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(upbeat instrumental music)

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- [Instructor] Let's look at

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solving those challenges

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having to do with the greatest number,

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and largest number

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or things related to loadable modules.

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So the first question is,

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the greatest number of used by.

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So we look at lsmod,

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and remember it's that last column,

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that's the used by,

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and we can see if there's more than one used by,

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there's a comma.

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So a little shell scripting,

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Trick, we're going to count commas

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if that's the only time there's going to be a comma,

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the output of lsmod.

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So I've got a little script.

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It's a little bit tricky,

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but I'll walk you through it quick.

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So we're going to run the lsmod command.

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We're going to pipe it into the while,

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and then everything we print in the while

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is going to get piped into sort numerically.

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So the last line will have the biggest number,

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and then we're going to read each line

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of output into a variable called line.

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We're going to echo that into a tricky set here,

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and that was the hint.

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So this expression right here with the hat,

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and the comma in square brackets

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means a character glass

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of all characters except for comma.

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And we're substituting all characters

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except for comma, for nothing

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across the whole line.

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That's the G there.

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So what that means is the only thing

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left on the line are going to be all the commas.

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And then we're going to count

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the number of characters left.

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That's the number of commas,

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and we're going to put that

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in a variable called commas.

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Then we're going to echo out

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the value of commas and then the line.

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So the first thing, output will be the number.

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And then when we sort the line,

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we'll be sorting by the number.

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So let's give that a try,

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and everything scrolls off.

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And then we look at the last line there,

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it says there's five used by for X tables,

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and it lists XT contract and T compact so forth.

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Looks like five of them there.

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The next question was,

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what's the largest use count?

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Perhaps having to do with

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the number of processes,

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say using a module.

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So remember lsmod,

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that number in the third column is the use count.

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So scsi_transport_iscsi is a 1,

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802 1q is a zero.

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LLC is a 2 and so forth.

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So I've got a script to help with that too.

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Largestcount.sh.

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So again, we're going to pipe lsmod

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into a while loop,

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and then we're going to use a hawk.

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It's a quick little hawk thing.

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This prints the third column, prints the number,

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and then we're going to echo out

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the number and the line.

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So again, the first thing will be a number,

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and we're going to sort numerically.

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So let's run that.

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And at the end there, we got 21.

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NF tables is in use.

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21 times.

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X tables only used five times, right.

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So big difference there.

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And then the last question was,

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number of dependencies.

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So that has to do with module dependencies.

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So let's go to lib/modules

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our kernel version directory.

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And remember, modules.dep

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has a line per module.

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It's got the path name for the module,

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then a colon,

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then a list of the dependencies

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separated by a space.

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So if we look at a script for that,

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back in my home directory,

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we're going to do another while,

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but instead of a command,

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we're going to read from a file.

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So we do a input redirection there.

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So again, we're going to have

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the variable line be each line in this file.

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We're going to echo that into another

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tricky little set here.

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This is not square bracket.

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So this hat here means beginning of the line.

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So we're going to go from

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the beginning of the line up to the colon,

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and get rid of everything.

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So that gets rid of like the path

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right to a module,

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the first part of the line up to the colon.

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And then what'll be left are the dependencies.

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And those are separated by a space,

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and there's no space in path names

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in Linux here.

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So if we count the number of words,

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that's like counting the number of those paths.

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So that'll be the number of dependencies.

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Let's give that a try.

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And they all come out sorted.

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But at the end here, the last one is 11.

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So this MLXSW spectrum

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depends on 11 modules that have to be loaded

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before you can load that one.

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All right.

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I hope that gives you a feel for dependencies,

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and a little bit of scripting challenge.