Git Commands Reference

Personal reference notes for git commands I frequently use

1. status

• untracked -> staged -> committed : (add .) -> (commit -m <MESSAGE>) -> (push)

2. log

• shows all commits and their hashes
• --no-pager, -n <NUM>
• --decorate=full|short|no
• --oneline
• --graph
• -p -> shows changes made in commit

3. cat-file -p <HASH>

• shows contents of the commit
• file -> blob, dir -> tree
• so if I want to see actual contents of a file, i need to provide blob hash

4. config

• --add <SECTION>.<KEY> <VALUE>
  • stored in .git/config
  • or I can use --global flag to be stored in $HOME/.gitconfig file
  • --get <SECTION>.<KEY>

[SECTION]
KEY = VALUE

• '--list' flag shows all stored section.key-value pairs

5. branch <NEW BRANCH NAME>

• branch is a pointer to a latest commit
• 'switch -c <NEW BRAMCH NAME>' will create new branch and checkout to it
• new branch starts from HEAD commit - if no commit, it will not diverge from its parent

6. merge <BRANCH NAME>

• merge <BRANCH NAME> to the branch you are currently on
• if branch tip diverged, new commit will be created then be merged (merge commit)
• if branch tip did not diverge, child branch will just merge into its parent (fast-forward merge)
• conflicts
  • whenever same file was changed from more than 2 different branches at the same time and tries to merge them, conflict occurs.
  • git shows the files that conflicts occured, marking <<< HEAD ===== >>> branch something like this
  • just deal with the conflicts then commit it again -> after committing it, branches will be merged automatically

7. rebase

• 'replays' previous commits on feature(or child) branch -> enables fast-forward merge
• think of this like moving feature branch tip to attach it after main branch tip
• I can use 'checkout [--ours | --theirs] <FILENAME>' to resolve conflict like I do in merge but keep in mind that [--ours | --theirs] might work differently than in merge
  • or I can manually fix the file myself
  • when resolving a conflict, I will be on new temporary branch
  • after resolving the conflict, 'git add .' then 'git rebase --continue'

8. undo changes

• going back to previous commits
• git reset --soft <COMMIT HASH>
  • soft reset -> go back to commit but keep the changes
  • --soft HEAD~1 -> go back 1 commit from HEAD
• git reset --hard <COMMIT HASH>
  • hard reset -> go back to commit and undo all changes
• commit --amend -> allow to change last commit

9. remote

• remote add <ORIGIN NAME> <URI>
• fetch -> copies .git/objects (metadata files)
• pull -> copying all files into local filesystem
• I can still manage remote branches
  • git log <REMOTE NAME>/<BRANCH NAME>
  • git merge <REMOTE NAME>/<BRANCH NAME>

10. fork (only for github)

- forking a repo is copying other people's repo into my account
- this is how contributing to other's projects
- fork -> new branch -> make changes -> make pull request to original repo

11. reflog

- HEAD = pointer to the last commit in current branch
- "reference log" -> tracks all the changes i made on 'HEAD' (? not clear : i see this command shows all the commits i made and history of manipulating branches)
- in case i accidentally deleted files +) get commit hash from the reflog -> use cat-file -p to recover deleted contents
- same case +) or i can use 'merge <commitish>' where commitish means hash for branches, reflog entries, commits, tags, ... (in this case i could use HEAD@{1}, if HEAD@{1} was deleted)

12. checkout