XPLab_2019

Course site for "Experimental Psychology Lab" 2019

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Project maintained by michael-franke Hosted on GitHub Pages — Theme by mattgraham

Working with a local repository

Creating a repository

• open a command line tool
• create a folder of your choice
  • e.g., mkdir my_first_git

Adding a file

• go to this directory and initialize
  • e.g., cd my_first_git && git init
• add a file called mynotes.md to the directory
• open the file with a text editor
• type some markdown & save the file
  • make sure to write several lines
• inspect the status with git status
• add the file to version control with git add mynotes.md
• inspect the status with git status again
• now commit your changes with git commit -m "my first commit"
• inspect the status with git status again
• look at the log history of your repo with git log

Add another file

• create another file called mynotes_2.md
• fill in some content of your choice
• add it to version control using the same procedure as before

Seeing current changes

• make some edits to mynotes.md
  • add text in some lines
  • delete some text in existing lines
• inspect the status with git status
  • this tells you which files changed, but not how exactly
• type git diff mynotes.md to see changes between last commit & current version
• commit these changes
• type git diff mynotes.md again

Seeing changes between commits

• you can see what changed in all files from COMMIT-1 to COMMIT-2 by typing git diff COMMIT-1 COMMIT-2 mynotes.md
  • here COMMIT-x is the commit ID (which you find in the output of git log)
• zoom in on changes in file mynotes.md with git diff mynotes.md COMMIT-1 COMMIT-2 -- mynotes.md
• type git log -p mynotes.md to get a full change history of file mynotes.md

Undoing staging

• make changes to your file mynotes.md
• stage the changes with git add mynotes.md
• look at git status (boring!)
• to unstage these changes type git reset mynotes.md
• look at git status again
• check whether your changes got lost (using what you learned above)

Undoing local changes

Single files

• type git checkout mynotes.md to undo your recent local changes
• check the status and the diff between local file and last commit

Whole repo

• change both of your files & inspect the status
• type git reset --hard to undo all local changes
• inspect status to verify

Going back in time

• retrieve the (shortened) commit ID of your first commit by git log --oneline
• type git checkout FIRST-COMMIT-ID to roll back complete to where you were in the beginning

Branching

• so far our history of developments was linear; it’s time to change that
• create a new branch with git branch silly_try
• switch to that new branch with git checkout silly_try
• add one or more lines with text at the beginning (!) of mynotes.md
  • don’t change anything else in the file!
• add & commit the changes with git commit -a -m "changes to a branch"
• look at your history now with git log --graph --oneline --all
  • we now live in a branching-time universe
  • different developments of your project live next to each other

Merging

• we will now bring parallel universes together
• switch back to the master branch with git checkout master
• merge the changes into the master branch with git merge silly_try
  • if we are lucky git will merge automatically
  • if not, there will be so-called merge conflicts
  • if you have merge conflicts, you will need to resolve them manually
• commit your changes with git commit -a -m "merged in branch silly_try"
• have a look at your history with git log --graph --oneline --all

Resolving merge conflicts

General information

• when a conflict occurs and git cannot merge automatically, it creates a new file in which both changes are kept side by side
• the user must then decide by hand which changes to keep or how to merge
• use will find tools of your taste for doing this by searching the internet

Creating and resolving a conflict

• make sure you are in branch master
• edit part of the first line of mynotes.md
• commit the changes
• switch to branch silly_try
• edit another part of the first line of mynotes.md
• commit the changes
• switch back to branch master
• merge the changes from silly_branch into master
  • use: git merge silly_branch
• you will now see a message about merge conflicts
• open mynotes.md and fix the conflict manually
• then commit your changes as usual

Working with a remote repository

Creating and linking the remote repository

• create a remote repository, e.g., on GitHub
• link your local repo to the global one with git remote add origin YOUR-REPO-URL
  • now origin is the name for your remote repo

Pushing and pulling

• pushing is when you “upload” local changes
• pulling is when you “download” remote changes
  • merge conflicts can arise just like when merging branches