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Diff for: ‎README.md

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## Tips
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* [CLI tip 21: inplace file editing with GNU awk](https://learnbyexample.github.io/tips/cli-tip-21/)
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* [Python tip 21: sorting iterables based on a key](https://learnbyexample.github.io/tips/python-tip-21/)
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* [Vim tip 19: working with buffers](https://learnbyexample.github.io/tips/vim-tip-19/)
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* [CLI tip 20: expand and unexpand](https://learnbyexample.github.io/tips/cli-tip-20/)

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<link href="https://learnbyexample.github.io/atom.xml" rel="self" type="application/atom+xml"/>
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<link href="https://learnbyexample.github.io"/>
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<generator uri="https://www.getzola.org/">Zola</generator>
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<updated>2023-01-02T00:00:00+00:00</updated>
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<updated>2023-01-04T00:00:00+00:00</updated>
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<id>https://learnbyexample.github.io/atom.xml</id>
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<entry xml:lang="en">
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<title>CLI tip 21: inplace file editing with GNU awk</title>
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<published>2023-01-04T00:00:00+00:00</published>
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<updated>2023-01-04T00:00:00+00:00</updated>
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<link rel="alternate" href="https://learnbyexample.github.io/tips/cli-tip-21/" type="text/html"/>
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<id>https://learnbyexample.github.io/tips/cli-tip-21/</id>
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<content type="html">&lt;p&gt;You can use the &lt;code&gt;-i&lt;&#x2F;code&gt; option with &lt;code&gt;GNU awk&lt;&#x2F;code&gt; to load libraries. The &lt;code&gt;inplace&lt;&#x2F;code&gt; library comes by default with the &lt;code&gt;GNU awk&lt;&#x2F;code&gt; installation. Thus, you can use &lt;code&gt;-i inplace&lt;&#x2F;code&gt; to modify the original input itself. Make sure to test that the code is working as intended before using this option.&lt;&#x2F;p&gt;
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&lt;pre data-lang=&quot;ruby&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-ruby &quot;&gt;&lt;code class=&quot;language-ruby&quot; data-lang=&quot;ruby&quot;&gt;&lt;span&gt;$ cat table.txt
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&lt;&#x2F;span&gt;&lt;span&gt;brown bread mat cake &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;42
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&lt;&#x2F;span&gt;&lt;span&gt;blue cake mug shirt &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;7
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&lt;&#x2F;span&gt;&lt;span&gt;yellow banana window shoes &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;3.14
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&lt;&#x2F;span&gt;&lt;span&gt;
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&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# retain only the first and third fields
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&lt;&#x2F;span&gt;&lt;span&gt;$ awk &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-&lt;&#x2F;span&gt;&lt;span&gt;i inplace &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;{print $1, $3}&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt; table.txt
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&lt;&#x2F;span&gt;&lt;span&gt;$ cat table.txt
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&lt;&#x2F;span&gt;&lt;span&gt;brown mat
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&lt;&#x2F;span&gt;&lt;span&gt;blue mug
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&lt;&#x2F;span&gt;&lt;span&gt;yellow window
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&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
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&lt;p&gt;You can provide a backup extension by setting the &lt;code&gt;inplace::suffix&lt;&#x2F;code&gt; special variable. For example, if the input file is &lt;code&gt;ip.txt&lt;&#x2F;code&gt; and &lt;code&gt;inplace::suffix=&#x27;.orig&#x27;&lt;&#x2F;code&gt; is used, the backup file will be named as &lt;code&gt;ip.txt.orig&lt;&#x2F;code&gt;.&lt;&#x2F;p&gt;
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&lt;pre data-lang=&quot;ruby&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-ruby &quot;&gt;&lt;code class=&quot;language-ruby&quot; data-lang=&quot;ruby&quot;&gt;&lt;span&gt;$ cat marks.txt
