WEBVTT

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-: In the last section, we spoke about

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how we could open up a shell inside

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of a running container by using docker exec -it,

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and then passing in shell

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or just simply sh as the command that we want to execute.

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We've been talking about all this

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in the context of the exec command

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which we can use to execute an additional command

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inside of a container.

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But if we wanted to, we could also run docker run,

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the original docker run command right here

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along with that it flag

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and start up a shell immediately

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when a container first starts up.

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Now, of course, if we start up a shell

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right when the container first starts

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that's going to displace

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or keep any other typical or default command from running.

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But sometimes, it is quite useful to get a empty container

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with a shell inside of it and just being able to poke

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around and not have any other process running.

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So let's try that out right now at our command line.

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I'm gonna flip back over to my terminal.

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I'm gonna run at docker run.

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I'm gonna put on the it, so that we can attach

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to standard in on the process that we're about to start up.

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I will run the busy box image

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and then the program or the primary command

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that we're gonna execute inside the container will be sh.

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So this means start up a new container

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out of the busy box image,

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run the sh program, which is a shell

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and attach to standard in of that program.

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So when I run this, I'll be presented with a command prompt

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and just like we saw a moment ago, I can run the LS command

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I can ping google.com and hit control C to stop it.

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I can echo a message, whatever I wanna do.

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Again, this is a command that you might be using

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somewhat frequently anytime

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that you want to poke around a container.

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The downside to using docker run with it and sh

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is that chances are you're not going

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to be running any other process.

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It's a little bit more common

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that you're going to want to start up your container

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with a primary process of like maybe your web server

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or whatever it might be

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and then attached to it a running shell

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by using the docker exec command,

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wherever it is right here.

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But I just wanted you to be aware

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of this alternate use of docker run.

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All right, now one last thing I wanna cover

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in the next section, so quick break

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and I'll see you in just a minute.