239 lines
7.5 KiB
Markdown
239 lines
7.5 KiB
Markdown
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---
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title: Refs
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TARGET DECK: Obsidian::STEM
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FILE TAGS: git
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tags:
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- git
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---
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## Overview
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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:
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* heads (i.e. branches)
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* remotes (i.e. remote branches)
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* [[objects#Tags|tags]]
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%%ANKI
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Basic
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What is a git ref?
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Back: A user-friendly name for referring to some git object.
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454031260-->
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END%%
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%%ANKI
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Basic
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How is a git ref realized on disk?
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Back: It is a file containing an oid.
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454031263-->
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END%%
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%%ANKI
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Basic
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What shorter terminology refers to "git references"?
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Back: Git refs.
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454031266-->
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END%%
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%%ANKI
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Basic
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Where on disk are git refs stored?
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Back: In the `.git/refs` directory.
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454031269-->
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END%%
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%%ANKI
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Basic
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Where on disk are git local branch refs stored?
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Back: `.git/refs/heads`
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454031271-->
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END%%
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%%ANKI
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Basic
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Where on disk are git remote branch refs stored?
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Back: `.git/refs/remotes`
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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END%%
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%%ANKI
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Basic
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Where on disk are git remote branch refs stored?
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Back: `.git/refs/remotes`
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454031273-->
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END%%
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%%ANKI
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Cloze
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The {`update-ref`} plumbing command is used to manage {reference files}.
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454031275-->
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END%%
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%%ANKI
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Basic
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Why is the `update-ref` command's name a slight misnomer?
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Back: It is also used to create references.
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454031277-->
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END%%
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%%ANKI
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Basic
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What plumbing command is used in favor of manually editing reference files?
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Back: `update-ref`
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454031279-->
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END%%
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%%ANKI
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Basic
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How do I complete the following command to update `master` to the new oid?
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```bash
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$ git update-ref ___ 1a410efbd13591db07496601ebc7a059dd55cfe9
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```
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Back: `refs/heads/master`
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454031281-->
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END%%
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%%ANKI
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Basic
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Git (basically) invokes what plumbing command on new branch creation?
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Back: `update-ref`
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454031283-->
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END%%
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%%ANKI
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Basic
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What is a git symbolic ref?
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Back: A git ref that points to another ref (as opposed to an oid).
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454758061-->
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END%%
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%%ANKI
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Basic
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Which symbolic ref is most commonly used?
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Back: `HEAD`
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454758064-->
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END%%
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%%ANKI
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Basic
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What does it mean to be in "detached head state"?
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Back: `HEAD` refers to an oid instead of another ref.
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454758066-->
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END%%
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%%ANKI
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Basic
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What term describes when `HEAD` is a normal ref instead of a symbolic ref?
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Back: Detached head state.
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454758068-->
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END%%
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%%ANKI
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Basic
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Where on disk is `HEAD` normally located?
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Back: `.git/HEAD`
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454758070-->
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END%%
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%%ANKI
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Basic
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What does the contents of `.git/HEAD` normally look like?
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Back: `ref: refs/heads/<BRANCH>`
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454758071-->
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END%%
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%%ANKI
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Basic
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What does the contents of `.git/HEAD` look like in detached head state?
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Back: `<OID>`
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454758073-->
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END%%
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%%ANKI
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Basic
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What plumbing command is used in favor of manually editing symbolic reference files?
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Back: `symbolic-ref`
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454758074-->
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END%%
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%%ANKI
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Cloze
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Normal refs are to {`update-ref`} whereas symbolic refs are to {`symbolic-ref`}.
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454758076-->
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END%%
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%%ANKI
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Cloze
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The {`symbolic-ref`} plumbing command is used to manage {symbolic reference files}.
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454758077-->
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END%%
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%%ANKI
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Basic
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How do you correctly write the following command?
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```bash
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$ git symbolic-ref HEAD test
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```
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Back:
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```bash
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$ git symbolic-ref HEAD refs/heads/test
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```
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1710454758079-->
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END%%
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%%ANKI
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Cloze
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Branches are to {`refs/heads`} whereas remote branches are to {`refs/remotes`}.
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1711120782236-->
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END%%
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%%ANKI
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Basic
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What is the primary distinction between local branch refs and remotes?
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Back: The remotes are considered read-only.
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1711120782238-->
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END%%
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%%ANKI
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Basic
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What safeguard does git employ to keep remotes read-only?
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Back: It never updates `HEAD` to point to a remote ref.
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1711120782241-->
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END%%
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%%ANKI
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Basic
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What is prevented by git never updating `HEAD` to a remote ref?
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Back: One can't update the remote ref with a commit.
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Reference: Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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<!--ID: 1711120782244-->
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END%%
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## References
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* Scott Chacon, *Pro Git*, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014).
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