGHT INTERNET ARCHIVE.
|
|
|
|
ALL OTHER CONTENT MAY ALSO BE PROTECTED BY COPYRIGHT (17 U.S.C.
|
|
SECTION 108(a)(3)).
|
|
-->
|
|
<!--
|
|
playback timings (ms):
|
|
captures_list: 988.643
|
|
exclusion.robots: 0.113
|
|
exclusion.robots.policy: 0.105
|
|
cdx.remote: 0.054
|
|
esindex: 0.006
|
|
LoadShardBlock: 961.895 (3)
|
|
PetaboxLoader3.datanode: 960.206 (4)
|
|
load_resource: 340.181
|
|
PetaboxLoader3.resolve: 266.687
|
|
--> |