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+---
+layout: page
+author: Domenico Votta
+category-page: advanced
+category-title: Advanced commands
+tags: compare sorted files
+title: comm
+---
+The <code>comm</code>  is a command that compares two sorted files line by line and writes the output: the lines that are in common and the lines that are unique. <br>
+
+Here we have two files named <code>example1.txt</code> and
+<code>example2.txt</code> that contain 5 elements, to test this command:<br>
+
+<code>example1.txt</code>
+{% highlight bash linenos %}
+Icecream
+Chocolate
+Cake
+Candy
+Biscuit
+{% endhighlight %}
+
+<code>example2.txt</code>
+{% highlight bash linenos %}
+Bread
+Chocolate
+Tomato
+Candy
+Pizza
+{% endhighlight %}
+
+The syntax command is:
+<pre>comm [flag][file1] [file2]</pre>
+
+<pre>
+comm example1.txt example2.txt
+Icecream
+    Chocolate
+Cake
+  Tomato
+    Candy
+Biscuit
+  Pizza
+</pre>
+
+<p>The elements of the first file doesn't have the tab.</p>
+<p>The elements of the second file have one tab.</p>
+<p>The elements in common have two tabs.</p>
+
+<h2>Flags</h2>
+
+<ul>
+  <li> <b>-1</b>: supress column 1</li>
+  <li> <b>-2</b>: supress column 2</li>
+  <li> <b>-3</b>: supress column 3</li>
+
+</ul>