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                        <h2 id="macros-for-running-shell-commands">Macros for running shell commands</h2>
<p>&#xAE30;&#xBCF8;&#xC801;&#xC73C;&#xB85C; &#xB9E4;&#xD06C;&#xB85C;&#xC5D0; <code>()</code> &#xAC00; &#xC5C6;&#xC73C;&#xBA74; &#xB9E4;&#xD06C;&#xB85C;&#xB85C; &#xC778;&#xC2DD;&#xB418;&#xC9C0; &#xC54A;&#xC2B5;&#xB2C8;&#xB2E4;.</p>
<h3 id="determining-the-platform">Determining the platform</h3>
<p>&#xD604;&#xC7AC; m4 &#xAC00; &#xC2E4;&#xD589;&#xB418;&#xB294; platform &#xC744; &#xC54C; &#xC218; &#xC788;&#xAC8C; &#xB2E4;&#xC74C;&#xACFC; &#xAC19;&#xC740; optional builtin &#xB9E4;&#xD06C;&#xB85C;&#xAC00; &#xC81C;&#xACF5;&#xB429;&#xB2C8;&#xB2E4;.
&#xB9E4;&#xD06C;&#xB85C;&#xAC00; &#xC815;&#xC758;&#xB418;&#xC5B4; &#xC788;&#xB294;&#xC9C0;&#xB294; <code>ifdef</code> &#xC744; &#xC774;&#xC6A9;&#xD574; &#xD14C;&#xC2A4;&#xD2B8;&#xD560; &#xC218; &#xC788;&#xACE0;, 
&#xC815;&#xC758;&#xB418;&#xC5B4; &#xC788;&#xC744; &#xACBD;&#xC6B0; &#xD655;&#xC7A5;&#xC740; empty &#xC2A4;&#xD2B8;&#xB9C1;&#xC774; &#xB429;&#xB2C8;&#xB2E4;.
&#xB2E4;&#xC74C;&#xC740; linux &#xC5D0;&#xC11C; &#xC2E4;&#xD589;&#xD55C; &#xACB0;&#xACFC;&#xC778;&#xB370;  <code>__gnu__</code> &#xC640; <code>__unix__</code> &#xB9E4;&#xD06C;&#xB85C;&#xAC00; &#xC124;&#xC815;&#xB41C; &#xAC83;&#xC744; &#xC54C; &#xC218; &#xC788;&#xC2B5;&#xB2C8;&#xB2E4;.</p>
<pre><code>$ m4 &lt;&lt;\@
Optional builtin: __gnu__             
Optional builtin: __os2__
Optional builtin: os2
Optional builtin: __unix__
Optional builtin: unix
Optional builtin: __windows__
Optional builtin: windows
@

Optional builtin:                 &lt;---- empty string
Optional builtin: __os2__
Optional builtin: os2
Optional builtin:                 &lt;---- empty string
Optional builtin: unix
Optional builtin: __windows__
Optional builtin: windows
-------------------------------

$ m4 &lt;&lt;\@
define(`provided&apos;, `0&apos;)
ifdef(`__unix__&apos;, `define(`provided&apos;, incr(provided))&apos;)

