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So let's take a look at our tab again.

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Let's go Chrome tab with the E option and we've opened it up.

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See, it's remembered that Nano is our editor.

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And just so just in case you're interested, if you go on to your home directory and you look at your,

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your all the files with LS Dash a there's a hidden file here called selected editor and it's that file

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that stores your preference for for editor.

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So in here, if we look at dot selected editor, you can see you can change that if you want by putting

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the path to the editor that you want to have.

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Or alternatively, you could just type the select editor command and it would give you the choice again.

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But I'm going to keep it to Nano and leave it like that.

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But that's how if you wanted to change the editor later on, maybe you get better with another command

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line editor.

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That's how you can change it.

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So let's go on cron tab dash e and now what we're going to do is we're going to look at some more advanced

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options and more advanced ways that you can do some scheduling.

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We can add as many rows as we like in this cron type and they'll all work exactly the same.

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So I'm going to make a new row and look at some more advanced scheduling opportunities.

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So for example, let's say I want to run something exactly at the hour and 15, 30 and 45 minutes past.

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Okay.

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So I don't just have to have one option here.

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I could have zero, comma, 15, comma 30, comma, 45.

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That's going to be my first column.

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Right?

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So this is going to be the minute I can have a zero past 15 minutes past, 30 minutes past and 45 minutes

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passed.

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Notice how I've got commas but no spaces.

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You're not allowed to have any spaces because spaces separate the columns.

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So that would be like my first my first column.

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I could then space this stuff over.

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So I got a bit more space and now I could say, okay, run it at every hour, every day of the month,

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every month, every day of the week.

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And then whatever command I wanted to happen here.

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So something like Hello Echo, hello, for example.

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And this would run at exactly as the hour turned.

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And 15 minutes past the hour.

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30 minutes past the hour and 45 minutes past the hour or quarter to the hour or I could just say more

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simply run every 15 minutes and the way I do that is star then a slash 15.

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Now that says run every 15 minutes, I could say run every 5 minutes by star slash five or every 3 minutes

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star slash three every 7 minutes star slash seven or star slash 15, like I said, for every 15 minutes.

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But what about what if I wanted to run every 15 minutes, every three days?

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Let's say?

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So a lot of what I do is I'd keep the hours the same and I'd go to the days of the month option and

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do star slash three now.

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So every three days.

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So let's say on the first of the month, the fourth of the month, the seventh of the month, and so

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on, on those days it'll run every 15 minutes.

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So you can see how this kind of works here.

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What if I wanted the command to run once a week at 2359 on a Sunday, only in December and January 23,

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59 on a Sunday, but only in December and January.

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Well, how do we do that?

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Let's make another roll.

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We'd say let's to 23, 59.

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So 59 is the minute.

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The hour is going to be 23.

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It doesn't matter which day of the month, it doesn't really actually the month does matter only January's

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and December.

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So January's and December's day of the week, only Sundays.

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Okay.

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We could say because we can.

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Okay, so there we are.

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Now what we've got 23, 59 every day of the month.

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But so what this is going to do 2359 in January, in December, but only on Sundays.

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So there we are.

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And it's going to echo because we can have for example, now there's a great website called Cron Tab

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Dot Guru that you can take a look at and play around with to see what different Cron tab expressions

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mean and I'll put a link to it in the resources section.

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It's awesome.

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Okay.

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But a great use of cron is to schedule automated backups of the file system.

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So let's say we want to run weekly backups every Friday at 2359 for every month of the year.

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So if I delete these, these examples here, delete these.

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So 2359 on Fridays for every month of the year.

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So we know that 59 is the minute we know the hour is 23.

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It doesn't matter the day of the month like numerically, it doesn't matter whether it's the first or

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the seventh, just every Friday of every month of the year, but only on Fridays.

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And then we'd put the command, which is going to back up our stuff and, you know, that's how it would

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work.

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And but we know how to do this because we can make a script for it.

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So let's save our cron tab so far just like that.

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And you can see it's work 24 lines.

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But if I actually look just by the way, while we've been editing that, if I look in the text, you

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can see we've got so many more hello worlds being added to that as our cron.

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Her command that we set before has been continuing to run.

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So that's really cool, right?

