Notes on git tags and refs.

notes/.obsidian/plugins/obsidian-to-anki-plugin/data.json

@@ -231,7 +231,7 @@
     "_journal/2024-02/2024-02-27.md": "f75a0d04a875aeee932343dae0c78768",
     "filesystems/index.md": "cbd2b0290a3ba3b32abec4bd8bfefad5",
     "filesystems/cas.md": "34906013a2a60fe5ee0e31809b4838aa",
-    "git/objects.md": "e9b98576291ca04496c2f0863f526cfa",
+    "git/objects.md": "43d825371e820802f2402034fad89480",
     "git/index.md": "83d2d95fc549d9e8436946c7bd058d15",
     "encoding/integer.md": "d4866b6e236c3a67631d03582996eca2",
     "_journal/2024-02-29.md": "f610f3caed659c1de3eed5f226cab508",
@@ -298,10 +298,11 @@
     "x86-64/index.md": "4769ab45ca374c4225c9c4099220be82",
     "_journal/2024-03-21.md": "a2572d2d5be0ee7c7f066d846e2f3e77",
     "_journal/2024-03/2024-03-20.md": "0a73ce399d275fe6ee3134a812f3f4f9",
-    "_journal/2024-03-22.md": "6c14bacf3e8834359f8512b7d7055acc",
+    "_journal/2024-03-22.md": "8da8cda07d3de74f7130981a05dce254",
     "_journal/2024-03/2024-03-21.md": "cd465f71800b080afa5c6bdc75bf9cd3",
     "x86-64/declarations.md": "60f5b240ea5565b33dc3585169fc41b1",
-    "x86-64/instructions.md": "c4b116179d2bd1f9510437e000f9c63d"
+    "x86-64/instructions.md": "c4b116179d2bd1f9510437e000f9c63d",
+    "git/refs.md": "de99450b5a4282ae1a694492f2b7f251"
   },
   "fields_dict": {
     "Basic": [

notes/git/objects.md

@@ -517,6 +517,107 @@ Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Soft
 <!--ID: 1709674569928-->
 END%%
 
+## Tags
+
+Tags are (possibly indirect) pointers to a git object. They *usually* point to a commit but aren't required to. There are two types of tags:
+
+* **Lightweight** tags are [[refs|git refs]] that never move. These aren't really git objects in the same way the other objects are.
+* **Annotated** tags are real objects that provide metadata about the object being pointed to.
+
+%%ANKI
+Cloze
+{1:Lightweight} tags are to git {2:refs} whereas {2:annotated} tags are to git {1:objects}.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120782248-->
+END%%
+
+%%ANKI
+Basic
+Creation of which of lightweight and/or annotated tags writes a new ref to disk?
+Back: Both.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120977416-->
+END%%
+
+%%ANKI
+Basic
+Creation of which of lightweight and/or annotated tags writes a new object to disk?
+Back: Just annotated tags.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120977419-->
+END%%
+
+%%ANKI
+Basic
+What two kinds of git tags are there?
+Back: Lightweight and annotated.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120782251-->
+END%%
+
+%%ANKI
+Basic
+What do git tags point to?
+Back: Any git object.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120782253-->
+END%%
+
+%%ANKI
+Basic
+What do git tags *usually* point to?
+Back: Commits.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120782256-->
+END%%
+
+%%ANKI
+Basic
+What primitive type does a lightweight tag correspond to?
+Back: A git ref.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120782258-->
+END%%
+
+%%ANKI
+Basic
+What primitive type does an annotated tag correspond to?
+Back: A git object.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120782261-->
+END%%
+
+%%ANKI
+Basic
+How many pointers does a lightweight tag introduce?
+Back: One.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120782264-->
+END%%
+
+%%ANKI
+Basic
+How many pointers does an annotated tag introduce?
+Back: Two.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120782267-->
+END%%
+
+%%ANKI
+Basic
+Why is the term "tag object" a slight misnomer?
+Back: A lightweight tag is just a ref, not an object.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120782269-->
+END%%
+
+%%ANKI
+Cloze
+Git objects are to {`.git/objects`} whereas git references are to {`.git/refs`}.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120782272-->
+END%%
+
 ## References
 
 * Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).

notes/git/refs.md

@@ -1,5 +1,5 @@
 ---
-title: References
+title: Refs
 TARGET DECK: Obsidian::STEM
 FILE TAGS: git
 tags:
@@ -8,7 +8,11 @@ tags:
 
 ## Overview
 
-A **reference** is essentially a file containing an oid. The name of the file can then be used to reference the oid. A **symbolic reference** is a file containing the name of another reference.
+A **reference** (or **ref**) is essentially a file containing an oid. The name of the file can then be used to reference the oid. A **symbolic reference** is a file containing the name of another reference. The primary refs are:
+
+* heads (i.e. branches)
+* remotes (i.e. remote branches)
+* [[objects#Tags|tags]]
 
 %%ANKI
 Basic
@@ -50,6 +54,13 @@ Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Soft
 <!--ID: 1710454031271-->
 END%%
 
+%%ANKI
+Basic
+Where on disk are git remote branch refs stored?
+Back: `.git/refs/remotes`
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+END%%
+
 %%ANKI
 Basic
 Where on disk are git remote branch refs stored?
@@ -192,6 +203,37 @@ Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Soft
 <!--ID: 1710454758079-->
 END%%
 
+%%ANKI
+Cloze
+Branches are to {`refs/heads`} whereas remote branches are to {`refs/remotes`}.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120782236-->
+END%%
+
+%%ANKI
+Basic
+What is the primary distinction between local branch refs and remotes?
+Back: The remotes are considered read-only.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120782238-->
+END%%
+
+%%ANKI
+Basic
+What safeguard does git employ to keep remotes read-only?
+Back: It never updates `HEAD` to point to a remote ref.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120782241-->
+END%%
+
+%%ANKI
+Basic
+What is prevented by git never updating `HEAD` to a remote ref?
+Back: One can't update the remote ref with a commit.
+Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
+<!--ID: 1711120782244-->
+END%%
+
 ## References
 
 * Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).