provided
@

1
</code></pre><h3 id="syscmd">syscmd</h3>
<blockquote>
<p><strong>syscmd</strong> ( <em>shell-command</em> )<br>&#xB9E4;&#xD06C;&#xB85C;&#xC758; &#xD655;&#xC7A5; &#xACB0;&#xACFC;&#xB294; void &#xC785;&#xB2C8;&#xB2E4;.</p>
</blockquote>
<p>&#xC778;&#xC218;&#xB85C; &#xC8FC;&#xC5B4;&#xC9C4; <code>shell-command</code> &#xB97C; <code>sh -c</code> &#xC744; &#xC774;&#xC6A9;&#xD574; &#xC2E4;&#xD589;&#xC2DC;&#xD0B5;&#xB2C8;&#xB2E4;.
&#xC774;&#xB54C; STDIN, STDOUT, STDERR &#xB294; &#xD604;&#xC7AC; &#xC2E4;&#xD589; &#xC911;&#xC778; m4 &#xC640; &#xAC19;&#xC2B5;&#xB2C8;&#xB2E4;.
&#xB9E4;&#xD06C;&#xB85C;&#xC758; &#xD655;&#xC7A5; &#xACB0;&#xACFC;&#xB294; void &#xC774;&#xBBC0;&#xB85C; <code>shell-command</code> &#xC758; &#xCD9C;&#xB825;&#xC744;
&#xB9E4;&#xD06C;&#xB85C; &#xAC12;&#xC73C;&#xB85C; &#xC0AC;&#xC6A9;&#xD558;&#xB824;&#xBA74; <code>esyscmd</code> &#xB9E4;&#xD06C;&#xB85C;&#xB97C; &#xC0AC;&#xC6A9;&#xD574;&#xC57C; &#xD569;&#xB2C8;&#xB2E4;.</p>
<h3 id="esyscmd">esyscmd</h3>
<blockquote>
<p><strong>esyscmd</strong> ( <em>shell-command</em> )</p>
</blockquote>
<p><code>esyscmd</code> &#xB9E4;&#xD06C;&#xB85C;&#xC758; &#xD655;&#xC7A5; &#xACB0;&#xACFC;&#xB294; <code>shell-command</code> &#xC758; STDOUT &#xAC12;&#xC774; &#xB429;&#xB2C8;&#xB2E4;.
&#xB530;&#xB77C;&#xC11C; &#xB9E4;&#xD06C;&#xB85C;&#xB97C; &#xC815;&#xC758;&#xD560; &#xB54C; &#xAC12;&#xC73C;&#xB85C; &#xC0AC;&#xC6A9;&#xD560; &#xC218; &#xC788;&#xC2B5;&#xB2C8;&#xB2E4;.
STDERR &#xCD9C;&#xB825;&#xC740; &#xAC12;&#xC5D0; &#xD3EC;&#xD568;&#xB418;&#xC9C0; &#xC54A;&#xC2B5;&#xB2C8;&#xB2E4;.</p>
<p>&#xBA85;&#xB839; &#xCD9C;&#xB825; &#xACB0;&#xACFC; trailing newline &#xC744; &#xC81C;&#xAC70;&#xD558;&#xB824;&#xBA74; &#xB2E4;&#xC74C;&#xACFC; &#xAC19;&#xC774;&#xD558;&#xBA74; &#xB429;&#xB2C8;&#xB2E4;.</p>
<pre><code>$ m4 &lt;&lt;\@        
define(`current_date&apos;, `esyscmd(`date&apos;)&apos;)
{{ current_date }}
@

{{ Fri Jul 31 13:10:48 KST 2020     &lt;---- newline &#xC774; &#xD3EC;&#xD568;&#xB41C;&#xB2E4;.
 }}

$ m4 &lt;&lt;\@        
define(`current_date&apos;, `esyscmd(`date | sed -Ez &quot;s/\\n+$//&quot;&apos;)&apos;)
{{ current_date }}
@

