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<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><link href=https://flokoe.github.io/bash-hackers-wiki/syntax/expansion/tilde/ rel=canonical><link href=../proc_subst/ rel=prev><link href=../wordsplit/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.5.44"><title>Tilde expansion - The Bash Hackers Wiki</title><link rel=stylesheet href=../../../assets/stylesheets/main.0253249f.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.06af60db.min.css><link rel=preconnect href=https://fonts.gstatic.com crossorigin><link rel=stylesheet href="https://fonts.googleapis.com/css?family=Roboto:300,300i,400,400i,700,700i%7CRoboto+Mono:400,400i,700,700i&display=fallback"><style>:root{--md-text-font:"Roboto";--md-code-font:"Roboto Mono"}</style><script>__md_scope=new URL("../../..",location),__md_hash=e=>[...e].reduce(((e,_)=>(e<<5)-e+_.charCodeAt(0)),0),__md_get=(e,_=localStorage,t=__md_scope)=>JSON.parse(_.getItem(t.pathname+"."+e)),__md_set=(e,_,t=localStorage,a=__md_scope)=>{try{t.setItem(a.pathname+"."+e,JSON.stringify(_))}catch(e){}}</script></head> <body dir=ltr data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo> <input class=md-toggle data-md-toggle=drawer type=checkbox id=__drawer autocomplete=off> <input class=md-toggle data-md-toggle=search type=checkbox id=__search autocomplete=off> <label class=md-overlay for=__drawer></label> <div data-md-component=skip> <a href=#tilde-expansion class=md-skip> Skip to content </a> </div> <div data-md-component=announce> </div> <header class=md-header data-md-component=header> <nav class="md-header__inner md-grid" aria-label=Header> <a href=../../.. title="The Bash Hackers Wiki" class="md-header__button md-logo" aria-label="The Bash Hackers Wiki" data-md-component=logo> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54"/></svg> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> The Bash Hackers Wiki </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> Tilde expansion </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media data-md-color-scheme=default data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to dark mode" type=radio name=__palette id=__palette_0> <label class="md-header__button md-icon" title="Switch to dark mode" for=__palette_1 hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a4 4 0 0 0-4 4 4 4 0 0 0 4 4 4 4 0 0 0 4-4 4 4 0 0 0-4-4m0 10a6 6 0 0 1-6-6 6 6 0 0 1 6-6 6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg> </label> <input class=md-option data-md-color-media data-md-color-scheme=slate data-md-color-primary=indigo data-md-color-accent=indigo aria-label="Switch to light mode" type=radio name=__palette id=__palette_1> <label class="md-header__button md-icon" title="Switch to light mode" for=__palette_0 hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 18c-.89 0-1.74-.2-2.5-.55C11.56 16.5 13 14.42 13 12s-1.44-4.5-3.5-5.45C10.26 6.2 11.11 6 12 6a6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg> </label> </form> <script>var palette=__md_get("__palette");if(palette&&palette.color){if("(prefers-color-scheme)"===palette.color.media){var media=matchMedia("(pre
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~/...
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~NAME
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~NAME/...
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~+
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~+/...
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~-
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~-/...
