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In this demonstration,

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we're going to return to the check storage script,

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and we're going to go over a few things.

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Instead of me typing everything out,

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I just went ahead and typed it for us.

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But we're just going to go over

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conditional branches for an if else statement.

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Again, we want the script to be able

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to present information based

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off certain conditions of the system.

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So if we look here, I'll scroll

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down just a little bit to get to the part

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that I added.

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Now, if you look at line 13,

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I added our first conditional branch.

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What that statement is merely saying is,

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if we run the check per variable,

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that run earlier,

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that's the command that we created.

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If the value is greater than 95

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but less than 100% full,

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we want to print the echo statement alert.

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This partition,

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which is going to be /dev/sda1, is 25%.

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that's what it was in the last lesson, full

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and we recommend immediate action.

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But just think about that though.

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The fact that it's currently

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at 25% means that this wouldn't be triggered.

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So the value of that number has to

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actually be greater

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than 95

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in less than 100.

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So if it's 95, it won't pass the test.

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So anything 95 and below,

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this alert will not be triggered, but anything 96

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and above will be, long as it's less than 100.

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So again, it's going to go through

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each and every one of these conditional statements,

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and it's going to check if,

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then it's going to run the variable,

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it's going to run the command,

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and it's going to compare those values.

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And if the statement is true

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'cause remember both of the statements have to be true.

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It has to be greater than 95,

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but also less than 100.

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And then again, it's going to go through the next one.

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Else if.

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Next thing it's going to do, it's going to check to see

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if it's greater than 50, but less than 95.

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And it's going to print out a different command.

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It's going to print out caution,

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consider freeing up some space.

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Again, this is a more practical script

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because it gives us advice

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on what to do when certain conditions are met.

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So again, it's going to check to see

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if the particular partition is greater

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than 50 and also less than 95.

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The next FL statement, it's going to check to see

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if the partition is less than 50%.

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And if it is we're going to print out,

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hey, no action is needed

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because we determined anything less than 50%

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is good to go.

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Now, if it goes through this entire set

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of conditional branches and none

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of the conditions are met,

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we're going to print out that

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we encountered an error because it has

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to meet at least one of them.

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If not, then there's an issue.

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Remember that the >&2 if we

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have those together, that means that

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we're going to print that information

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out on the terminal for the user to read.

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And it's going to print out an error

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and it's going to give us its status code

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because that's what that particular variable,

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the question mark refers to.

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And then we're going to exit out.

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And the fi just means we're finished with that set

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of conditional statements that started

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with the if.

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Now let's go ahead and run that command

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and check storage.

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Now let's view this report.

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Now we see this time rather than just give us

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the information, we're also giving

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us the required action necessary.

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It's at 25% and no action is needed,

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because if you refer back to our script,

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anything that's less than 50 that's

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what's going to be executed.

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Next we're going to go through and actually modify

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this script to incorporate more than one drive

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because realistically we want to know the value

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of multiple sets of drives

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usually all versus just one.

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So we're going to modify this script

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to use everything

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that's associated in the /dev directory,

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which points to the hard disk

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that's associated to our system.

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So what we need to do is modify this partition

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variable that we established earlier.

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So we're going to make this into a command

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and this command is going to go through

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and it's going to check our /dev folder

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and everything that has the /dev associated

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with it. That's where we're going to reference.

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Let's do that really quick.

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So we're going to use the variable.

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So that means that we're going to get that information.

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Whatever the value that is returned,

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that's what we want to print out.

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Okay? So we know what that command means.

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We're going to take

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everything from the first row

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And it has to look like this /dev

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and that's going to be what's returned to us.

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So if we just use this command really quick

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in our shell, we'll see what we return to us.

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So again, we use a disk free human

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readable variable.

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We're going to pull out everything that's

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in the first row,

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and it must be presented in the /dev format.

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Okay? So once we run the script

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we should get the values for those two hard disks.

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'Cause that's what I have associated

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under /dev in this particular device.

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So we should get more than one value.

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We should also include the map or CentOS root.

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Okay? So now we know what that command means.

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Now, we need to do a loop.

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We need to actually check the first one

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the second one, third, etc.

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For this example, we only have two

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but we're going to modify this

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so that it's going to check multiple.

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And then it's going to convert that value

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that's returned in the partition variable

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into an array.

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And an array is nothing more

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than a set of similar values typically.

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And for this example

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the similar values are going to be the hard drives.

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So we're going to go through

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and loop through two different hard drives.

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Okay, let's go ahead and modify this.

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For this one do the four loop.

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The i represents the individual array that's

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selected once we're going through processing

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each one of these commands.

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We're going to do N

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partition.

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And this means all, every single one of them

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that's what the asterisk stands for.

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Okay?

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This is going to begin the four loop.

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And again, the i variable is the iterator.

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The part variable is being referenced

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as an array with the asterisk, indicating all values

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in that array.

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For every index in the array,

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the script will execute what follows after.

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Okay? So for that, we want to use the DO.

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And the DO statement begins the code

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that the loop will execute on each iteration.

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The i is going to represent /dev map or CentOS root

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and also /dev/sda1.

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Now let's go ahead and go to the bottom

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after the finish.

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Everyone type done.

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That's going to indicate the end of that loop.

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So before we continue,

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we have to modify every instance of

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the partition variable.

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Remember having return it to the i okay.

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A partition here.

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Need to reference that index,

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not the entire array.

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Okay.

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Make sure there's no more associations

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with the partition itself, but the index

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of that partition looks like we're good to go.

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Save.

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Alright.

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Now let's go ahead and rerun this command

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and see what we get.

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Okay.

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Perfect.

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Looks like we went through.

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We checked to see the information

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and the CentOS root is over 95% full

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so it requires immediate action.

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For the sda1 is only 25% full

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so no action is needed.

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Okay. We see that when it checked

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multiple different hard disks,

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that we were able to trigger different

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conditional branches.

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So we see that the CentOS root,

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was above 95% so it gave us

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the indication that immediate action was required.

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And we see that our sda1 was still good to go

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with less than 50% so no action was required.

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So just a recap.

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We went over how to create a script and modify it

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so it's able to iterate through

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multiple different

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hard disks to give us more practical information

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for managing our systems.

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Thank you for sticking with this walkthrough

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and I'll see you in the next lesson.