{{ Fri Jul 31 13:10:52 KST 2020 }}
</code></pre><p>&#xAE30;&#xBCF8;&#xC801;&#xC73C;&#xB85C; esyscmd &#xB9E4;&#xD06C;&#xB85C; &#xD655;&#xC7A5; &#xACB0;&#xACFC;&#xB294; quote &#xC774; &#xB418;&#xC9C0; &#xC54A;&#xAE30; &#xB54C;&#xBB38;&#xC5D0;
shell-command &#xC758; &#xCD9C;&#xB825;&#xC5D0; &#xB9E4;&#xCE6D;&#xB418;&#xB294; &#xB9E4;&#xD06C;&#xB85C;&#xAC00; &#xC874;&#xC7AC;&#xD560; &#xACBD;&#xC6B0; &#xD655;&#xC7A5;&#xB420; &#xC218; &#xC788;&#xC2B5;&#xB2C8;&#xB2E4;.
&#xB2E4;&#xC74C;&#xC744; &#xBCF4;&#xBA74; <code>KST</code> &#xB9E4;&#xD06C;&#xB85C;&#xAC00; &#xB9E4;&#xCE6D;&#xC774; &#xB418;&#xC5B4; date &#xBA85;&#xB839;&#xC758; &#xCD9C;&#xB825;&#xC774; <code>XXX</code> &#xB85C; 
&#xBCC0;&#xACBD;&#xB41C; &#xAC83;&#xC744; &#xBCFC; &#xC218; &#xC788;&#xC2B5;&#xB2C8;&#xB2E4;.</p>
<pre><code>$ m4 &lt;&lt;\@        
define(`KST&apos;, `XXX&apos;)
define(`current_date&apos;, `esyscmd(`date | sed -Ez &quot;s/\\n+$//&quot;&apos;)&apos;)
{{ current_date }}
@

{{ Fri Jul 31 05:11:21 XXX 2020 }}       # KST &#xAC00; XXX &#xB85C; &#xBCC0;&#xACBD;&#xB428;.
</code></pre><p>&#xC774;&#xAC83;&#xC744; &#xBC29;&#xC9C0;&#xD558;&#xB824;&#xBA74; &#xB2E4;&#xC74C;&#xACFC; &#xAC19;&#xC774; shell-command &#xC758; &#xCD9C;&#xB825;&#xC5D0; m4 quotes &#xC744; &#xCD94;&#xAC00;&#xD574; &#xC8FC;&#xBA74; &#xB429;&#xB2C8;&#xB2E4;.</p>
<pre><code>$ m4 &lt;&lt;\@        
define(`KST&apos;, `XXX&apos;)              
define(`current_date&apos;, `esyscmd(`date | sed -Ez -e &quot;s/\\n+$//&quot; -e &quot;s/^/\`/;s/$/&apos;/&quot;&apos;)&apos;)
{{ current_date }}                 # sed &#xC2A4;&#xD06C;&#xB9BD;&#xD2B8; &#xC791;&#xC131;&#xC5D0; double quotes &#xC774; &#xC0AC;&#xC6A9;&#xB410;&#xC73C;&#xBBC0;&#xB85C;
@                                  # \\n &#xC640; \` (&#xBA85;&#xB839;&#xCE58;&#xD658;) &#xB97C; escape &#xD574;&#xC57C;&#xD569;&#xB2C8;&#xB2E4;.

{{ Fri Jul 31 05:12:22 KST 2020 }}
</code></pre><h3 id="sysval">sysval</h3>
<p><code>syscmd</code>, <code>esyscmd</code> &#xB9E4;&#xD06C;&#xB85C;&#xC5D0; &#xC758;&#xD574; &#xC2E4;&#xD589;&#xB41C; shell-command &#xC758; &#xC885;&#xB8CC; &#xC0C1;&#xD0DC; &#xAC12;&#xC785;&#xB2C8;&#xB2E4;.
&#xAE30;&#xBCF8;&#xAC12;&#xC740; <code>0</code> &#xC785;&#xB2C8;&#xB2E4;.</p>
<pre><code>$ m4 &lt;&lt;\@                                  $ m4 &lt;&lt;\@
syscmd(`date&apos;)                             syscmd(`date -@&apos;)
sysval                                     sysval
@                                          @
Thu Jul 30 20:12:38 KST 2020               date: invalid option -- &apos;@&apos;
                                           Try &apos;date --help&apos; for more information.
0    # &#xC815;&#xC0C1; &#xC885;&#xB8CC;                                     
                                           1     # &#xC624;&#xB958;
</code></pre><h3 id="mkstemp">mkstemp</h3>
<blockquote>
<p><strong>mkstemp</strong> ( <em>Template</em> )   </p>
</blockquote>
<p>shell &#xC758; mktemp &#xBA85;&#xB839;&#xCC98;&#xB7FC; &#xC784;&#xC2DC;&#xD30C;&#xC77C;&#xC744; &#xB9CC;&#xB4E4;&#xC5B4;&#xC8FC;&#xB294; &#xB9E4;&#xD06C;&#xB85C;&#xC785;&#xB2C8;&#xB2E4;.
<code>Template</code> &#xC744; &#xC9C0;&#xC815;&#xD558;&#xC9C0; &#xC54A;&#xC73C;&#xBA74; &#xAE30;&#xBCF8;&#xC801;&#xC73C;&#xB85C; &#xD604;&#xC7AC; &#xB514;&#xB809;&#xD1A0;&#xB9AC;&#xC5D0; &#xC0DD;&#xC131;&#xD569;&#xB2C8;&#xB2E4;.
( &#xD655;&#xC7A5; &#xACB0;&#xACFC;&#xB294; quote &#xC774; &#xB429;&#xB2C8;&#xB2E4;.)</p>
<pre><code>$ m4 &lt;&lt;\@                               
mkstemp()
mkstemp(`/tmp/XXXXXXXXXX&apos;)
mkstemp(`/tmp/foo-XX&apos;)
mkstemp(`/tmp/foo-&apos;)
@
kq9VZK
/tmp/XXXXh4h8SK
/tmp/foo-ePf8cK
/tmp/foo-rX01nL

