Look at the first five chapters of
The Unix Programming Environment. It's an old book - really old book, and while it has a bit of obsolete info in it, it's a good intro on to how to use Unix (Linux) as a programming environment. They send a lot of command output to either lpr (print to printer command) and mail - I would just redirect the output to a file instead of using those commands. [I'm old - this book was new when I was first learning Unix.] The info in the book is a starting point. Unix and Linux have evolved well past what this book covers. I searched to see if someone had done a rewrite of the book targeting a modern version of Linux, but didn't find anything.
One thing they do in the book that likely looks crazy is using the commands "ed", "cat", and "echo" to create and edit files. While you can use a friendly visual editor or an IDE to create and edit files, learning to use these command line tools to manipulate text files is very helpful if you are looking at doing something like say ... processing a list of user names and passwords to pass on to some other command that may do something useful with said info.
With respect to Linux commands, there are thousands of them, but I found this, which might be useful, but it is far from complete
https://ss64.com/bash/
If you are trying to do X under Linux, google "how to X in bash" will likely lead to a few stackoverflow links, which can lead you to the command or commands you need to accomplish X.
I don't have any suggestions on the python front other than googling for python tutorials and finding one that works for you. If you are trying to do something specific in python, google how to do x in python and you'll likely get results from stackoverflow, which again, is a good source of info on specific howto knowledge.