# Git
🔹 *parent* [[⧋ Programming|Programming]]
▫️ *related* [[Git cheat sheet]], [[⏶ Github|Github]], [[✦ Git Essential Training|Git Essential Training]]
## Tasks:
- [ ] Read more about the head pointer/current pointer
- [ ] Read more about SHA-1 - not necessary, but helps explain how it comes up with IDs
- [ ] Read more about atomic commits
- [ ] Lookup more about `git checkout -- <file_name>`
- [ ] Finish all of the skipped sections
- [ ] Watch all of [git branches, merges, and remotes](https://www.linkedin.com/learning/git-branches-merges-and-remotes/branching-overview?u=2106729)
- [ ] Configure command prompt for zsh again. Previously did this but I'm not sure exactly how it's configured
---
## Cheatsheet
## Notes:
find ID and name of who commited
### Navigate the Commit Tree
### Reference commits
SHA-1 Hash - 40 character string
Sha - 8 chracters at end, or Head Pointer
.git/HEAD - where it searches first
.git/refs/heads/master - has SHA that points to current head
Finding current head information:
git show de14
git show HEAD
These will find the parent of each branch, you can find the grandparents with ^^
```bash
de14621f^
HEAD^
master^
```
Also this will find the great grandparent branch, number says how many levels up it should go.
```bash
HEAD~3
```
##### Tree listings
gives directory list of head
```
git ls-tree HEAD
```
pattern matches to find anything with "assets" in directory HEAD
```
git ls-head HEAD assets
```
##### Filter and Format the commit log
returns the last three commits
git log -3
returns everything before the day listed in yyyy-mm-dd format:
```bash
git log --since=2019-01-01
```
returns all commits until the day listed
```bash
git log --until=2019-01-01
```
Other formats:
```bash
git log --until="3 days ago"
git log --after=2.weeks --before=3.days
```
shows only commits that have changed one file in a directory:
```bash
git log explorers.html
```
Show statistics about what was changed
```bash
git log --stat
```
##### git logs
```bash
git log
```
```bash
git help log
```
```bash
git log --since=2020-01-01
```
```bash
git log --until=2020-01-01
```
### Branching
##### Staging commits and pushing to remote branch
Adds to staging tree
```bash
git add -A
```
Adds commit
```bash
git commit -m 'this is the commit message'
```
Pushes to remote repository
```bash
git push
```
The head pointer - current pointer - look up more on that.
SHA-1
cat .git/refs/heads/master
git log
Tells you the difference - like untracked files - it will show staged and unstaged - if somethng has been commited, it will just say "working clean tree".
```bash
git status
```
Shows all differences
```bash
git diff
```
Shows differences between staged files
```bash
git diff --staged
```
Similar but older way to do above command
```bash
git diff --cached
```
Delete a specific file - need to have the correct relative path
```bash
git rm file_to_delete.txt
```
If a file is the same content but the name is changed and they're both in the staging area, git will know that is probably just a renamed file. With `git status` it will list it as:
```git
renamed: one_file.txt -> renamed_file.txt`
```
### Reset Branches
##### Reset types
Soft reset:
- Moves HEAD Pointer
- Does not change staging index
- Does not change working directory
Uses:
- Return to an old state and leave code changes staged
- Useful for amending one or more commits
- Similar to `git commit --amend`
- Previous commits will be discarded
- Be careful about amending commits which have been shared
```bash
git reset --soft <tree-ish>
```
Mixed reset
- Moves HEAD pointer
- Changes staging index to match repository
- Does not change working directory
- This is the default reset if soft or hard is not specified
```bash
git reset --mixed <tree-ish>
```
Hard Reset:
- Moves HEAD pointer
- Changes staging index to match repository
- Changes working directory to match repository
```bash
git reset --hard <tree-ish>
```
### Atomic commits
`Git add` + `git commit -m` will just commit those files you've added (new and previously tracked), but `git commit -am` will commit all changes on tracked files, but it doesn't add new files.
```git
git commit -am 'message'
```
### Undo changes
To checkout only one file from the master and apply it to current branch, you can then compare the two (somehow, lookup).
```
git checkout -- <file_name>
```
Find the commit ID
```
git log
```
Grab the id of the previous commit and check out a specific tracked file:
```
git checkout d4450dc7fa7 -- explorers.html
```
Then git status see the difference
```
git status
```
Show the differences between
git diff --staged
git checkout
### Revert a commit
git show \[id\]
## Questions
- I feel like the Git Lens plugin on VS code is a lot easier to use than git status
- it's good to know how to use git status, but Git Lens is just cleaner
## References
git notes from Evernote [Evernote](https://www.evernote.com/l/ARJJqYI3JpdDTqWNLssjo5SJkzV6U-T42hE)
LinkedIn Learning, [course](https://www.linkedin.com/learning/git-essential-training-the-basics/)