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Now it's time to look at the last command, which

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is wc. It is one of the last command for text

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processors that in our lectures, that we are going

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to cover. A wc stands for word count, and what

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exactly it does. The command reads either standard

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input or a list of files and generates newline

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count, word count, and byte count. So if you just

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run wc on a file, it will give you these three

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output. Now let's get into our Linux machine. And

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I have the first command, as you all know, is to

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check the version and to get the help. So when I

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get to my Linux machine, and again, I'm logged

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into the PuTTY, and you guys know what we have to

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run, we have to run, as usual the username, and the hostname,

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and which directory we are in. And pretty much

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once we confirm, perfect, clear the screen, and now do

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wc, and I'm going to skip version. I know all of

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you guys know this already by now, these are the

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few options that it is it supports. And then the

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one of the most used one that I use as

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well, and a lot of people use is -l, which

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we'll cover in a few. So now let's get into the

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next command, which is wc file name. Let's clear

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the screen. I'm going to go to my seinfeld

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directory, and in there I have my seinfeld-characters. Let's

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cat out, and these are the

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contents. This is the content of my seinfeld-characters file.

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Perfect. Now if I do, let's

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clear the screen again, if I do wc seinfeld-characters,

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hit enter, you're going to see it will

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tell me exactly what's inside, meaning, it has 17

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lines, has 34 words, and 236 bytes. So if I wanted

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to know only the line numbers that's inside of

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seinfeld-character, I could simply do wc, word

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count, or sometimes people refer to as waca dash

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l, and seinfeld-characters, you're going to see it

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will give me only the number of lines, that is 17.

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Similarly, I could do either w or b to get the

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word count, and the byte count. So for the word, as

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you see, it'll give me 34. For the byte count, I'll

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replace it with b,

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[No audio]

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is it a byte count, why it's

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not giving me the information, invalid option minus

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b. For the byte count, hmm, that's new. Okay, let

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me check why is that, wc --help, and we will

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see, ah for the byte it's actually c. See, that's

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why it's so important for you to run wc dash dash

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help to find out the right option. Or, what's the

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other one, the big one man wc, which will also

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give you a lot of information about that specific

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command. Anyway, my slide is showing -b, that

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is okay, you could ignore it. I'll go back and fix

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it later. But for now, for this lecture, we'll go

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continue with wc -c for byte size. Also, a

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lot of people confuse this with the -c,

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meaning characters, it is not a character, it's exactly a

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byte size. So the file name would be seinfeld.

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Usually we saw a bytes and characters are

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somewhat similar, maybe a few, not exactly a few,

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two or three numbers up and down. But anyway,

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focus on wc -c, if you wanted to get the

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byte size. Alright, the next command I have the wc

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DIRECTORY, which is NOT allowed. So if you trying

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to do the wc on a directory, so let's say inside

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of my seinfeld directory, there is no directory.

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So I'll go one step back, and do ls -l to see

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which directories are there. And now I will do wc

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on seinfeld directory, hit Enter. It will say, wc:

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seinfeld/: Is a directory. So it's not going to

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give me any information that I'm looking for

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regarding lines, or word count, or bytes. Anyway,

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clear the screen. Let's go to the next one, and

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which is the ls -l command, which we will run,

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and that will give us the list of output. Again,

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this is the command one. Before we were talking

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about reading from the file, now this is reading

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from the output of a command. So if you want to

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see how many files that you have, let's say your

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boss comes to you and says hey, listen, I need the

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list of files we have in this user home directory.

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Give me the number. You go in and you quickly run

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ls -l, and wc -l, and you come back to him

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and or her and tell your boss, hey, we got 15

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files alright.

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wc is working perfectly here, and it is giving you

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the count of every line. But in fact you do not

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have for 15 files or directories you have 14. Why

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because, you see this total 280 here, this is

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something that it is also counting. So, always

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remember when you do ls -l, and wc -l,

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whatever the results that you get, always minus it

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with one. So, now you could say that I have 14

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files and directories altogether. What if I want

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to know only the list of directories in my,

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in my home directory. So, to do that, you know, to list

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the directories, you have to run the command, I

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think ls -ld, or ls -ld /homes

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/iafzal.

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[No audio]

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Okay, it is giving me,

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[No audio]

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all, okay, so this is not the right command. Anyway, I will

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look it up for what is the right command, however,

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I could still use another trick. See, that's why

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Linux is so powerful. And you do ls -l, you

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you notice that every directory starts with D. So

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what I'm going to do is I'm going to do ls -l,

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and grep for drw, because all of them, if you

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notice starts with drw, drw. So just give me

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all the directory. So by default,now, I have all

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the directories. Anyway. So now if I want to know

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how many directories I have, hit up arrow key, and

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do wc -l. So it is telling me that I have 11

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directories. Now, it is not giving me that total,

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right here, you notice, because the total will

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only give you when you only run ls -l. As

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soon as you run ls -l, and pipe it that total

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will go away, and then you will just grep for drw,

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because you're only grepping for anything that

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starts with drw. And the total does not start

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with drw. Anyway, as an exercise for

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you, go ahead and find out the command of ls -ld,

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or whatever the command is and find out which

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command will give you only the directories. I use

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the grep, it works for me perfect. But anyway,

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there is, I'm definitely sure there is a command

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and I'm sorry, I didn't know that.

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Anyway, that's for you to find out. So that's how

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you know the number of files in your directories

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in your home directory. And then the last command

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that we will run is to grep for keyword in a

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file and then get a list of it. So I'll go back to

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my seinfeld directory. In the seinfeld directory, I

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have a file seinfeld, as everybody know, so I'll

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do cat seinfeld. And here I will grep for

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seinfeld. So grep Seinfeld, in my seinfeld-characters

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file, and you'll notice there are three

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people with this last name Seinfeld. Now if I want,

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if I had let's say 20 or 30 or 1000 of those names

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that match my criteria, then how would I know how

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many were there? So simply do pipe it wc and -l,

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it will tell you there are three instances of

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your search criteria, works, perfect. I hope you

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understand now all the text processing commands, I

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have explained it in very detail. Please please do

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try them with different options and different

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scenarios and see which ones works for you and

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which ones gives you more fun to work with.

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[No audio]