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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/misc/readthesourceluke/ rel=canonical><link href=../bashphorisms/ rel=prev><link href=../shell_humor/ rel=next><link rel=icon href=../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.5.44"><title>Readthesourceluke - 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> </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> Readthesourceluke </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("(prefers-color-scheme: light)"),input=document.querySelector(media.match
<a id=__codelineno-0-2 name=__codelineno-0-2 href=#__codelineno-0-2></a><span class=cm> the paranoids dream ability of telling you when someone has read your</span>
<a id=__codelineno-0-3 name=__codelineno-0-3 href=#__codelineno-0-3></a><span class=cm> mail, it can just as easily be used to tell you when someones .profile</span>
<a id=__codelineno-0-4 name=__codelineno-0-4 href=#__codelineno-0-4></a><span class=cm> file has been read, thus letting one know when someone else has logged</span>
<a id=__codelineno-0-5 name=__codelineno-0-5 href=#__codelineno-0-5></a><span class=cm> in. Pretty good, huh? */</span>
</code></pre></div> <p>From <code>builtins/read.def</code>:</p> <div class=highlight><pre><span></span><code><a id=__codelineno-1-1 name=__codelineno-1-1 href=#__codelineno-1-1></a><span class=w> </span><span class=cm>/* If there are no variables, save the text of the line read to the</span>
<a id=__codelineno-1-2 name=__codelineno-1-2 href=#__codelineno-1-2></a><span class=cm> variable $REPLY. ksh93 strips leading and trailing IFS whitespace,</span>
<a id=__codelineno-1-3 name=__codelineno-1-3 href=#__codelineno-1-3></a><span class=cm> so that `read x ; echo &quot;$x&quot;&#39; and `read ; echo &quot;$REPLY&quot;&#39; behave the</span>
<a id=__codelineno-1-4 name=__codelineno-1-4 href=#__codelineno-1-4></a><span class=cm> same way, but I believe that the difference in behaviors is useful</span>
<a id=__codelineno-1-5 name=__codelineno-1-5 href=#__codelineno-1-5></a><span class=cm> enough to not do it. Without the bash behavior, there is no way</span>
<a id=__codelineno-1-6 name=__codelineno-1-6 href=#__codelineno-1-6></a><span class=cm> to read a line completely without interpretation or modification</span>
<a id=__codelineno-1-7 name=__codelineno-1-7 href=#__codelineno-1-7></a><span class=cm> unless you mess with $IFS (e.g., setting it to the empty string).</span>
<a id=__codelineno-1-8 name=__codelineno-1-8 href=#__codelineno-1-8></a><span class=cm> If you disagree, change the occurrences of `#if 0&#39; to `#if 1&#39; below. */</span>
</code></pre></div> <p>from <code>variables.c</code>:</p> <div class=highlight><pre><span></span><code><a id=__codelineno-2-1 name=__codelineno-2-1 href=#__codelineno-2-1></a><span class=w> </span><span class=cm>/*</span>
<a id=__codelineno-2-2 name=__codelineno-2-2 href=#__codelineno-2-2></a><span class=cm> * 24 October 2001</span>
<a id=__codelineno-2-3 name=__codelineno-2-3 href=#__codelineno-2-3></a><span class=cm> *</span>
<a id=__codelineno-2-4 name=__codelineno-2-4 href=#__codelineno-2-4></a><span class=cm> * I&#39;m tired of the arguing and bug reports. Bash now leaves SSH_CLIENT</span>
<a id=__codelineno-2-5 name=__codelineno-2-5 href=#__codelineno-2-5></a><span class=cm> * and SSH2_CLIENT alone. I&#39;m going to rely on the shell_level check in</span>
<a id=__codelineno-2-6 name=__codelineno-2-6 href=#__codelineno-2-6></a><span class=cm> * isnetconn() to avoid running the startup files more often than wanted.</span>
