git tricks (part I)

git tricks (part I)

• under the hood
  • trees, references, commits, branches, merging
• git hacks
• gitdown demo

under the hood

git init

git init demo

git repository

• a simple key value data store that stores:
  • blobs, which are the most basic data type in Git. A blob is just a bunch of bytes; usually a binary representation of a file.
  • tree objects, which are a bit like directories. Tree objects can contain pointers to blobs and other tree objects.
  • commit objects, which point to a single tree object, and contain some metadata including the commit author and any parent commits.
  • references, which are pointers to a single object (usually a commit or tag object).

.git/

• .git/objects

• .git/refs

tree objects

• can be thought of as a directory
• contains a list of blobs (files) and other tree objects (sub-directories).

tree objects

README
src/
    hello.c

tree objects

commits

commit

• a pointer that contains a few pieces of important metadata.
• the commit itself has a hash, which is built from the metadata that it contains:
  • the hash of the tree at the time of commit
  • the hash of parent commits
  • author's info
  • committer's info
  • commit message

commit demo

references

references

• .git/refs

• a file stored somewhere in .git/refs, containing the hash of a commit object.

references demo

branches

branches

branches are references

branches demo

merging

merging

the process of joining two branches together

merging demo

merging

back to demo

merging

back to demo

merging

git hacks

undoing things

• Update a commit message

  • git commit --amend

• Undo local changes

  • git reset / checkout

• Undo pushed changes

  • git reset + git push --force

• Undo last n commits

  • git reset HEAD~n 

• Undo part of a commit 

  • git revert --no-commit

• UNDO ANYTHING

  • git reflog + git checkout

branch diff

git show-branch

commit parts of a file

git add --patch

aliases

https://github.com/robbyrussell/oh-my-zsh/blob/master/plugins/git/git.plugin.zsh

prettify git

• Configure colors to your .gitconfig
  • https://gist.github.com/rab/4067067
• Better git log

what are your favorite git hacks?

gitdown demo

next time?

• git features
  • rebasing, cherry picking, tags
• git commands
  • stash, bisect, fsck