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<!doctypehtml><html class="sidebar-visible no-js light"lang=en><head><meta charset=UTF-8><title>Introduction - CLI text processing with GNU Coreutils</title><meta content="text/html; charset=utf-8"http-equiv=Content-Type><meta content="Example based guide for specialized text processing with GNU Coreutils"name=description><meta content=width=device-width,initial-scale=1 name=viewport><meta content=#ffffff name=theme-color><meta content="CLI text processing with GNU Coreutils"property=og:title><meta content=website property=og:type><meta content="Example based guide for specialized text processing with GNU Coreutils"property=og:description><meta content=https://learnbyexample.github.io/cli_text_processing_coreutils/ property=og:url><meta content=https://raw.githubusercontent.com/learnbyexample/cli_text_processing_coreutils/main/images/cli_coreutils_ls.png property=og:image><meta content=1280 property=og:image:width><meta content=720 property=og:image:height><meta content=summary_large_image property=twitter:card><meta content=@learn_byexample property=twitter:site><link href=favicon.svg rel=icon><link rel="shortcut icon"href=favicon.png><link href=css/variables.css rel=stylesheet><link href=css/general.css rel=stylesheet><link href=css/chrome.css rel=stylesheet><link href=FontAwesome/css/font-awesome.css rel=stylesheet><link href=fonts/fonts.css rel=stylesheet><link href=highlight.css rel=stylesheet><link href=tomorrow-night.css rel=stylesheet><link href=ayu-highlight.css rel=stylesheet><link href=style.css rel=stylesheet><body><script>var path_to_root = "";
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html.classList.add("sidebar-" + sidebar);</script><nav aria-label="Table of contents"class=sidebar id=sidebar><div class=sidebar-scrollbox><ol class=chapter><li class="chapter-item expanded affix"><a href=cover.html>Cover</a><li class="chapter-item expanded affix"><a href=buy.html>Buy PDF/EPUB versions</a><li class="chapter-item expanded affix"><a href=preface.html>Preface</a><li class="chapter-item expanded"><a class=active href=introduction.html><strong aria-hidden=true>1.</strong> Introduction</a><li class="chapter-item expanded"><a href=cat-tac.html><strong aria-hidden=true>2.</strong> cat and tac</a><li class="chapter-item expanded"><a href=head-tail.html><strong aria-hidden=true>3.</strong> head and tail</a><li class="chapter-item expanded"><a href=tr.html><strong aria-hidden=true>4.</strong> tr</a><li class="chapter-item expanded"><a href=cut.html><strong aria-hidden=true>5.</strong> cut</a><li class="chapter-item expanded"><a href=seq.html><strong aria-hidden=true>6.</strong> seq</a><li class="chapter-item expanded"><a href=shuf.html><strong aria-hidden=true>7.</strong> shuf</a><li class="chapter-item expanded"><a href=paste.html><strong aria-hidden=true>8.</strong> paste</a><li class="chapter-item expanded"><a href=pr.html><strong aria-hidden=true>9.</strong> pr</a><li class="chapter-item expanded"><a href=fold-fmt.html><strong aria-hidden=true>10.</strong> fold and fmt</a><li class="chapter-item expanded"><a href=sort.html><strong aria-hidden=true>11.</strong> sort</a><li class="chapter-item expanded"><a href=uniq.html><strong aria-hidden=true>12.</strong> uniq</a><li class="chapter-item expanded"><a href=comm.html><strong aria-hidden=true>13.</strong> comm</a><li class="chapter-item expanded"><a href=join.html><strong aria-hidden=true>14.</strong> join</a><li class="chapter-item expanded"><a href=nl.html><strong aria-hidden=true>15.</strong> nl</a><li class="chapter-item expanded"><a href=wc.html><strong aria-hidden=true>16.</strong> wc</a><li class="chapter-item expanded"><a href=split.html><strong aria-hidden=true>17.</strong> split</a><li class="chapter-item expanded"><a href=csplit.html><strong aria-hidden=true>18.</strong> csplit</a><li class="chapter-item expanded"><a href=expand-unexpand.html><strong aria-hidden=true>19.</strong> expand and unexpand</a><li class="chapter-item expanded"><a href=basename-dirname.html><strong aria-hidden=true>20.