Update README.md

README.md

@@ -27,6 +27,7 @@ Git advantage:
     - Remote & local:
         - Remote: hosted elsewhere
             - Enable collaboration
+            - Backup
         - Local: right here
         - `origin`? Just default remote name
     - `git remote rm/add/...`
@@ -47,6 +48,7 @@ Git advantage:
     - Current snapshot
         - Analogy: game checkpoint
     - ID: SHA-1
+        - Hash tree structure, not content
     - Internal:
         - Save in blobs
         - Another aspect of git: **key-value DB**!
@@ -170,13 +172,14 @@ Git advantage:
             - `^` == `^1`
             - `^3`: third parent
             - Equal `~` if **no** merge commit along the path
-            - Cause: DAG != tree
+        - Why 2 methods?
+            - DAG != tree
 
         ```mermaid
         graph BT
             classDef master fill:#418a44;
 
-            subgraph ref_from_HEAD
+            subgraph ref_each_node_from_HEAD
                 C1((C1));
                 C2((C2)) -- "HEAD~4" --> C1;
                 C3((C3)) -- "HEAD~^2~~" --> C1;
@@ -401,8 +404,9 @@ Git advantage:
             - Rebase: rewrite history (replay)
         - Conflict is inevitable. Resolving is down to us.
 
-2. Move commit around
+2. Move commit around & Rewrite history
     1. Cherry-pick
+
         Manually copy commits then add it over `HEAD`
 
         ```bash
@@ -416,6 +420,7 @@ Git advantage:
             - Reorder commits
             - Pick neccessary commits
             - Squash commits
+            - Split commits
         - The Golden Rule of Rebasing still applies:
             - NO rebase on PUBLIC
             - Use rebase to cleanup before push
@@ -423,16 +428,54 @@ Git advantage:
             - Merge doesn't meant to *rewrite history* like rebase
 
         ```bash
-        # Need to know the starting commit
         git rebase -i HEAD~10
         ```
 
+    3. Change latest commit
+        - `git reset HEAD~1`
+        - `git commit -m amend`: Remove latest commit, stage all change, ready to commit
+
+## Git remote
+
+### Common flow
+
+```bash
+# Get remote repo to local 1st time
+git clone repo
+
+# Get remote changes to working directory
+git pull remote branch
+# ... is equivalent to
+git fetch remote branch    # Get remote changes
+git merge remote/branch    # Apply those changes
+
+# Push changes to remote
+git push remote branch
+```
+
+### Refspec & Tracking
+
+1. `origin/master` vs `origin master`???
+    - `origin/master`: refspec = branch
+        - A local copy of `master` on `origin`
+    - Why no `git pull origin/master`, or `git pull origin origin/master`?
+        - The distinction is valid on local only
+
+2. `origin/master` and `master`???
+    - `master` **tracks** `origin/master`
+        - Pull: changes are automatically merged to `master`
+        - Push: changes are automatically merged to `origin/master`
+    - Manually specify tracking:
+
+        ```bash
+        git checkout -b notMaster origin/master
+        ```
+
 ## Git Internal
 
 1. How git stores data (or what a commit actually is)
     - Git stores, and each commit is, snapshot
-        - Not diff
-        - The main difference between Git & other VCS
+        - Not diff -> main difference between Git vs others
         - Hidden cause: distributed vs centralized
     - Snapshot is large, how to minimize?
         - Refer to unchanged file in previous snapshots
@@ -440,3 +483,6 @@ Git advantage:
         - Compress
 
 2. Hashed tree? Distributed? Sound familiar...
+    Is git a blockchain???? No!
+    - Git allow history rewrite
+    - Git doesn't enforce verification (proof of work)