--- layout: page author: Domenico Votta category-page: advanced category-title: Advanced commands tags: search for occurences title: grep ---

The grep is a command that permits to search occurences of a keyword or more in a file or more. Through some flags you can decide the search criteria. The command grep is case sensitive (robot is different from Robot), but we will see how to ignore it

Here we have two files named example1.txt and example2.txt that contain 5 elements, to test this command: example1.txt {% highlight bash linenos %} Car Computer Robot Smartphone Videogame {% endhighlight %} example2.txt {% highlight bash linenos %} Apple Computer Robot Microsoft Huawei {% endhighlight %} The syntax command is:
grep [flag] [keyword] [file]
You can put different flags together to refine the search. {% highlight ruby linenos %} grep Robot example1.txt example2.txt (if you write robot you won't have the correspondence.) example1.txt: Robot example2.txt: Robot {% endhighlight %}

Your output will be this because grep found the keyword Robot in both files

Flags

Here a list that contains the main flags of these command: