I gather you have git installed. If not - do an "apt-get install git-core" or something similar.

In general:
- this is the first time I actually use git - so I am no pro either :-)
- git seems to be used in two stages:
  a) building a revision control system on your own computer
       (you do not have to use github at all!)
            With git you can build an own repository add/checkin/checkout build branches etc on your
	         computer without anything remote happening.

     see: https://product.hubspot.com/blog/git-and-github-tutorial-for-beginners
          For How to setup and use an own repository.

  b) Making your own repository "public" by "releasing" it to github.
       If you are working with a team on a project, than each member has its own
            repository on their computers. They can make changes to their own repository.
	         (also build branches etc...)

     If/when you want to make the changes "public" you PUSH your own repository to github,
          either with a new branch or to the "master". (or do a pull request - but we will not do that (yet))

-----------

First step
In our case the first step is to have the current public repository on github
your "own" repository on your computer.

In a "clean" environment, you just do:

>    git clone https://github.com/malbanGit/pitrex.git

This will setup in your current directory a "clone" of the repository master from github.
The new directoy "pitrex" will appear - with all pitrex stuff inside.
(I made a single subdirectory "software" in anticipation, that perhaps someday a "hardware"
 directory, or a "documentation" might be a thing to do...)

>    cd pitrex/pitrex/software

This is our "usual" directory, from here you can execute e.g.:

>   make -f Makefile.raspbian

etc.

Than you can work "normally" with the project.

STATUS
If you want to know your current changes, you can type
>   git status


This lists all deleted/changed/added files within the current project.

ADD
If you created new files withing the repository you must add them manually with
(you can also add directories/structures)

>   git add newfile

COMMIT
To commit (all) your changes locally - type:
(you can also commit files/directories etc)

>   git commit -a -m "comment of what changed"

(First time you commit, you might have to tell git your credentials... don't worry, git will tell you
 how. It is very helpfull!)

PUSH
To make your changes visible to other users - you also have to update our
"public" github repository. Above changes were all made locally.

To do that you use the push command - which updates the github repository with your changes.
You must have a github user with the rights to update our repository.
(Make a user - and tell me - I'll give you the rights)

>   git push origin master

(git will ask for your user name/passwd)

Your changes will be committed!

CONFLICT / PULL
If someone else "pushed" already some changes to github (which concern the same files)
- you might encounter a conflict message and the push will not be executed.

In this case you must "update" your local respository with the changes first:

>  git pull

Will update your local repository with the current version held on github.
If possible git will merge changes. If the automatic merge fails, you have to
solve the conflicts manually. (git will tell you which files, you can also do a "git status")

The files with the merge conflict have the conflicts "marked" with:

<<<<<<< HEAD
... some lines
=======
... some lines
>>>>>>> e5f71728add78ac94cff0665d234474ab9a13e19

Decide what to use and save the file

UNDO
UNDO all changes (locally from last commit)
git reset --hard


---
This avoids needing to re-enter the GitHub password (stores it in plaintext though):
git config credential.helper store
---
Show past commits:
git log

---
Return everything to a previous commit (one way to do it):
git reset --hard <commit>

 Then "git pull" to go back to the present again.

---

/usr/local/bin/gitdiff:

#!/bin/sh
git diff `git log --oneline | head -2 | tac | sed -n -e 's/^\([0-9a-fA-F]*\) .*$/\1/p'`

-----

READ THIS: got passwords may be going away, should transition to ssh keys?

https://hackaday.com/2020/09/15/githubs-move-away-from-passwords-a-sign-of-things-to-come/

  (read the comments too...)

---