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</code></pre></div> <p>The tilde expansion is used to expand to several specific pathnames:</p> <ul> <li>home directories</li> <li>current working directory</li> <li>previous working directory</li> </ul> <p>Tilde expansion is only performed, when the tilde-construct is at the beginning of a word, or a separate word.</p> <p>If there's nothing to expand, i.e., in case of a wrong username or any other error condition, the tilde construct is not replaced, it stays what it is.</p> <p>Tilde expansion is also performed everytime a variable is assigned:</p> <ul> <li>after the <strong>first</strong> <code>=</code>: <code>TARGET=~moonman/share</code></li> <li>after <strong>every</strong> <code>:</code> (colon) in the assigned value: <code>TARGET=file:~moonman/share</code></li> </ul> <div class="admonition info"> <p class=admonition-title>Note</p> <p>As of now (Bash 4.3-alpha) the following constructs <strong>also</strong> works, though it's not a variable assignment:</p> <div class=highlight><pre><span></span><code>echo foo=~
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echo foo=:~
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</code></pre></div> <p>I don't know yet, if this is a bug or intended.</p> </div> <p>This way you can correctly use the tilde expansion in your <a href=../../shellvars/#PATH>PATH</a>:</p> <div class=highlight><pre><span></span><code>PATH=~/mybins:~peter/mybins:$PATH
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</code></pre></div> <p><strong>Spaces in the referenced pathes?</strong> A construct like...</p> <div class=highlight><pre><span></span><code>~/"my directory"
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</code></pre></div> <p>...is perfectly valid and works!</p> <h2 id=home-directory>Home directory<a class=headerlink href=#home-directory title="Permanent link">¶</a></h2> <div class=highlight><pre><span></span><code>~
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~<NAME>
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</code></pre></div> <p>This form expands to the home-directory of the current user (<code>~</code>) or the home directory of the given user (<code>~<NAME></code>).</p> <p>If the given user doesn't exist (or if his home directory isn't determinable, for some reason), it doesn't expand to something else, it stays what it is. The requested home directory is found by asking the operating system for the associated home directory for <code><NAME></code>.</p> <p>To find the home directory of the current user (<code>~</code>), Bash has a precedence:</p> <ul> <li>expand to the value of <a href=../../shellvars/#HOME>HOME</a> if it's defined</li> <li>expand to the home directory of the user executing the shell (operating system)</li> </ul> <p>That means, the variable <code>HOME</code> can override the "real" home directory, at least regarding tilde expansion.</p> <h2 id=current-working-directory>Current working directory<a class=headerlink href=#current-working-directory title="Permanent link">¶</a></h2> <div class=highlight><pre><span></span><code>~+
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</code></pre></div> <p>This expands to the value of the <a href=../../shellvars/#PWD>PWD</a> variable, which holds the currect working directory:</p> <div class=highlight><pre><span></span><code>echo "CWD is $PWD"
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</code></pre></div> <p>is equivalent to (note it <strong>must</strong> be a separate word!):</p> <div class=highlight><pre><span></span><code>echo "CWD is" ~+
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</code></pre></div> <h2 id=previous-working-directory>Previous working directory<a class=headerlink href=#previous-working-directory title="Permanent link">¶</a></h2> <div class=highlight><pre><span></span><code>~-
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</code></pre></div> <p>This expands to the value of the <a href=../../shellvars/#OLDPWD>OLDPWD</a> variable, which holds the previous working directory (the one before the last <code>cd</code>). If <code>OLDPWD</code> is unset (never changed the directory), it is not expanded.</p> <div class=highlight><pre><span></span><code>$ pwd
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/home/bash
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$ cd /etc
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$ echo ~-
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/home/bash
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</code></pre></div> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">¶</a></h2> <ul> <li>Internal: <a href=../intro/ >Introduction to expansion and substitution</a></li> </ul> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date">November 13, 2024</span> </span> <span class=md-source-file__fact> <span class=md-icon title=Created> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M14.47 15.08 11 13V7h1.5v5.25l3.08 1.83c-.41.28-.79.62-1.11 1m-1.39 4.84c-.36.05-.71.08-1.08.08-4.42 0-8-3.58-8-8s3.58-8 8-8 8 3.58 8 8c0 .37-.03.72-.08 1.08.69.1 1.33.32 1.92.64.1-.56.16-1.13.16-1.72 0-5.5-4.5-10-10-10S2 6.5 2 12s4.47 10 10 10c.59 0 1.16-.06 1.72-.16-.32-.59-.54-1.23-.64-1.92M18 15v3h-3v2h3v3h2v-3h3v-2h-3v-3z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date">November 13, 2024</span> </span> </aside> <h2 id=__comments>Comments</h2> <script src=https://giscus.app/client.js data-repo=flokoe/bash-hackers-wiki data-repo-id=R_kgDOJ3Nr6Q data-category="Giscus Page Comments" data-category-id=DIC_kwDOJ3Nr6c4CXq9t data-mapping=pathname data-strict=1 data-reactions-enabled=1 data-emit-metadata=0 data-input-position=top data-theme=preferred_color_scheme data-lang=en data-loading=lazy crossorigin=anonymous async>
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