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&lt;&#x2F;span&gt;&lt;span&gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;Name Physics Maths
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&lt;&#x2F;span&gt;&lt;span&gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;Moe &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;76 82
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&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;Raj &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;56 64
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&lt;&#x2F;span&gt;&lt;span&gt;
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&lt;&#x2F;span&gt;&lt;span&gt;$ awk &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-&lt;&#x2F;span&gt;&lt;span&gt;i inplace &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-&lt;&#x2F;span&gt;&lt;span&gt;v inplace::suffix=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;.bkp&amp;#39; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-&lt;&#x2F;span&gt;&lt;span&gt;v &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;OFS&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;{$1=$1} 1&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt; marks.txt
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&lt;&#x2F;span&gt;&lt;span&gt;$ cat marks.txt
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&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;Name&lt;&#x2F;span&gt;&lt;span&gt;,&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;Physics&lt;&#x2F;span&gt;&lt;span&gt;,&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;Maths
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&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;Moe&lt;&#x2F;span&gt;&lt;span&gt;,&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;76&lt;&#x2F;span&gt;&lt;span&gt;,&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;82
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&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;Raj&lt;&#x2F;span&gt;&lt;span&gt;,&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;56&lt;&#x2F;span&gt;&lt;span&gt;,&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;64
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&lt;&#x2F;span&gt;&lt;span&gt;
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&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# original file is preserved in &amp;#39;marks.txt.bkp&amp;#39;
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&lt;&#x2F;span&gt;&lt;span&gt;$ cat marks.txt.bkp
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&lt;&#x2F;span&gt;&lt;span&gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;Name Physics Maths
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&lt;&#x2F;span&gt;&lt;span&gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;Moe &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;76 82
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&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;Raj &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;56 64
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&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
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&lt;p&gt;&lt;img src=&quot;&#x2F;images&#x2F;info.svg&quot; alt=&quot;info&quot; &#x2F;&gt; Earlier versions of &lt;code&gt;GNU awk&lt;&#x2F;code&gt; used &lt;code&gt;INPLACE_SUFFIX&lt;&#x2F;code&gt; variable instead of &lt;code&gt;inplace::suffix&lt;&#x2F;code&gt;. Also, you can use &lt;code&gt;inplace::enable&lt;&#x2F;code&gt; variable to dynamically control whether files should be inplaced or not. See &lt;a href=&quot;https:&#x2F;&#x2F;www.gnu.org&#x2F;software&#x2F;gawk&#x2F;manual&#x2F;gawk.html#Extension-Sample-Inplace&quot;&gt;gawk manual: Enabling In-Place File Editing&lt;&#x2F;a&gt; for more details.&lt;&#x2F;p&gt;
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&lt;p&gt;&lt;strong&gt;Video demo&lt;&#x2F;strong&gt;:&lt;&#x2F;p&gt;
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&lt;p align=&quot;center&quot;&gt;&lt;iframe width=&quot;560&quot; height=&quot;315&quot; loading=&quot;lazy&quot; src=&quot;https:&#x2F;&#x2F;www.youtube.com&#x2F;embed&#x2F;yfO-HVTBoSI&quot; title=&quot;YouTube video player&quot; frameborder=&quot;0&quot; allow=&quot;accelerometer; clipboard-write; encrypted-media; gyroscope; picture-in-picture&quot; allowfullscreen&gt;&lt;&#x2F;iframe&gt;&lt;&#x2F;p&gt;
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&lt;br&gt;
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&lt;p&gt;&lt;img src=&quot;&#x2F;images&#x2F;info.svg&quot; alt=&quot;info&quot; &#x2F;&gt; See my &lt;a href=&quot;https:&#x2F;&#x2F;github.com&#x2F;learnbyexample&#x2F;learn_gnuawk&quot;&gt;GNU AWK&lt;&#x2F;a&gt; ebook if you are interested in learning about the &lt;code&gt;GNU awk&lt;&#x2F;code&gt; command in more detail.&lt;&#x2F;p&gt;
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</content>
