77 lines
1.5 KiB
HTML
77 lines
1.5 KiB
HTML
---
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layout: page
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author: Domenico Votta
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category-page: advanced
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category-title: Advanced commands
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tags: number lines count
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title: nl
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previous-page: pages/cmd/advanced/head-tail.html
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next-page: pages/cmd/advanced/paste.html
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---
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<code>nl</code> is a command that allows you to number the lines.
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Through some flags you can decide how to filter this command.<br>
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We have a file named <code>example.txt</code> that contains 5 elements, to test this command:
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{% highlight bash %}
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Car
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Computer
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Robot
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Smartphone
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Videogame
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{% endhighlight %}
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The syntax is:
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<pre> nl [flags][file] </pre>
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<pre>
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nl example.txt
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1 Car
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2 Computer
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3 Robot
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4 Smartphone
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5 Videogame
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</pre>
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As you can see, the command has numbered the lines.
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<h2>Flags</h2>
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<ul>
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<li> <b>-b (regex)</b>: Specify the lines to be numbered
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<pre>
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nl -b p^[cv] example.txt
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1 Car
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2 Computer
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3 Videogame
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Robot
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Smartphone
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</pre>
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The part after the flag is used to number only the lines that start with c and v.
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</li>
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<li> -b<b>n</b>: The flag n goes with b, doesn't number any lines
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<pre>
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nl -bn example.txt
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Car
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Computer
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Videogame
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Robot
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Smartphone
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</pre>
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</li>
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<li> <b>-s</b>: Usually nl separes the number of the line from the text with a tab, with -s
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flag you can choose another separator, in this example we will use "=".
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<pre>
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nl -s= example.txt
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1=Car
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2=Computer
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3=Videogame
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4=Robot
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5=Smartphone
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</pre>
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</li>
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</ul>
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