Let's stay
in touch

# Mandatory (for anything more than clone)
git config --global user.name "Your Full Name"
git config --global user.email your@email.com

# Recommended
git config --global init.defaultBranch main

# Optional
git config --global merge.tool "meld"  # see [1] for options
git config --global core.editor "vim"  # see [2] for options

# List all set options
git config --list --show-origin

    git init                        # or ...
    git init --initial-branch=main  # if init.defaultBranch is not set

    git add file
    git add folder
    git add *.txt
    git add .

      git commit -m "fix server crash, resolve #5"  # shortcut, only header
      git commit  # extended version, editor opens, enter header and message
  

• workspace  📂
• Your filesystem
• index  🕒
  • Staging area
  • Files wait patiently to be committed
• local repository  🗂️
  • Contains branches, commits, history, etc.
• upstream repository  ☁️
  • Cloud or self-hostet Git{Hub,Lab}
  • Shared folder

---

stash  📦

• Temporary storage area
Notes: Most important slide of today Upstream Repo in a minute

$: git status         
On branch main
Your branch is up to date with 'origin/main'.

Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
	modified:   00_title.md

Changes not staged for commit:
  (use "git add/rm <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
	modified:   index.html
	deleted:    slides/environments/reveal.js

Untracked files:
  (use "git add <file>..." to include in what will be committed)
	slides/advanced_git/

    rm file.txt                    # delete files from your WORKSPACE
    mv file_2.txt file_3.txt       # move or rename files in your WORKSPACE

    rm file.txt                    # delete files from your WORKSPACE
    mv file_2.txt file_3.txt       # move files in your WORKSPACE
    git add file.txt               # ... and your INDEX
    git add file_2.txt file_3.txt  # ... and your INDEX

    git rm file.txt                # Shorthand for rm X & git add X
    git mv file_2.txt file_3.txt   # Shorthand for mv X & git add X

$: cat .gitignore
  # don't track passwords.txt
  passwords.txt
  # ignore *.tmp files, notice that wildcards '*' work
  *.tmp
  # but _do_ keep track of important.tmp
  !important.tmp
  # ignore 'logs' directories _anywhere_
  **/logs
  # ignore debug-a.log ... debug-z.log
  debug-[a-z].log

    # Get repo from an UPSTREAM REPOSITORY, creating a LOCAL REPOSITORY
    git clone https://gitlab.com:OleMussmann/my_project.git  # or...
    git clone git@gitlab.com:OleMussmann/my_project.git

    # Get latest updates from the UPSTREAM REPOSITORY, and merge them
    git pull git@gitlab.com:OleMussmann/my_project.git
    # Which is shorthand for:
    # Get latest updates from the UPSTREAM REPOSITORY
    git fetch git@gitlab.com:OleMussmann/my_project.git
    # Merge the remote changes to your local branch
    git merge <current_branch> <origin/current_branch>

    # Push changes from your LOCAL REPOSITORY to the UPSTREAM REPOSITORY
    git push git@gitlab.com:OleMussmann/my_project.git

$: git branch                         # list existing branches
    existing_branch
  * main
    old_branch
 
$: git switch existing_branch         # switch to an existing branch
$: git branch
  * existing_branch
    main
    old_branch
 
$: git switch -c new_feature_branch # c_reate (and switch to) branch
$: git branch
    existing_branch
    main
  * new_feature_branch
    old_branch
 
$: git branch -d old_branch           # d_elete a branch
$: git branch
    existing_branch
    main
  * new_feature_branch
 
# new branches have to be explicitly pushed to a remote:
$: git push -u origin new_feature_branch  # u_pstream: origin

• origin is an alias for the UPSTREAM REPOSITORY URL

$: 
 
 
 

          "v1.0"
            |
main (m1)--(m2)--(m3)
                  |
                 HEAD # default, HEAD points to the tip of "main"
 
 

$: git switch --detach v1.0  # notice the mandatory --detach flag
 
 
 

          "v1.0"
            |
main (m1)--(m2)--(m3)
            |
           HEAD (detached)  # sounds worse than it is
 
 

$: git switch --detach v1.0  # notice the mandatory --detach flag
$: edit files; git add .; git commit -m "edited stuff";
 
 

          "v1.0"
            |
main (m1)--(m2)--(m3)
             \
             (x1)  # ephemeral, "virtual" branch
              |
             HEAD (detached)

$: git switch --detach v1.0  # notice the mandatory --detach flag
$: edit files; git add .; git commit -m "edited stuff";
$: edit more; git add .; git commit -m "edited more";
 

