$1.$ Readying Docker for Linux:

Play$-$with$-$Docker $($PWD$)$ is itself running on Linux. You can check what version by typing. It should return a version of Alpine Linux.

$ cat $/$etc$/$os$-$release

Let$$s invoke Play$-$with$-$docker $($PWD$)$ and load up one of the more popular version of Linux; Ubuntu:

$ docker run $-$it ubuntu $/$bin$/$bash

When ubuntu is done installing.$$ You can run the same cat command to find what version of Ubuntu you are running.

$ cat $/$etc$/$os$-$release

$2.$ Print working directory $($pwd$)$

The$$pwd$$command prints your working directory on the screen. In other words, it outputs the path of the directory you are currently working in$.$

$3.$ Make directory $($mkdir$)$