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It's automated and it's running.

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In the background.

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All right.

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So let's set up the script that we want to run now.

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You remember in the last few videos when I was telling you about bash scripts, we made a folder called

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Bin.

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And inside that bin folder is where we started putting our scripts.

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And we had this one file called Backup.

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So let's take a look inside that backup script again.

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Well, in here, what it does is it compresses into into a archive on our desktop, every single one

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of the contents of our documents, downloads, desktops, pictures and videos, folders.

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And it also outputs some the error, like the standard error, like the, the log messages that come

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from the command into the, the Bitbucket.

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So they're just sent to, to the void.

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They're no longer printed to the screen.

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Okay.

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So this is good.

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This is this is going to do a backup for us.

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Let's say that actually, instead of sending them to the desktop, let's say that in our in our home

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directory, let's say let's say we made a directory called backups.

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I spelled that wrong.

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So if I rename backups with two S's into just backups with one s, there we go.

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We've now got a folder called backups and let's say we wanted to save the backups in there.

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So if we go to the bin folder and we edit our backup script now we can say, okay, go into instead

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of our desktop, go to our backups folder and then save the backup.

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GZ That's good and that's good for that.

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But what we want as well is we want to also log the date and time that the backup was created into a

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log file.

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Now the way that we could do that is we could use the date command and we could append that data to

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a file in our backups folder called, let's say, backup backups log.

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Why don't we say that?

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Okay.

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So we're going to call it backups log.

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And that's just going to keep in there the date and time that the last log happened.

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So if we save that, actually, we could we could make it a bit more advanced.

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We could actually now let's leave it like that.

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Let's not make this any more complicated than it needs to be.

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Okay?

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So we're going to take that date and we're going to append it to our backups log file.

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And you can see here that I'm using the double arrows to make sure that as this script runs, each time

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it's going to it's going to add it.

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So the file gets longer as time goes on.

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Okay.

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So we've now got this script that we want to run.

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And if we've run it just we just run backup from anywhere.

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If we run backup, you can see that.

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Now, if I just put this back to a normal size, if we go into our backups folder, we've now got backup

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star GZ and we've also got this backups log.

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If I open with that with nano backups log, you can see that it's logged the date and time.

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So if I just remove remove everything in here using RAM, you can see they've all disappeared.

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So we're good.

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We know that script works.

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Let's try and add it to our cron tab.

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So here we are.

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We've said that we want every Friday at 2359.

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We want that.

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We want that script to run.

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So how can we do that?

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Well, the way we can run that is because it's a bash script.

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We'll type the bash command.

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So just bash like that and then we'll give it the path to the script that we want to run.

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So in our home directory in the bin folder, we're going to run the backup script.

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So that's all we've got to do, right?

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We just type bash and then give it the path to the script that we want to run.

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And then that script will now run at 2359 on a Friday.

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But to save you waiting all the way till 2359 on next Friday, let's go ahead and make this run every

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minute so we can watch it happen.

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So look what I'm going to do.

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Nice hack, hack, hack.

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Okay, so I'm going to cut the line and uncut the line and then cut the line again.

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So that's a nice copy and paste and I'm going to make this run every minute.

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So if we go, we're going to change all of these to stars.

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So there we go.

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Now, that should run every minute now.

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So if I write the file and close it, you can see it's installed the new cron tab.

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Now in backups, there's nothing in here.

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But if I look at the date, we can see that we've got about 40 seconds until this runs again.

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Needs to be very excited, I'm sure.

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So we've got about about 30 seconds.

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So I'm going to cut the video here and come back closer to the time.

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So here we are.

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Let's take a look.

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And it's just gone past the minute.

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So let's take a look at our backups folder and hooray, we have indeed run our script correctly.

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And if we look inside the log folder, if we look at backups log, we can see that it ran at just past

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the third minute of today.

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So the reason that it runs at just the minute past, it's just like a like, you know, there's just

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1/2 error.

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I think it's just a clock thing.

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It's, you know, the computer can only process things at a certain time resolution.

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And 1/2 is really not that much of a bad error.

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Okay.

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So it'll you'll tend to see things like this.

