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	<title>chys&#039;s random notes &#187; compression</title>
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	<description>Study more problems; Talk less of isms.</description>
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		<title>Extract Deb files from command line</title>
		<link>http://en.chys.info/2010/02/extract-deb-files/</link>
		<comments>http://en.chys.info/2010/02/extract-deb-files/#comments</comments>
		<pubDate>Mon, 01 Feb 2010 16:15:12 +0000</pubDate>
		<dc:creator>chys</dc:creator>
				<category><![CDATA[Uncategorized]]></category>
		<category><![CDATA[compression]]></category>
		<category><![CDATA[Debian]]></category>
		<category><![CDATA[Gentoo]]></category>
		<category><![CDATA[Linux]]></category>

		<guid isPermaLink="false">http://en.chys.info/?p=739</guid>
		<description><![CDATA[Debian and its derivatives use the .deb format to distribute their packages. To extract them, use ar &#8211; Yes, the very program we programmers use to make static libraries. ar x sudo_1.6.9p17-2_i386.deb Or we can directly extract things from data.tar.gz contained in the .deb file: ar p sudo_1.6.9p17-2_i386.deb data.tar.gz &#124; tar -xzf - No longer [...]<hr/>
Related posts:<ol>
<li><a href='http://en.chys.info/2010/12/concatenate-pdf-files-in-linux/' rel='bookmark' title='Concatenate PDF files in Linux'>Concatenate PDF files in Linux</a></li>
</ol>]]></description>
			<content:encoded><![CDATA[<p><a href="http://www.debian.org">Debian</a> and its derivatives use the <code>.deb</code> format to distribute their packages. To extract them, use <code>ar</code> &#8211; Yes, the very program we programmers use to make static libraries.</p>
<blockquote><p><code>ar x sudo_1.6.9p17-2_i386.deb</code></p></blockquote>
<p>Or we can directly extract things from <code>data.tar.gz</code> contained in the <code>.deb</code> file:</p>
<blockquote><p><code>ar p sudo_1.6.9p17-2_i386.deb data.tar.gz | tar -xzf -</code></p></blockquote>
<p>No longer a user of Debian GNU/Linux, I still have to remember how to extract <code>.deb</code> files. I frequently need to cross-compile a 64-bit version of my program on a 32-bit system, and vice versa; but I don&#8217;t want to cross-compile by myself so many libraries on which my program depends. Instead, I find it a good idea to download a right <code>.deb</code> file from the <a href="http://www.debian.org/distrib/packages">Debian Packages Repository</a> and pick out the <code>.so</code> files.</p>
<hr/><p>Related posts:<ol>
<li><a href='http://en.chys.info/2010/12/concatenate-pdf-files-in-linux/' rel='bookmark' title='Concatenate PDF files in Linux'>Concatenate PDF files in Linux</a></li>
</ol></p>]]></content:encoded>
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		<item>
		<title>liblzmadec sucks</title>
		<link>http://en.chys.info/2009/05/liblzmadec-sucks/</link>
		<comments>http://en.chys.info/2009/05/liblzmadec-sucks/#comments</comments>
		<pubDate>Fri, 01 May 2009 18:38:02 +0000</pubDate>
		<dc:creator>chys</dc:creator>
				<category><![CDATA[Uncategorized]]></category>
		<category><![CDATA[compression]]></category>
		<category><![CDATA[dev]]></category>

		<guid isPermaLink="false">http://en.chys.info/?p=485</guid>
		<description><![CDATA[Both the executable lzma and the library liblzmadec are included in the package lzma-utils (in Gentoo). If I compress a file a.txt like this: lzma a.txt then liblzmadec can decompress a.txt.lzma perfectly. However, if I compress it like this: lzma < a.txt > a.txt.lzma Then liblzmadec fails. LZMA is a compression algorithm whose application rate [...]<hr/>
Related posts:<ol>
<li><a href='http://en.chys.info/2009/04/logrotating-emergelog/' rel='bookmark' title='[Gentoo] Logrotating emerge.log'>[Gentoo] Logrotating emerge.log</a></li>
</ol>]]></description>
			<content:encoded><![CDATA[<p>Both the executable <code>lzma</code> and the library <code>liblzmadec</code> are included in the package <code>lzma-utils</code> (in Gentoo).</p>
<p>If I compress a file <code>a.txt</code> like this:</p>
<blockquote><p><code>lzma a.txt</code></p></blockquote>
<p>then <code>liblzmadec</code> can decompress <code>a.txt.lzma</code> perfectly.</p>
<p>However, if I compress it like this:</p>
<blockquote><p><code>lzma < a.txt > a.txt.lzma</code></p></blockquote>
<p>Then <code>liblzmadec</code> fails.</p>
<hr/>
<p>LZMA is a compression algorithm whose application rate has been rapidly growing in the past year. In most cases, it has significantly better compression ratio compressed to <code>bzip2</code> and <code>gzip</code>, and decompresses significantly faster. However, its compression process is extremely slow (probably 10 times longer the time than <code>bzip2</code>).</p>
<p>One of the algorithms supported by <code><a href="http://www.7-zip.org/">7zip</a></code> is LZMA. In Linux we usually use <a href="http://tukaani.org/lzma/">LZMA Utils</a> instead.</p>
<p>GNU provided the tarball of some versions of <code>coreutils</code> in LZMA (in addition to the traditional GZIP), although they have recently switched to <code><a href="http://tukaani.org/xz/">xz</a></code>.</p>
<hr/><p>Related posts:<ol>
<li><a href='http://en.chys.info/2009/04/logrotating-emergelog/' rel='bookmark' title='[Gentoo] Logrotating emerge.log'>[Gentoo] Logrotating emerge.log</a></li>
</ol></p>]]></content:encoded>
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