$ ls ./kq9VZK /tmp/XXXXh4h8SK /tmp/foo-*
./kq9VZK  /tmp/XXXXh4h8SK  /tmp/foo-ePf8cK  /tmp/foo-rX01nL
</code></pre><p><code>Template</code> &#xC5D0; &#xC0AC;&#xC6A9;&#xB418;&#xB294; <code>X</code> &#xC758; &#xAC1C;&#xC218;&#xB294; 6 &#xAC1C;&#xB85C; &#xC815;&#xD574;&#xC838; &#xC788;&#xC2B5;&#xB2C8;&#xB2E4;.
&#xADF8;&#xB7EC;&#xBBC0;&#xB85C; &#xB2E4;&#xC74C;&#xACFC; &#xAC19;&#xC774; <code>XX</code> &#xB450; &#xAC1C;&#xB97C; &#xC0AC;&#xC6A9;&#xD574;&#xB3C4; &#xCD5C;&#xC885; &#xACB0;&#xACFC;&#xB294; &#xB79C;&#xB364; &#xBB38;&#xC790;&#xAC00; 6 &#xAC1C;&#xAC00; &#xB429;&#xB2C8;&#xB2E4;.</p>
<pre><code>$ m4 &lt;&lt;\@
maketemp(`foo-XX&apos;)
ifelse( esyscmd(`echo \`foo-??????\&apos;&apos;), `foo-??????&apos;, `no file&apos;, `created&apos;)
@

foo-iDCkBt        # echo &#xBA85;&#xB839;&#xC5D0; &#xC0AC;&#xC6A9;&#xB41C; \` &#xC640; \&apos; &#xB294; 
created           # esyscmd &#xB9E4;&#xD06C;&#xB85C; &#xD655;&#xC7A5; &#xACB0;&#xACFC;&#xC5D0; m4 quotes &#xC744; &#xCD94;&#xAC00;&#xD558;&#xAE30; &#xC704;&#xD55C; &#xAC83;&#xC785;&#xB2C8;&#xB2E4;.
</code></pre><pre><code>$ m4 &lt;&lt;\@                               
define(`file1&apos;, mkstemp(`foo-XX&apos;))dnl
define(`file2&apos;, mkstemp(`foo-XXXXXX&apos;))dnl

ifelse( len(defn(`file1&apos;)), len(defn(`file2&apos;)), `same length&apos;, `different&apos;)
ifelse( defn(`file1&apos;), defn(`file2&apos;), `same&apos;, `different file&apos;)

syscmd(`rm &apos;defn(`file1&apos;) defn(`file2&apos;))
sysval
@

same length
different file
0
</code></pre>
                    
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