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Linux has many different ways

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of accessing documentation that will help you go through

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and understand all the key functions of Linux.

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Now, there's online help,

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there's FAQs, mailing lists,

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there's also manual pages inside of Linux itself.

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Today we're going to focus a lot on the manual function

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and we're also going to use an example

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to have a test case

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to get the best option for our organization.

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The first command we're going to test out

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is the apropos command.

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Now, the purpose of the apropos command

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is to allow the user to search through all the manuals

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for a keyword and a description

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or synopsis of a manual.

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For example,

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you use apropos search.

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Now, if you look at the results here,

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you will see that the apropos command uses the search

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and it parses through all of the commands

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that can potentially use a search function.

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And it gives us a list to the left of the commands

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and the descriptions to the right,

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that allows us to pretty much do a search function.

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Now again, Linux is very complex,

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and it can get very in-depth

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with a lot of different search features

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tailored to our organizations

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or what us, as Systems Administrators, need to do,

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and try to get the best results for us.

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Now, another example we're going to use

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is one that uses the apropos,

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but this time I'm going to use pattern.

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Now, we see we also have another set of commands

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that could search for patterns

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within, just say, file contents or logs.

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It's going to be very useful for us as Systems Administrators.

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Now, for this example, we're going to use grep.

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We're going to focus a lot on the grep command,

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which is very useful and it's used a lot

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as a Systems Administrator.

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At this point,

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we're going to test out the man command on grep.

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Grep searches the named input files,

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or standard input if no files are named,

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or if a single hyphen minus is given as a file name,

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for lines containing a match to the given pattern.

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By default, grep prints the matching lines.

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So we see grep uses a pattern,

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and we can get all this information from the description.

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We'll look at the synopsis.

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You see grep, options, the pattern, and a file.

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So as you go through,

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you'll see all the available options

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and then the pattern is what you're looking for,

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typically a string.

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If you want to look for a specific file

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or look through a specific file,

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that's where you will insert that value there.

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Okay, we're just going to scroll down.

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See all the available options here?

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Now, it's very similar to the less command

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where you use space,

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page up, page down.

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As we see, grep is pretty extensive.

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It's a lot of different information,

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a lot of different commands

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that we can use for this thing, all right?

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Now, when we're using the manual,

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we can use forward slash case.

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It's going to be example, we're going to search the manual

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for the instance of the word case.

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All right, so we see every instance

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of case used in the manual.

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The dash i will ignore

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the case of the word that we're using.

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So that means it doesn't matter

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if it's uppercase or lowercase,

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it will return the line of the file based off the word,

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and it's case insensitive.

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And we press the N

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to go to the next indication of the word case in the file.

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Looks like there's no more.

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Now we can do

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Shift N to go back if we need to.

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Little gee whiz there.

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Now we have a little information about grep.

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This is a good example.

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Let's test it out.

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Use the I option.

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Remember that means sed.

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I'm just going to search for

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any word,

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ignoring the case.

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I'm going to use my file.

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It's going to return any line in that text

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that contains those characters.

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And we see that ran through successfully.

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Now let's look up some more information about grep.

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So we're going to go to usr,

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share, slash,

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doc directory.

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And this directory contains a lot more information

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about different commands we would like to look into.

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So as we see,

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this is a catalog of all the documentation relative

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to different commands and their versions.

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So we're going to search grep here

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and remember to use our trusty tab command.

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Let's see

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CD, sorry,

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grep with a tab here.

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So now we'll go to this directory, list all the contents.

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And now we see we have all the documentation for grep

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within this directory here.

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Now let's get the news,

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see what it has to say for us.

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All right. So we're able to look at

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documentation information about grep.

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This is a lot of good information that you can use directly

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on the command line without having to search

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any third party files or anything like that.

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Bug fixes, things of that nature.

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All right, let's get out of here.

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To conclude, we just used the manual function

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to help us look up some information

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about different commands.

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For this example we used grep,

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which is something that you're going to use very often

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as being a Systems Administrator, especially for Linux.

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So I hope this helps

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and I'll see you again in the next video.