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I think it actually does run at exactly the time the minute goes, but the date command takes just about

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a second or so to run or something like that.

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So there's a slight delay, but really 1/2 is not bad at all.

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So now we have indeed ran a command.

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And look, it might it might even happen again.

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It might even happen again.

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So if we're at four more seconds, one more second.

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Yes.

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Now we look inside our backups log.

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Backups log.

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We can see that another one is run again just at 1/2 past the fourth minute.

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So now we are making backups every single minute.

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But that might be a bit of a a bit of a a bit of a burden on our computer here.

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So let's just go ahead control and K to delete the line and then we can save our cron tab and leave

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it so that it just runs at 2359 on Fridays.

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So there you are, guys.

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How awesome and how epic is that?

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So I'm sure you can see the power of combining together bash scripts and cron scheduling to control

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whatever you want about your computer.

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Now, these two skills together are incredibly powerful combination, and you now have the foundation

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in how they work.

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So let's have a quick recap of what we've learned in this video.

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So in this video, you took a look at how to use cron to schedule when commands and scripts should be

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run.

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And you learn that every user has what is known as a cron tab and that you can edit cron tabs using

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the cron tab command with the E option with the E standing for edit.

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Now cron tabs are text files that are broken up into many rows and you can have as many rows as you

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like.

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And each command or script has its own row and each row has six columns.

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The first five columns are scheduling information and the sixth and final column details which command

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or script should be run at that scheduled time.

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So the columns are for, for the scheduling columns.

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You've got the, the, the minutes of the hour.

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So for example, if you put 15 in that column, the command would only run at the 15th minute of each

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hour.

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So things like 11, 15 to 15, three, 15 and so on.

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Then you've got the hour itself.

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So that's a number that you can put in 24 hour clock time.

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So from 0 to 23 you've got, then the third day of the column is the day of the month.

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So again, from one to the end of the month, whatever that might be, the fourth column is the month.

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So that could be numbers with one being January and 12 being December.

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Or you can just type in capital letters the three letter version of the month.

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So Jan for January, DC, for December and so on, and the fifth column is the day of the week, so

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that could be 0 to 6 with zero being Sunday and six being Saturday.

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You could also enter seven as Sunday again if you wanted, but a good way to do it is just to enter

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the day names.

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So Mon being Monday, soon being Sunday.

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So three letter day names.

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And you also saw some advanced ways to to schedule this stuff as well.

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And a great place to look at these these scheduling things is to look at a website called Cron Tab dot

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guru.

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I'll put a link to that in the resources section.

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Um, because it's a great website for you to practice setting up these scheduling conditions, and it

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also will be useful for you at some point in the future.

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And as I should mention as well, columns can be separated by as many spaces as you like.

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All cron wants is that you separate each column by at least one space, but feel free to format each

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rows however you like.

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And you also saw in this video how to use cron tabs and batch scripts to schedule automated backups

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of your home directory, which is an incredibly useful thing to make sure that all your files stay safe

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and it built upon what you learned in the last section about file compression and archiving.

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So that's super awesome as well.

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Now the key thing that I want you to remember from the last two videos is that in Linux, practically

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anything can be edited using the command line.

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Now, since you can write bash scripts to execute these commands in a controlled sequence and then use

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Cron to schedule when these scripts should be run, you have the necessary toolkit to do whatever you

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want on your system whenever you want to do it, which is a crazily powerful combination.

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All you need now is a bit of imagination to decide what you might like to do now.

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Batch scripts are a whole massive topic in and of themselves, so we only really had time to scratch

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the surface and cover just a small bit of what they can do in this course.

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But at least now you have an understanding of what batch scripts are, how they work, and where you

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might use them.

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And if you'd like me to create a specialized course on just bash scripts, then send me a message.

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And if I get enough of you saying that you want that, then I can I can potentially put that together

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for you.

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But for what we've learned in this course so far, I want to make sure you get some practice in using

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it.

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So in the next video you're going to be getting the brief for your next project assignment.

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Now, it will be a rather simple and fun one this time, but it allow you to go off and try writing

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batch scripts and crosstabs for yourself so you can get a hands on understanding of how these incredibly

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powerful skills work.

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So for the brief of your next assignment, I'll see you in the next video.