</strong> basename and dirname</a><li class="chapter-item expanded affix"><a href=what_next.html>What next?</a><li class="chapter-item expanded affix"><a href=Exercise_solutions.html>Exercise solutions</a></li><br><hr><li class="chapter-item expanded"><i class="fa fa-github"id=git-repository-button></i><a href=https://github.com/learnbyexample/cli_text_processing_coreutils> Source code</a><li class="chapter-item expanded"><i class="fa fa-home"id=home-button></i><a href=https://learnbyexample.github.io/> My Blog</a><li class="chapter-item expanded"><i class="fa fa-book"id=book-button></i><a href=https://learnbyexample.github.io/books/> My Books</a><li class="chapter-item expanded"><i class="fa fa-envelope"id=mail-button></i><a href=https://learnbyexample.gumroad.com/l/learnbyexample-weekly> learnbyexample weekly</a><li class="chapter-item expanded"><i class="fa fa-twitter"id=twitter-button></i><a href=https://twitter.com/learn_byexample> Twitter</a></ol></div><div class=sidebar-resize-handle id=sidebar-resize-handle></div></nav><div class=page-wrapper id=page-wrapper><div class=page><div id=menu-bar-hover-placeholder></div><div class="menu-bar sticky bordered"id=menu-bar><div class=left-buttons><button aria-label="Toggle Table of Contents"title="Toggle Table of Contents"aria-controls=sidebar class=icon-button id=sidebar-toggle type=button><i class="fa fa-bars"></i></button><button aria-label="Change theme"title="Change theme"aria-controls=theme-list aria-expanded=false aria-haspopup=true class=icon-button id=theme-toggle type=button><i class="fa fa-paint-brush"></i></button><ul aria-label=Themes class=theme-popup id=theme-list role=menu><li role=none><button class=theme id=light role=menuitem>Light (default)</button><li role=none><button class=theme id=rust role=menuitem>Rust</button><li role=none><button class=theme id=coal role=menuitem>Coal</button><li role=none><button class=theme id=navy role=menuitem>Navy</button><li role=none><button class=theme id=ayu role=menuitem>Ayu</button></ul><button aria-label="Toggle Searchbar"title="Search. (Shortkey: s)"aria-controls=searchbar aria-expanded=false aria-keyshortcuts=S class=icon-button id=search-toggle type=button><i class="fa fa-search"></i></button></div><h1 class=menu-title>CLI text processing with GNU Coreutils</h1><div class=right-buttons><a aria-label=Blog href=https://learnbyexample.github.io title=Blog> <i class="fa fa-home"id=home-button></i> </a><a aria-label=Twitter href=https://twitter.com/learn_byexample title=Twitter> <i class="fa fa-twitter"id=twitter-button></i> </a><a aria-label="Git repository"title="Git repository"href=https://github.com/learnbyexample/cli_text_processing_coreutils> <i class="fa fa-github"id=git-repository-button></i> </a></div></div><div class=hidden id=search-wrapper><form class=searchbar-outer id=searchbar-outer><input placeholder="Search this book ..."aria-controls=searchresults-outer aria-describedby=searchresults-header id=searchbar name=searchbar type=search></form><div class="searchresults-outer hidden"id=searchresults-outer><div class=searchresults-header id=searchresults-header></div><ul id=searchresults></ul></div></div><script>document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
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});</script><div class=content id=content><main><div class=sidetoc><nav class=pagetoc></nav></div><h1 id=introduction><a class=header href=#introduction>Introduction</a></h1><p>I've been using Linux since 2007, but it took me ten more years to <em>really</em> explore coreutils when I wrote tutorials for the <a href=https://github.com/learnbyexample/Command-line-text-processing>Command Line Text Processing</a> repository.<p>Any beginner learning Linux command line tools would come across the <code>cat</code> command within the first week. Sooner or later, they'll come to know popular text processing tools like <code>grep</code>, <code>head</code>, <code>tail</code>, <code>tr</code>, <code>sort</code>, etc. If you were like me, you'd come across <code>sed</code> and <code>awk</code>, shudder at their complexity and prefer to use a scripting language like Perl and text editors like Vim instead (don't worry, I've already corrected that mistake).