43 lines
1.1 KiB
HTML
43 lines
1.1 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: pipes redirect output input
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title: Pipes
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previous-page: pages/cmd/advanced/paste.html
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next-page: pages/cmd/advanced/tr.html
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---
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The <code>pipes</code>, which in the shell are represented with the symbol | ,
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are used to join two commands on the terminal, taking the output of the first
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command and using it as input of the second.<br>
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It is common to see the commands <code>grep</code> and <code>ps</code> together,
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an example below.<br>
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Example: lists all processes with your username
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<pre>
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ps aux | grep user
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</pre>
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Example: count the lines of a file, using the
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<a href="{{ site.baseurl }}/pages/cmd/advanced/nl.html">nl</a> command
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<pre>
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cat example1.txt | nl
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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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Example: passing expressions to <a href="{{ site.baseurl }}/pages/cmd/advanced/bc.html">bc</a>
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to do calculations
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<pre>
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echo "(12 / 2 - 3) * 3 + 1.5" | bc
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10.5
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</pre>
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You can use the commands that you learned and put them together, always
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respecting the logic of the command.
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