WEBVTT

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-: In last section, we learned how to start up a shell

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inside of a container the instant that it was started.

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By the way, if you have a little bit of trouble exiting

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from this by hitting control C,

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which is usually how we exit out of a container,

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remember you can either press control D on your keyboard

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or you can just type in exit like so

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and it will kick you back out.

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Now in this section, there's one very small "gotcha,"

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maybe not even a "gotcha,"

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but just a very particular thing that I want to go over

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to make sure that it's really crystal clear

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on how containers behave.

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I want you to recall back to a little bit ago

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when we were initially talking about what a container is.

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Remember that we gave this example of where Chrome

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had needed a particular version of Python

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and NodeJS needed it's own version of Python.

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And we had said that through that name spacing feature

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we can kind of imagine that our hard disc

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had two little segments carved out of it,

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and any time Chrome tried to access that hard drive

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it would get it's own segment.

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Any time NodeJS tried to access the hard drive

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it would get it's own different segment.

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And so the thing that I want to make sure is really

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crystal clear is that between two containers,

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they do not automatically share their file system.

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We're gonna do a quick demo inside of our terminal,

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just to really confirm that that is the case.

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So I'm gonna open up my terminal and I'm going to start up

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a new instance of that BusyBox image,

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and I'm gonna start up a shell inside there.

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So I'll do docker run -it busybox shell.

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So now I can list my files and folders inside of here

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and I see just these default folders.

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I'm now going to open up a second terminal window,

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and I'm going to start a second container

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with the same parameters.

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So second terminal window,

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and I'll do docker run -it busybox sh.

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Now I'm gonna open up one more terminal window,

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so this is gonna be a third one.

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And inside of here I'll do docker ps,

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and I can verify that I have two separate containers,

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both running a shell.

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Now I'm gonna go to the first terminal window

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and inside of here I'm gonna create a new file

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with touch hi there, like so.

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That's gonna create a new file called Hi There.

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There it is right there,

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I can li- run LS and I'll see the file up here right away.

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Now here's the fun part.

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We're gonna go over to the second terminal window,

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and I'll do an LS over here as well.

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And of course, I am not gonna see that file of Hi There,

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because these two running containers

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have absolutely, completely separate file systems,

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and there's no sharing of data between the two.

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Again, this is kind of a small thing, but I just wanted

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to make sure that it was very crystal clear.

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So in general, unless you and I specifically form up

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a connection between two containers,

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we really considered them to be more or less

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completely isolated from each other and totally separate.

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Alright, so that's pretty much it on the basics of Docker.

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So we're gonna take a quick pause right here.

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We're gonna come back the next section and we're gonna start

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moving on to the next big topic that we're going to cover.

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So I'll see you in just a minute.