<div id="readability-page-1" class="page"><div>
    
    <article>
        <ul id="markdown-toc">
  <li><a href="#개요" id="markdown-toc-개요">개요</a></li>
  <li><a href="#builtin-명령과-external-명령" id="markdown-toc-builtin-명령과-external-명령">builtin 명령과 External 명령</a></li>
  <li><a href="#목록" id="markdown-toc-목록">목록</a></li>
  <li><a href="#참고문헌" id="markdown-toc-참고문헌">참고문헌</a></li>
  <li><a href="#주석" id="markdown-toc-주석">주석</a></li>
</ul>

<h2 id="개요">개요</h2>

<p>내부 명령을 사용하는 명령.</p>

<h2 id="builtin-명령과-external-명령">builtin 명령과 External 명령</h2>

<p>가령 [[/cmd/echo]]의 경우, 내부(builtin)와 외부(external) 명령이 모두 존재한다.</p>

<div><pre><code><span>$ </span><span>echo </span>hello
hello

<span>$ </span>which <span>echo</span>
/bin/echo

<span>$ </span>file <span>$(</span>which <span>echo</span><span>)</span>
/bin/echo: Mach-O universal binary with 2 architectures: <span>[</span>x86_64:Mach-O 64-bit executable x86_64] <span>[</span>arm64e:Mach-O 64-bit executable arm64e]
/bin/echo <span>(</span><span>for </span>architecture x86_64<span>)</span>:	Mach-O 64-bit executable x86_64
/bin/echo <span>(</span><span>for </span>architecture arm64e<span>)</span>:	Mach-O 64-bit executable arm64e
</code></pre></div>

<p>위와 같이 <code>which</code>로 조사해 보면 외부 명령인 <code>echo</code>의 정보가 출력된다.</p>

<p><code>echo</code>와 똑같은 이름을 갖는 내부 명령을 사용하려면 <code>builtin</code>을 앞에 붙여 사용하면 된다.</p>

<div><pre><code><span>$ </span><span>builtin echo </span>hello
hello
</code></pre></div>

<p>builtin 명령을 사용하면 external 명령에 비해 시스템 오버헤드가 적으므로 더 빠르게 실행된다.</p>

<div><pre><code><span>$ </span><span>time </span><span>for </span>i <span>in</span> <span>{</span>1..10000<span>}</span><span>;</span> <span>do</span> /bin/echo <span>$i</span> <span>;</span> <span>done</span> <span>&gt;</span> /dev/null

real	0m11.836s
user	0m3.689s
sys	0m6.435s
</code></pre></div>

<ul>
  <li><code>/bin/echo</code> : External 명령인 <code>/bin/echo</code>를 사용.</li>
</ul>

<div><pre><code><span>$ </span><span>time </span><span>for </span>i <span>in</span> <span>{</span>1..10000<span>}</span><span>;</span> <span>do </span><span>builtin echo</span> <span>$i</span> <span>;</span> <span>done</span> <span>&gt;</span> /dev/null

real	0m0.039s
user	0m0.034s
sys	0m0.005s
</code></pre></div>

<ul>
  <li><code>builtin echo</code> : builtin 명령인 <code>echo</code>를 사용.</li>
</ul>

<p>딱히 지정하지 않고 사용하면 기본으로 builtin 명령을 사용하는 것으로 보인다.</p>

<div><pre><code><span>$ </span><span>time </span><span>for </span>i <span>in</span> <span>{</span>1..10000<span>}</span><span>;</span> <span>do </span><span>echo</span> <span>$i</span> <span>;</span> <span>done</span> <span>&gt;</span> /dev/null

real	0m0.035s
user	0m0.028s
sys	0m0.006s
</code></pre></div>

<blockquote>

  <p>외부 명령어는 실행될 때 새로운 프로세스로서 생성됩니다.
이때 OS가 필요한 메모리 영역을 확보하거나 프로세스 목록(프로세스 테이블)을 바꿔 쓰는 등 여러 가지 처리를 수행합니다.
한편, 내부 명령어는 배시 프로그램(C 코드) 안에 구현되어 있으므로,
배시가 내부 명령어를 호출하는 비용은 어떤 프로그램이 자신의 함수를 호출할 때 쓰는 비용과 같습니다.
이것은 프로세스 생성에 비해 매우 가벼운 처리입니다.
따라서 이 에에서는 내부 명령어의 호출이 더 빠르게 완료됩니다.
<sup id="fnref:artof-100" role="doc-noteref"><a href="#fn:artof-100" rel="footnote">1</a></sup></p>
</blockquote>