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</entry>
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<entry xml:lang="en">
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<title>2022: year in perspective</title>
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<published>2022-12-30T00:00:00+00:00</published>

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</url>
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<lastmod>2023-01-04</lastmod>
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</url>
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<url>
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<loc>https://learnbyexample.github.io/tips/cli-tip-21/</loc>
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<lastmod>2023-01-04</lastmod>
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</span><span style=color:#7f8989;># remaining space is left as is
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</span><span>$ </span><span style=color:#b39f04;>printf </span><span style=color:#d07711;>' a b c\n' </span><span style=color:#72ab00;>|</span><span> unexpand </span><span style=color:#72ab00;>|</span><span> cat </span><span style=color:#72ab00;>-</span><span style=color:#5597d6;>T
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</span></code></pre><p><strong>Video demo</strong>:<p align=center><iframe allow="accelerometer; clipboard-write; encrypted-media; gyroscope; picture-in-picture" title="YouTube video player" allowfullscreen frameborder=0 height=315 loading=lazy src=https://www.youtube.com/embed/tsJCtE6oZDs width=560></iframe></p><br><p><img alt=info src=/images/info.svg> See <a href=https://learnbyexample.github.io/cli_text_processing_coreutils/expand-unexpand.html>expand and unexpand</a> chapter my <a href=https://github.com/learnbyexample/cli_text_processing_coreutils>Command line text processing with GNU Coreutils</a> ebook for more examples, options, etc.</div><div class=post-footer><div class=post-tags><a href=https://learnbyexample.github.io/tags/linux/>#linux</a><a href=https://learnbyexample.github.io/tags/command-line/>#command-line</a><a href=https://learnbyexample.github.io/tags/tip/>#tip</a></div><hr color=#e6e6e6><div class=post-nav><p><a class=next href=https://learnbyexample.github.io/tips/cli-tip-19/>CLI tip 19: extended globs →</a><br></div><hr color=#e6e6e6><p>📰 Use <a href=https://learnbyexample.github.io/atom.xml>this link</a> for the Atom feed. <br> ✅ Follow me on <a href=https://twitter.com/learn_byexample>Twitter</a>, <a href=https://github.com/learnbyexample>GitHub</a> and <a href=https://www.youtube.com/c/learnbyexample42>Youtube</a> for interesting tech nuggets. <br> 📧 Subscribe to <a href=https://learnbyexample.gumroad.com/l/learnbyexample-weekly>learnbyexample weekly</a> for programming resources, tips, tools, free ebooks and more (free newsletter, delivered every Friday).<hr color=#e6e6e6></div></article></div></main></div><script src=https://learnbyexample.github.io/even.js></script>
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</span></code></pre><p><strong>Video demo</strong>:<p align=center><iframe allow="accelerometer; clipboard-write; encrypted-media; gyroscope; picture-in-picture" title="YouTube video player" allowfullscreen frameborder=0 height=315 loading=lazy src=https://www.youtube.com/embed/tsJCtE6oZDs width=560></iframe></p><br><p><img alt=info src=/images/info.svg> See <a href=https://learnbyexample.github.io/cli_text_processing_coreutils/expand-unexpand.html>expand and unexpand</a> chapter my <a href=https://github.com/learnbyexample/cli_text_processing_coreutils>Command line text processing with GNU Coreutils</a> ebook for more examples, options, etc.</div><div class=post-footer><div class=post-tags><a href=https://learnbyexample.github.io/tags/linux/>#linux</a><a href=https://learnbyexample.github.io/tags/command-line/>#command-line</a><a href=https://learnbyexample.github.io/tags/tip/>#tip</a></div><hr color=#e6e6e6><div class=post-nav><p><a class=previous href=https://learnbyexample.github.io/tips/cli-tip-21/>← CLI tip 21: inplace file editing with GNU awk</a><br><p><a class=next href=https://learnbyexample.github.io/tips/cli-tip-19/>CLI tip 19: extended globs →</a><br></div><hr color=#e6e6e6><p>📰 Use <a href=https://learnbyexample.github.io/atom.xml>this link</a> for the Atom feed. <br> ✅ Follow me on <a href=https://twitter.com/learn_byexample>Twitter</a>, <a href=https://github.com/learnbyexample>GitHub</a> and <a href=https://www.youtube.com/c/learnbyexample42>Youtube</a> for interesting tech nuggets. <br> 📧 Subscribe to <a href=https://learnbyexample.gumroad.com/l/learnbyexample-weekly>learnbyexample weekly</a> for programming resources, tips, tools, free ebooks and more (free newsletter, delivered every Friday).<hr color=#e6e6e6></div></article></div></main></div><script src=https://learnbyexample.github.io/even.js></script>

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