          "v1.0"
            |
main (m1)--(m2)--(m3)
             \
             (x1)--(x2)  # ephemeral, "virtual" branch
                    |
                   HEAD (detached)

$: git switch --detach v1.0  # notice the mandatory --detach flag
$: edit files; git add .; git commit -m "edited stuff";
$: edit more; git add .; git commit -m "edited more";
$: git switch -c "new_branch"

          "v1.0"
            |
main (m1)--(m2)--(m3)
             \
new_branch   (n1)--(n2)  # proper branch, will go down in history
                    |
                   HEAD

    git switch -c new_feature_branch   # c_reate (and switch to) new branch
    # do things on new_branch, like adding and committing
    git switch main                    # switch to target branch
    git merge new_feature_branch       # merge new_feature_branch into main

$: git tag                           # show all tags
  v1.0
  v1.1
$: git tag -a v1.2 -m "new gui"      # a_nnotated tag with a m_essage
$: git tag found_bug_in_this_commit  # lightweight tag: bookmarks
$: git push origin v1.2              # push a single tag
$: git push --tags                   # or push all tags

$: git switch --detach v1.0          # detach head and switch to a tag

Differences

git diff file.txt                   # WORKSPACE - INDEX
git diff <commit> file.txt          # WORKSPACE - COMMIT HASH
git diff HEAD file.txt              # WORKSPACE - LOCAL REPO (COMMIT H. = HEAD)
git diff --staged file.txt          # INDEX - LOCAL REPO (HEAD)
git diff --staged <commit> file.txt # INDEX - COMMIT HASH

$: git diff      # Omit filename to show _all_ changed files
diff --git a/file.txt b/file.txt
index 00dedf6..02ef113 100644
--- a/file.txt   # old version
+++ b/file.txt   # new version
@@ -1 +1 @@      # one line changed
-abcde           # removed lines
+new line here!  # added lines

    # try tab completion, a file name or a commit hash!
    $: git log
    # HEAD points to the latest commit in the LOCAL REPOSITORY
    commit 0fb599d96521bd27b05b0a6f963ba6ab903d349c (HEAD -> main)
    Author: ole <gitlab+account@ole.mn>
    Date:   Mon Jun 13 11:07:30 2022 +0200
    
        add content to README
    
    commit 89d8a1b57f2440693aff2f7b5003201836aa24d4
    Author: ole <gitlab+account@ole.mn>
    Date:   Mon Jun 13 11:06:51 2022 +0200
    
        create README.md
     
     

    # try tab completion, a branch, tag or a commit hash!
    $: git show 0fb5  # four hash characters are enough
    commit 0fb599d96521bd27b05b0a6f963[...] (HEAD -> main)
    Author: ole <gitlab+account@ole.mn>
    Date:   Mon Jun 13 11:07:30 2022 +0200
    
        add content to README
    
    diff --git a/README.md b/README.md
    index e69de29..8824ebc 100644
    --- a/README.md
    +++ b/README.md
    @@ -0,0 +1,3 @@
    +Hi! I am a README file.
    +
    +I have content.

Blaming!
(... or "who changed a file"?)

# try tab completion or a file name!
$: git blame file.txt
e546a240 (ole 2022-06-10 11:12:27 +0200 1) new line here!
682bc7ca (ole 2022-06-10 11:19:20 +0200 2) and another one
a9a390b3 (ole 2022-06-10 11:20:05 +0200 3) many
a9a390b3 (ole 2022-06-10 11:20:05 +0200 4) more lines

$: git status         
  On branch main
  Changes to be committed:
    (use "git restore --staged <file>..." to unstage)
  	new file:   staged_file
 
  Untracked files:
    (use "git add <file>..." to include in what will be committed)
  	workspace_file
   
$: git stash -u  # Optional -u to include u_ntracked files
  Saved working directory and index state WIP on main: [...]
 
$: git status
  On branch main
  nothing to commit, working tree clean

$: git status
  On branch main
  nothing to commit, working tree clean
 
$: git stash list
  stash@{0}: WIP on main: 50f8199 add committed_file  # only one item
 
$: git stash apply stash@\{0\} # Omit stash name for latest
$: git stash apply             # Use latest stash
$: git stash apply --index     # Optional --index to also apply INDEX
  On branch main
  Changes to be committed:
    (use "git restore --staged <file>..." to unstage)
  	new file:   staged_file
 
  Untracked files:
    (use "git add <file>..." to include in what will be committed)
  	workspace_file

# Omit stash name for latest
$: git stash branch new_stash_branch stash@\{0\}

• Do a fresh git clone into a separate folder
• Work in your changes
• Push your changes
• Delete your original folder (optional)
--- ## By Hand

$: git pull  # Oh no, a merge conflict! (Don't panic, I've got this.)
  [...]
  From https://renkulab.io/gitlab/renkuaccount/git
     c297618..09f2cc8  main       -> origin/main
  Auto-merging file.txt
  CONFLICT (content): Merge conflict in file.txt
  Automatic merge failed; fix conflicts and then commit the result.
 