<h2 id="목록">목록</h2>

<p>다음은 <code>man builtin</code>으로 볼 수 있는 목록이다.</p>

<table>
  <thead>
    <tr>
      <th>Command</th>
      <th>External</th>
      <th>csh(1)</th>
      <th>sh(1)</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>!</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>%</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>.</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>:</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>@</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>[</td>
      <td>Yes</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>{</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>}</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>alias</td>
      <td>No**</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>alloc</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>bg</td>
      <td>No**</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>bind</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>bindkey</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>break</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>breaksw</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>builtin</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>builtins</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>case</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>cd</td>
      <td>No**</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>chdir</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>command</td>
      <td>No**</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>complete</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>continue</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>default</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>dirs</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>do</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>done</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>[[/cmd/echo]]{echo}</td>
      <td>Yes</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>echotc</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>elif</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>else</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>end</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>endif</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>endsw</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>esac</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>eval</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>exec</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>exit</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>export</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>false</td>
      <td>Yes</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>[[/cmd/fc]]{fc}</td>
      <td>No**</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>fg</td>
      <td>No**</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>filetest</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>fi</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>for</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>foreach</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>getopts</td>
      <td>No**</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>glob</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>goto</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>hash</td>
      <td>No**</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>hashstat</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>history</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>hup</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>if</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>jobid</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>jobs</td>
      <td>No**</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>[[/cmd/kill]]{kill}</td>
      <td>Yes</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>limit</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>local</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>log</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>login</td>
      <td>Yes</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>logout</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>ls-F</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>nice</td>
      <td>Yes</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>nohup</td>
      <td>Yes</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>notify</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>onintr</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>popd</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>printenv</td>
      <td>Yes</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>printf</td>
      <td>Yes</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>pushd</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>pwd</td>
      <td>Yes</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>read</td>
      <td>No**</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>readonly</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>rehash</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>repeat</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>return</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>sched</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>set</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>setenv</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>settc</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>setty</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>setvar</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>shift</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>source</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>stop</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>suspend</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>switch</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>telltc</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>test</td>
      <td>Yes</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>then</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>time</td>
      <td>Yes</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>times</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>trap</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>true</td>
      <td>Yes</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>type</td>
      <td>No**</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>ulimit</td>
      <td>No**</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>umask</td>
      <td>No**</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>unalias</td>
      <td>No**</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>uncomplete</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>unhash</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>unlimit</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>unset</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>unsetenv</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>until</td>
      <td>No</td>
      <td>No</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>wait</td>
      <td>No**</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
    <tr>
      <td>where</td>
      <td>No</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>which</td>
      <td>Yes</td>
      <td>Yes</td>
      <td>No</td>
    </tr>
    <tr>
      <td>while</td>
      <td>No</td>
      <td>Yes</td>
      <td>Yes</td>
    </tr>
  </tbody>
</table>

<h2 id="참고문헌">참고문헌</h2>

<ul>
  <li>아트 오브 셸 원라이너 160제 - 우에다 류이치, 야마다 야스히로, 다시로 가쓰야, 나카무라 소이치, 이마이즈미 미쓰유키 저 외 2명 정보 더 보기/감추기 / 제이펍 / 1쇄 발행: 2023년 03월 13일 / 원제: 1日1問、半年以内に習得 シェル・ワンライナー160本ノック</li>
</ul>

<h2 id="주석">주석</h2>



    </article>


    
    
    



</div></div>

Shell builtin 명령어

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