Name: Linux - 計劃任務的Cron作業(crontab) (Linux - Cron Jobs for Scheduled Tasks (crontab))
Uploaded: 2021-01-14T10:18:23.000Z
Duration: 21 min 22 s
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please go to the line the computer guy dot com in order to view schematics, code and Maur for the projects that you are learning about, welcome back.

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So in today's video, I'm going to show you how to use a tool called KRON Tab to be able to schedule events within your Lennox environment.

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So when I talk about scheduling the events, basically what this means is you're going to be able to put in a full fledged command something, let's say, possibly deleting cached files on your server, possibly optimizing a database, maybe even running analytics from the command lines.

What you're going to be able to dio is you're going to be of a schedule win.

What you do is basically you put the time or how often you want the event to occur.

You put the full command in, and then basically you say the file and then that will run.

So if you say every minute or every hour or every Wednesday, that type of thing, basically, that command will run on that schedule.

And so this could be very important in the Lenox world again.

A lot of times you do things such as you cache files or possibly you need a data bass bass optimized or even again.

You need an anti virus software to run every once in a while.

And so using the chron time will allow that to happen.

This can also be very important if you're using off the shelf packages on your Lennox server.

So let's say you're using some kind of, let's say, content management system something like that.

They may require that you use the CHRON tab in order to schedule certain events to happen so that the content management system will be able to work effectively.

Now when you start dealing with Crime Tab, the thing that I want to tell you the thing that I want to tell you his crime tab is incredibly simple.

Unfortunately, he was designed by Lennox people.

So what should be an incredibly simple thing, which is incredibly simple, turns out to be a bit of a mess when you actually go and then you try to actually use it in the real world.

So one of the things that I do want to warn you whenever you're using the Chron tab is that when you create your KRON tab tasks that they will be created for each user that you have on your Lennox system.

So if you have multiple users on your Lennox system, you can actually have multiple users with multiple different KRON tap files.

So whenever I look at my system, so right now I have the user named Bob.

I have a user named Tim and then also you have suit.

So whenever you go and you create these KRON tap tasks, they will be under each individual user account.

So this is one thing that you may be thinking about in the administrative world is possibly only using one user account for the chron tabs that you create.

The other thing to remember is that when you're dealing with Kron Tab events is that they will they will operate under the privileges of the user that you have created them for S O.

If you use pseudo Kron tab on, then you put in the command than that.

Then the event that you have happened will have root level permissions.

If I use Bob or if I use TEM for the examples that I will show you.

Then there will only have either Bob or Tim's permission.

So this is an important thing to be thinking about, Especially when you go in there.

You're trying to have events happen on your system.

If you simply do the Chron tab for your user account, you may not have the elevated permissions that are required in order to do what you want.

So what I'm going to show you today is how to edit a Krahn tap file.

So if you want to have the chrono jobs, run as you eunuch Ron Tab, space hyphen E for it.

And so then whatever you edit, whenever you add that will be based off of your account.

If you want the route user to be able to have permission to basically do the task, you're basically one of those task to be run under the root level.

You would actually do sue do crime that Kron Tab space hyphen E.

And then that will put you into the root level.

And then whatever you add it in the chron tab basically that will allow that to happen as the route user account.

So those air couple of things that you need to be thinking about whenever you use contact again, Kron Tab itself is simple.

But then you get into this mess of how it was designed by the Lenox folks s O that let's go over the computer so I can do a demonstration and basically show you how Kron Tam works in the real world.

Lt s So what I'm showing you today should work fine on you Bun too.

I do have to say when you're using Kron tohave there may be differences with the different distributions.

So if you're having some problems you're using Scent OS or something else, you might just have to do a little bit of a Google search just to verify what's going on.

We're gonna log in, Bob got 123456 We're going to hit in.

The first thing that I want to show you is just how bad?

Lennox coders are people who that developed these products for Lennox.

I want to show you how nasty they could be.

So the command that you're going to use to actually edit the contact file is Kron Tab, Space hyphen E.

But what if you're tired or if you forget and you just put in Kron to have all you do is put in contact, right?

Well, if you hit enter What you notice is you're going to get into this.

And you're kind of just stuck in whatever the hell this is.

So this is one of those little booby traps the people that coded Lennox will lead for than a dumb people.

Basically, this is this is what tries to get people to give up on Lennox and go home because you do a stupid little problem, and then you're like, I don't know how to get out of this.

So in order to get out of this, what you do is you press down control you press down X, then you press down, see?

And then, as you can see and that gets you back to the command Prompt.

So control X c If you accidentally just do contact and they can't can't, uh, can't say enough.

So anyways, now let's go and actually take a look at a real Kron tabbed file.

So again, all the crown tabbed files their individual contact files for each user.

So I'm going to be looking at Bob's contact file on one new hyphen e.

Space hyphen E for at it, I hit Enter and the first thing is going to do is going to ask me what editor I want to use eso.

Whenever you set this, you actually have to reset.

So basically this is going to become the default.

From now on, there's a command that allows you to reset it.

I have shown you folks how to use them, so I would argue you should use them again.

But you can use one of these different editors that I'm going to head enter.

And now I am editing the chron file, get all the basic information up here, and then the command is down here.

So what you're gonna do is you're actually just got to type out a whole list of these commands with whatever time you want them to run.

So the first part of the Chron let me take Let's take a look at and this is the part over here that's in yellow.

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Linux - 計劃任務的Cron作業(crontab) (Linux - Cron Jobs for Scheduled Tasks (crontab))

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