Real Newby here trying to understand why this would not work

I’ve been playing with docker for a day or so now trying to understand enough to begin using it properly. I wanted to do this from scratch rather than just downloading other peoples images, so that I understood what went into them. So far I’ve not succeeded in much and I think it could be I am misunderstanding as my history is more systems stuff and VMs. Two things can anyone tell me why this would not work? I know it seems to be asking for a further parameter but you do not need that anywhere else…

Second, I read in some of the stuff I have gone through looking for solutions that I should not have Git embedded in my images as source management should happen elsewhere? Is this right? And does this apply to package management too as PIP seems to have been my biggest problem trying to get something working…

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By the way you have a syntax error in the command so it sets “apt” as environment variable with “get” as value and tries to execute “install git”. Not everthing is a Docker error just because you see it when you work with Docker. The error would have been the same in a virtual machine or on a physical machine, but the error message seems to be pretty clear, indicating that the executed command is “install” and not “apt-get”.