$: git status  # git status shows me what's wrong
  On branch main
  Your branch and 'origin/main' have diverged,
  and have 1 and 1 different commits each, respectively.
    (use "git pull" to merge the remote branch into yours)  # Not so helpful, it failed
 
  You have unmerged paths.
    (fix conflicts and run "git commit")  # Helpful!
    (use "git merge --abort" to abort the merge)  # Panic button, good to know
 
  Unmerged paths:
    (use "git add <file>..." to mark resolution)  # git assumes i'm happy after 'add'
          both modified:   file.txt
 
  no changes added to commit (use "git add" and/or "git commit -a")
 
$: git diff  # git diff shows me affected lines (phew, does not look too bad 😅)
  diff --cc file.txt
  index 2054524,f15ccdf..0000000
  --- a/file.txt
  +++ b/file.txt
  @@@ -1,5 -1,5 +1,9 @@@  # merged lines 1-5 ("file a"), 1-5 ("file b") to lines 1-9 ("file c") ?!
    text text
    all the same everywhere
  ++<<<<<<< HEAD               # Diff start
   +line edited locally        # Part from HEAD ("file a")
  ++=======                    # Separator
  + line edited on remote      # Part from remote ("file b") (commit hash 09f2c[...])
  ++>>>>>>> 09f2cc8e449905494d3ca61d78c5b071d62db1cf  # Diff end
    more same lines
    no conflicts down here
 
$: cat file.txt  # Looking at the file.txt content. Aha! This is "file c"
  text text
  all the same everywhere
  <<<<<<< HEAD              # I should remove these control lines
  line edited locally       # I can keep this line ...
  =======                   # (remove)
  line edited on remote     # ... or this line. In fact, I can edit the file however I want!
  >>>>>>> 09f2cc8e449905494d3ca61d78c5b071d62db1cf  # (remove)
  more same lines
  no conflicts down here
 
$: [edit file.txt, fix conflicting lines, remove control lines]
 
$: git add file.txt
 
$: git commit -m "resolve merge conflict"
  [main 0835b22] resolve merge conflict
 
$: git push  # All clear! 😃
  [...]

--- ## With a mergetool: vimdiff

    git mergetool --tool=vimdiff

- Also show LOCAL, BASE (best common ancestor), REMOTE - vim is about everywhere - Difficult to learn, hard to master, worth knowing the basics! --- ## With a mergetool: meld

    git mergetool --tool=meld

- Merge to "best common ancestor" (middle) - GUI tools like meld are more intuitive - Not available in CLI environments

# No need to commit yet again! Make amends instead.
git commit -m "this should be all files"
git add dang_i_forgot_this_one.txt
git commit --amend -m "this should be all files"  # same commit!

$: ls
  EDIT.txt
  DELETE.txt
$: git add .
$: git commit -m "add files"
$: rm DELETE.txt  # remove from WORKSPACE but not INDEX!
$: ls
  EDIT.txt
# edit EDIT.txt
$: git status
  Changes not staged for commit:
    (use "git add/rm <file>..." to update what will be committed)
    (use "git restore <file>..." to discard changes in working directory)
          deleted:  DELETE.txt
          modified: EDIT.txt
$: git restore EDIT.txt 
$: git restore DELETE.txt
$: ls
  DELETE.txt  EDIT.txt

$: git restore --source stash_name/branch_name filename

$: git status
  [...]
  Changes to be committed:
    (use "git rm --cached <file>..." to unstage)
  	new file:   SENSITIVE_PASSWORDS.txt  # Uh oh!
  	new file:   README.md
$: git rm --cached SENSITIVE_PASSWORDS.txt
  rm 'PASSWORDS.txt'
$: git status                   
  [...]
  Changes to be committed:
    (use "git rm --cached <file>..." to unstage)
  	new file:   README.md
   
  Untracked files:
    (use "git add <file>..." to include in what will be committed)
  	SENSITIVE_PASSWORDS.txt