<p>Knowing power tools like <code>grep</code>, <code>sed</code> and <code>awk</code> can help solve most of your text processing needs. So, why would you want to learn text processing tools from the coreutils package? The biggest motivation would be faster execution since these tools are optimized for the use cases they solve. And there's always the advantage of not having to write code (and test that solution) if there's an existing tool to solve the problem.<p>This book will teach you more than twenty of such specialized text processing tools provided by the <code>GNU coreutils</code> package. Plenty of examples and exercise are provided to make it easier to understand a particular tool and its various features.<p>Writing a book always has a few pleasant surprises for me. For this one, it was discovering a <code>sort</code> option for calendar months, regular expressions in the <code>tac</code> and <code>nl</code> commands, etc.<h2 id=installation><a class=header href=#installation>Installation</a></h2><p>On a GNU/Linux based OS, you are most likely to already have GNU coreutils installed. This book covers the <strong>version 9.1</strong> of the coreutils package. To install a newer/particular version, see the <a href=https://www.gnu.org/software/coreutils/#download>coreutils download</a> section for details.<p>If you are not using a Linux distribution, you may be able to access coreutils using these options:<ul><li><a href=https://en.wikipedia.org/wiki/Windows_Subsystem_for_Linux>Windows Subsystem for Linux</a> — compatibility layer for running Linux binary executables natively on Windows<li><a href=https://brew.sh/>brew</a> — Package Manager for macOS (or Linux)</ul><h2 id=documentation><a class=header href=#documentation>Documentation</a></h2><p>It is always a good idea to know where to find the documentation. From the command line, you can use the <code>man</code> and <code>info</code> commands for brief manuals and full documentation respectively. I prefer using the <a href=https://www.gnu.org/software/coreutils/manual/coreutils.html>online GNU coreutils manual</a> which feels much easier to use and navigate.<p>See also:<ul><li><a href=https://lists.gnu.org/archive/cgi-bin/namazu.cgi?query=released&submit=Search%21&idxname=coreutils-announce&max=20&result=normal&sort=date%3Alate>Release notes</a> — overview of changes and bug fixes between versions<li><a href=https://lists.gnu.org/archive/html/bug-coreutils/>Bug list</a><li><a href=https://www.gnu.org/software/coreutils/manual/html_node/Common-options.html>Common options</a><li><a href=https://www.gnu.org/software/coreutils/faq/>FAQ</a><li><a href=https://www.pixelbeat.org/docs/coreutils-gotchas.html>Gotchas</a></ul></main><nav aria-label="Page navigation"class=nav-wrapper><a aria-label="Previous chapter"class="mobile-nav-chapters previous"title="Previous chapter"aria-keyshortcuts=Left href=preface.html rel=prev> <i class="fa fa-angle-left"></i> </a><a aria-label="Next chapter"class="mobile-nav-chapters next"title="Next chapter"aria-keyshortcuts=Right href=cat-tac.html rel=next> <i class="fa fa-angle-right"></i> </a><div style="clear: both"></div></nav></div></div><nav aria-label="Page navigation"class=nav-wide-wrapper><a aria-label="Previous chapter"class="nav-chapters previous"title="Previous chapter"aria-keyshortcuts=Left href=preface.html rel=prev> <i class="fa fa-angle-left"></i> </a><a aria-label="Next chapter"class="nav-chapters next"title="Next chapter"aria-keyshortcuts=Right href=cat-tac.html rel=next> <i class="fa fa-angle-right"></i> </a></nav></div><script>window.playground_copyable = true;</script><script charset=utf-8 src=elasticlunr.min.js></script><script charset=utf-8 src=mark.min.js></script><script charset=utf-8 src=searcher.js></script><script charset=utf-8 src=clipboard.min.js></script><script charset=utf-8 src=highlight.js></script><script charset=utf-8 src=book.js></script><script src=sidebar.js></script>