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- The next utility that I
wanna talk about is awk.

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So what is awk?

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Awk is a great utility

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for performing more
complex operations on text.

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It is using advanced features that make it

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into a scripting language,

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but these advanced features
are not used that often anymore

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but awk can make complex task more easier.

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If you are going to try to find
more information about awk,

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you will find entire books
that have been written

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about awk.

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Now, why is that?

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That's because of the
history of the command.

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Awk was invented in a time
that computers did not

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have graphical screens next to them,

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and working with computers
was mainly line oriented.

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In those days,

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we needed very powerful
tools to program text cells.

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It's basically to
automatically treat text cells

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and to program manipulations
into your text cells.

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And that's where awk is coming from.

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And likewise, where set is coming from.

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That's the utility that
is going to be up next.

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The confusing thing
about it is that whenever

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you feel like,

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Hey, I wanna know more
about awk and about set,

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then you will probably end
up with one of these books

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that are describing every single feature

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of awk as well as set.

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But the thing is, most of these features

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are kind of not so useful anymore.

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So what I've done, I've
listed four examples for awk

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and these are the examples
that I want you to

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understand.

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Here on the slide, you can find them,

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if you want to experiment for yourself.

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Let me just demonstrate so

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that we can see what they are doing.

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So to start with, we have awk,

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and then the awk operation.

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The awk operation is between
single quotes and curly braces

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as we can see here.

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So we have print dollar
zero on ETC pass WD.

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Now, what is that doing?

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Well, that's just printing everything.

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How about if you make
that print dollar one,

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that's also printing.

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Is that everything?

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No, it's not everything.

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It's printing the first field,

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but if you look closely,

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then you can see it has a hard time

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recognizing the fields.

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So if you want to help awk a little bit,

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and if you want to print a specific field,

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then you need to add a field separator.

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Minus F is that in an awk environment,

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so if you use awk, minus
F colon print dollar one,

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then it knows that it needs
colons as the field separator

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and it'll be successful
in finding this field.

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Now let's do another
manipulation and that's

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awk length

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dollar zero greater
than 40 on ETC pass WD.

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Now, what is that?

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Well, it's looking for length dollar zero.

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Dollar zero is the entire line.

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And it'll only print if the
length is greater than 40,

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and you can see

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that it limits the number
of lines that we get.

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If you even make it
longer, let's make it 50,

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you can see that the number

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of lines is even getting shorter.

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And how far can we go?

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Let's try 70.

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And there, you can see
only a couple of lines.

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So this is allowing you
to do filtering criteria.

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You only want to see lines
that are longer than whatever.

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This is what you wanna do.

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Let's try to understand the
historical background of that.

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The historical background is that

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if you have a text cell
with lines longer than 40

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then they might not print correctly.

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So you might need to do an
operation and split these lines.

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And that is why a command
like this is useful.

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Okay. Last example with awk.

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Let's print the entire contents
of the past WDFL again,

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so that I can explain.

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If you look at the last line,

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that is the line that contains
the text Linda right here

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This last line, then you
can see that in past WD

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we have a couple of fields.

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The fields are separated by a colon.

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Now it's field number three,

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field number four, these are useful.

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They contain the user ID

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and the group ID, which are unique IDs.

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And that's what I want to be looking for.

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Now how can awk help us with that?

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Well, I want to use awk to find
the user ID for user Linda.

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So how am I going to do that using awk?

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Well, I am going to use awk minus F colon

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and then I'm using my search
pattern slash Linda slash

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print dollar three, for
instance, on ETC pass WD.

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And what is that doing?

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Well that is showing the user ID

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for user Linda using awk,

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and in case you're wondering

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do we really need to use awk for that?

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Well, of course not.

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You can also use different
commands to build it up.

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Grep Linda on ETC pass WD,
showing you the entire line.

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And if we next use cut
minus D colon minus F three,

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then we get the same result.

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That is something that
you will frequently see

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in Linux environments.

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There are different solutions
to get to the same result.

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And if you think

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that awk is too complex,

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I can understand that.

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Just use a combination

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of utilities that you
are more comfortable with

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and you will get there as well.

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And that's the most important
lesson to be learned

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about awk and also about set,
which will be coming up next.

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You can do pretty nice
things with these utilities,

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but you don't have to do
it with these utilities.

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You can do it in a different way.

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That's fine as well.