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So in the previous video, we learned how to utilize the STAT module and the way

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we learned how to use this module was via AnsibleDoc.

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Now in this particular video, what I want to highlight to you is yet another

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module.

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This time called "line and fail" and once again we're going to be utilizing Ans

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ibleDoc to learn how to actually use this.

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Now one thing I will say here, you will recall in previous videos or rather

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previous skills, we happen to use the Genji 2 templating language

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and this allows us to effectively render an entire configuration file and then
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and this allows us to effectively render an entire configuration file and then

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we could use something like the copy module

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to copy those rendered configs over to the target machines.

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Now quite honestly when we happen to be making many many changes to a

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particular configuration, this is my preferred method.

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It is much more comprehensive, it gives us access to programmatic logic that

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type of thing, but it also can be quite time consuming

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and honestly it can be a little bit difficult depending on just how complex the

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configurations are.

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And quite honestly, sometimes all you have to do is to make a simple change
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And quite honestly, sometimes all you have to do is to make a simple change

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within a configuration file, perhaps maybe one line has to change

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or maybe a block of lines have to change that type of thing as opposed to

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really having to render an entire configuration altogether.

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So given the fact that we're now learning to explore AnsibleDoc, I thought this

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would be a good time to introduce this particular module, "line and fail".

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So with that said, let's go and check it out.

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So once again, if we just list what we actually have here within our AnsibleDoc

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, if I scroll on down, notice we have this one right here, "line and fail", and
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, if I scroll on down, notice we have this one right here, "line and fail", and

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it says here,

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this is going to allow us to manage lines in text files.

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So all I will do here is just grab this and copy here, press "Q" and I'll call

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the screen, and then I'll just say " AnsibleDoc" and then paste in the name of

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the module.

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So as per the description, what it says here is that this module is going to

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ensure that a particular line is in a file or replace a particular line and

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existing line that is.

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Notice the use case here, this is primarily useful when you want to change a

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single line in a file only.
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single line in a file only.

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So like I say, as opposed to rendering the entire configuration via Ginger2,

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this module can help us simplify that process.

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So let's scroll on down, and we can see all of the available options once again

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.

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Notice we have options such as "insert before", so the line is going to be

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inserted before the last match of the specified regular expressions.

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Once again, this is what we're going to be utilizing.

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So say for example, you have the option "insert before", pretty much what we're

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going to do is to make use of a regular expression to determine a particular

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pattern within the file,
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pattern within the file,

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and this particular option is going to insert whatever text you select or

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rather provide before the last match of that regex.

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So like I say, you can explore this at your leisure, we have many, many options

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here.

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Notice this one right here, we have the "equal sign" and the "path" option.

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This again tells us that this is a mandatory parameter, and pretty much this is

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going to allow us to select the file that we want to target.

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Notice this option here "state" as well, this is whether a line should be there

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or not, so we have the option to specify should the line be absent or should
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or not, so we have the option to specify should the line be absent or should

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the line be present.

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So if we want to remove a particular line, we can specify "absent" or if we

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want to ensure it's there or we can set it to "present".

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Notice we also have this other option here "redjxp" and it's via this

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particular parameter that we can provide the regular expression for the pattern

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matching.

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So let's go and check this out then.

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So what I'm going to do here is let me go into my blue box and all I will do is

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go into my temp directory and I'm just going to create a file called "names.txt
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go into my temp directory and I'm just going to create a file called "names.txt

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".

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So we go into insert mode, I will say "James", "Somonor", "John", "Knox", "K

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ieth", and if I just press "skate colon wq" to write and quit, here is the file

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right here.

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And what I want to do is I want to target this particular file and I'm going to

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remove a particular line from this file, in this case here, I'm going to remove

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my name "John".

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Now of course this could be applied to a complex configuration file, maybe it's

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a DNS mapping, whatever it may be, but in the interest of simplicity, I'm just

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highlighting the name of the file.
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I'm just highlighting the most simple case right here, so our basic text file.

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So what I'm going to do here is I'm going to create a playbook called "play5.y

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ml".

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Going to insert mode, have our three hyphens at the top, you know the drill.

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And we give it a name, "play5", "test the line in file module".

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Who am I going to target? Well I could target both devices if I so wish but in

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my case here, I'm just going to target the blue box and I will set "gather

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facts" to false to keep things in this display.

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And now I will define my tasks, so the name here, I'll just say "remove name

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from text file".
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from text file".

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Now what is the actual module I'm going to be using? It's going to be "answer

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able built in", "line in file".

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And we know the path parameter is "mandatory".

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So the path I want to target is going to be the temp directory and the file is

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going to be called "names.txt".

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Now what I want to do is I want to specify the states and I want something to

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be absent.

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Now what exactly do I want to be absent? What am I trying to match here? Well I

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can specify my Reg XP parameter.

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And all I'm going to do is to provide some regular expressions.
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And all I'm going to do is to provide some regular expressions.

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Now this here is not going to be a course on regular expressions.

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You can look online to see how we can actually format these things.

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So basically I have my carrot to denote my start anchor and my dollar sign to

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denote my end anchor.

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Pretty much all I'm doing is saying that I want to match the word "John"

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exactly.

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So quite simply the module is going to search for this particular pattern "John

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".

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And if it finds it it's going to remove it because the state should be absent.

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So let's try this out then. And also "answerable playbook", "play5.yml" and "t
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So let's try this out then. And also "answerable playbook", "play5.yml" and "t

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it" "enter".

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Give it a moment and now we have a change. So if we go to verify this, we go

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back to the blue box.

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Let's cat the names. Once again, look at this right here.

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"John" has actually been removed from the list of names.

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Similarly, let's say we wanted to add a particular line in a file.

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Let's go in to play5 once again. And I'll create a new task.

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And I'll just say "adding name to text file".

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What I'm going to use, I'm going to use the "answerable built-in" line and file

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module once again.

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The path will be targeting the same text file.
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The path will be targeting the same text file.

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Now I'm going to specify the line that I want to add. So let me add the name "

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La La" here.

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And if you look at the documentation, we also have this option to create.

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And all I will do is specify the value "yes".

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So if I just save this right here. And I read on the playbook, give it a moment

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.

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And check this out. Now we have made a change once again to the blue box.

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So let's cat the same file. Once again, we have successfully added "La La" to

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the list of names using the line in file module.

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So as you know, we have a lot of available modules within "answerable".
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So as you know, we have a lot of available modules within "answerable".

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We've just seen a few more within this particular skill.

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And remember the best place to find out about how to use these modules is

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directly via the documentation.

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And we can access that documentation directly on our terminal utilizing "answer

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able.com".