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It is good to see the shell in the
context of how an operating system is typically organized.

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So it all
starts with the hardware.

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The hardware in your computer
is what you want to use.

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Now the main layer to interface the
hardware is the kernel and the kernel is

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using drivers, also known as kernel modules
that allow you to communicate with the hardware.

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But the kernel by itself
is inaccessible for the user.

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And that is why in order to
provide the user interface there is a shell.

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So at any time you type commands, you type your
commands right here. So this is the world of the user.

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Now the shell needs to send
instructions to the kernel and there is

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a very important component involved here
and that is C library libc.

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And the C library provides system
calls and these system calls are low

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level system instructions that allow your
shell to communicate with the kernel.

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And that is how commands are
dealt with in a Linux environment.