<a id=__codelineno-2-7 name=__codelineno-2-7 href=#__codelineno-2-7></a><span class=cm> * That will, of course, only work if the user&#39;s login shell is bash, so</span>
<a id=__codelineno-2-8 name=__codelineno-2-8 href=#__codelineno-2-8></a><span class=cm> * I&#39;ve made that behavior conditional on SSH_SOURCE_BASHRC being defined</span>
<a id=__codelineno-2-9 name=__codelineno-2-9 href=#__codelineno-2-9></a><span class=cm> * in config-top.h.</span>
<a id=__codelineno-2-10 name=__codelineno-2-10 href=#__codelineno-2-10></a><span class=cm> */</span>
</code></pre></div> <p>From <code>shell.h</code>:</p> <div class=highlight><pre><span></span><code><a id=__codelineno-3-1 name=__codelineno-3-1 href=#__codelineno-3-1></a><span class=cm>/* Values that can be returned by execute_command (). */</span>
<a id=__codelineno-3-2 name=__codelineno-3-2 href=#__codelineno-3-2></a><span class=cp>#define EXECUTION_FAILURE 1</span>
<a id=__codelineno-3-3 name=__codelineno-3-3 href=#__codelineno-3-3></a><span class=cp>#define EXECUTION_SUCCESS 0</span>
<a id=__codelineno-3-4 name=__codelineno-3-4 href=#__codelineno-3-4></a>
<a id=__codelineno-3-5 name=__codelineno-3-5 href=#__codelineno-3-5></a><span class=cm>/* Usage messages by builtins result in a return status of 2. */</span>
<a id=__codelineno-3-6 name=__codelineno-3-6 href=#__codelineno-3-6></a><span class=cp>#define EX_BADUSAGE 2</span>
<a id=__codelineno-3-7 name=__codelineno-3-7 href=#__codelineno-3-7></a>
<a id=__codelineno-3-8 name=__codelineno-3-8 href=#__codelineno-3-8></a><span class=cm>/* Special exit statuses used by the shell, internally and externally. */</span>
<a id=__codelineno-3-9 name=__codelineno-3-9 href=#__codelineno-3-9></a><span class=cp>#define EX_RETRYFAIL 124</span>
<a id=__codelineno-3-10 name=__codelineno-3-10 href=#__codelineno-3-10></a><span class=cp>#define EX_WEXPCOMSUB 125</span>
<a id=__codelineno-3-11 name=__codelineno-3-11 href=#__codelineno-3-11></a><span class=cp>#define EX_BINARY_FILE 126</span>
<a id=__codelineno-3-12 name=__codelineno-3-12 href=#__codelineno-3-12></a><span class=cp>#define EX_NOEXEC 126</span>
<a id=__codelineno-3-13 name=__codelineno-3-13 href=#__codelineno-3-13></a><span class=cp>#define EX_NOINPUT 126</span>
<a id=__codelineno-3-14 name=__codelineno-3-14 href=#__codelineno-3-14></a><span class=cp>#define EX_NOTFOUND 127</span>
<a id=__codelineno-3-15 name=__codelineno-3-15 href=#__codelineno-3-15></a>
<a id=__codelineno-3-16 name=__codelineno-3-16 href=#__codelineno-3-16></a><span class=cp>#define EX_SHERRBASE 256 </span><span class=cm>/* all special error values are &gt; this. */</span>
<a id=__codelineno-3-17 name=__codelineno-3-17 href=#__codelineno-3-17></a>
<a id=__codelineno-3-18 name=__codelineno-3-18 href=#__codelineno-3-18></a><span class=cp>#define EX_BADSYNTAX 257 </span><span class=cm>/* shell syntax error */</span>
<a id=__codelineno-3-19 name=__codelineno-3-19 href=#__codelineno-3-19></a><span class=cp>#define EX_USAGE 258 </span><span class=cm>/* syntax error in usage */</span>
<a id=__codelineno-3-20 name=__codelineno-3-20 href=#__codelineno-3-20></a><span class=cp>#define EX_REDIRFAIL 259 </span><span class=cm>/* redirection failed */</span>
<a id=__codelineno-3-21 name=__codelineno-3-21 href=#__codelineno-3-21></a><span class=cp>#define EX_BADASSIGN 260 </span><span class=cm>/* variable assignment error */</span>
<a id=__codelineno-3-22 name=__codelineno-3-22 href=#__codelineno-3-22></a><span class=cp>#define EX_EXPFAIL 261 </span><span class=cm>/* word expansion failed */</span>
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