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‫Now grep, this is a command.

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‫Well, I'll tell you that grep stands for globally, search for a regular expression and then print

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‫it out.

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‫So that's why we say grip.

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‫But the grab command basically searches a file for a particular pattern of characters.

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‫And then it'll display of lines that contain that pattern.

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‫The tech search pattern is called a regular expression.

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‫So when it finds a match, it prints the line with a result.

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‫The grep command is handy when searching through very large log files, for instance.

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‫The Dash I parameters used to perform case insensitive searches.

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‫You can use regular expressions with Dash E parameters.

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‫Dash, our parameters can be used to read all files under each directory.

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‫Recursively.

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‫And then finally, the Dash V parameter, we use that when we want to select none matching lines.

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‫All right, so let's give it a shot.

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‫Let's go to Carly.

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‫Let's read the content of the slash Etsy password file.

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‫So this is a plain text file that contains a list of this system's account.

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‫Giving for each account some useful information like User ID, Group, I.D., Home Directory, Shell

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‫and so much more.

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‫Of course, we could search for a particular pattern in this file, so let's run grep Cowley slash ETSI

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‫slash police S.W.2d.

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‫And here, as you can see, it, filtered the result containing Kelly.

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‫So why don't we use a regular expression with the Dash E parameter?

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‫So Linux regular expressions are special characters which help search data and matching complex patterns.

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‫So if we had the carrot symbol to the beginning of a word, it'll display the pattern to start with

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‫Callie.

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‫Now, to do a case insensitive search, we can always add the Dash II parameter.

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‫And will capitalize the first letter of Kelly so that we can see the result.

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‫Now, as you can see, the result did not change.

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‫It shows the patterns that start with Carly, regardless of upper or lower case.

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‫All right, so now let's perform a recursive search.

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‫So we can search for open VPN under these last user folder recursively.

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‫We can also see the full path of the matched pattern.

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‫Now, if you want to select non matching mines, you can just use the Dash V parameter.

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‫And it shows the patterns that do not start with Kelly.