github_notes - RicoJia/notes GitHub Wiki

Resources:

Mando

Basic concepts

HEAD: where am I right now in the repo, or "the last commit in the current branch"
- detached head means: now HEAD is pointing to a commit, instead of a branch works for sub_directory as well.
  - In detached state, you can make experimental changes, without affecting any branches.
- good read

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Sample Workflows

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Pull Request, feature branch model

   - fork the repo on github.com
   - git clone the repo
   - git checkout -b NEW_BRANCH 
   - git add, git commit
    - ```git add``` doesn't add empty dirs
   - git push origin NEW_BRANCH   #you can see you've pushed to a new branch
   - comapre and make pull request, so in the pull request tab, you can see it. # the owner can merge 
#the pull request

Fix Bugs

  - git diff BRANCH1 BRANCH2
  - Then go to your branch, check out the <<<<< ==== >>>> marked lines, Edit them?
  - Add and commit
  - git checkout master
  - git merge some_branch --no-ff           #if no --no-ff, there will be no commits for pure addition. 
  - git branch -d devel 
  - git log --one line to simplify the output, see what commits there are

Undo undesired changes:

  # Before staging
  git stash							#temporarily store all changes somewhere else.
  or 
  git reset -- hard				    #Discard all local changes permanently

undo a commit: git revert <SHA>

if you hit git reset accidentally try git reflog
if develop is ahead, how to merge it into my branch? git checkout develop git pull #this only pulls from the same remote branch. git checkout feature git merge develop
Check changes you've made
```
 git checkout develop
 git pull
 git checkout FEATURE
 git diff develop FEATURE
```
- sometimes, after git checkout, you may see M, D... Those are uncommited changes from the last branch. You can still see them, but won't after you commit.
- If you see older branches, do git fetch -p
Request for review
- Make sure your commit is a draft
- Then, change it back to "ready for review"
- you can change it back any time: just go under the reviewers - convert to draft

git rebase and squashing

Scenario: once you're going to merge it into develop branch

Workflows

 	gitk or git	log --oneline #to find which commits to squash
 	git rebase -i HEAD~2  #this is to pull out the most recent 2 commits, so you can find the last two
 	# A file will come up, change the newer commit from "pick" to "squash", close the file
 #the newer one should be close to the bottom
 # This is because a remote repo is more likely to have the older version 
 	# Another file comes up, use # to commment out the old commit messages.

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Other common scenarios

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remove changes

git reset HEAD file (unstage staged but uncommited changes)
git checkout -- file (remove all unstaged changes made to a file)   # -- means to a file, VERY IMPORTANT
git restore --staged dir

git checkout BRANCH -- FILE_PATH: replace FILE_PATH on the current branch with the on BRANCH
-- File indicates what follows is a file

clone a branch, or tag

git clone a branch, git clone -b <branch_name> ...
clone a tag:
- You might find a version in tags. git clone -b <tag_name> --single-branch repo

Create a new branch from an exisiting branch

git checkout -b NEW_BRANCH branch2?

  git branch NEW_BRANCH     #so please do git branch -a, not git branch a
  git checkout NEW_BRANCH

rename a branch:

git branch -m <BRANCH_NAME>

Undo the last changes
- git reset --hard HEAD~1 remove the changes since last commit.
- git reset --soft HEAD~1 (or SHA1) -- still keeps the changes. but as unstaged
- git revert (TODO) ,adds the unstaged changes as a new commit? (yes, but found some changes were not undone. Need further investigation)

discard local changes

git stash save --keep-index --include-untracked
git stash drop

Go back to a previous commit, test.

git checkout COMMIT_SHA1  // don't include ., else you will not enter a "detached state", and anything you do WILL be saved as a last commit
#do tests

then come back without having any changes,

  # don't commit anything
  git checkout BRANCH_NAME

If you want to keep the changes, then make a branch
```
git checkout -b NEW_BRANCH
```

Start a new account:
- Follow the github page steps closely, add your personal ssh

reset a url
- git remote add NAME URL
- E.g, git remote add origin [email protected]:ME495-EmbeddedSystems/homework-2-RicoJia.git
- Use SSH instead of HTTPs so you always automatically push

delete a branch

git push origin --delete BRANCH_NAME Delete a branch remotely
git branch -d BRANCH to locally delete branch, if not committed, fails
git branch -D BRANCH to locally delete branch force

list all files

git ls-tree -r master --name-only

see config, git config:
- git config --global user.name "name"
- git config --global user.email "email"
- Technically, you can remap commands
```
git config --global alias.st status #Remap status to st
```
git cherry-pick SHA: 将一个commit 直接移植过来。(only the commit, nothing else)

insert a commit before a previous one:

git checkout -b temp PREVIOUS_COMMIT
git commit 
git rebase temp develop
#fix some conflicts
git add files_changed
git rebase --continue

Scenario: you want to update your branch from another branch:
```
git pull origin FEATURE 
```
- if pulling doesn't solve the problem, maybe you're change is already ahead of the branch!!
Scenario: files exist on another branch, and you want to get them here
```
git checkout FEATURE -- FILENAME
```

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Update Repo

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git fetch + git merge allows you to choose which branch of local repo you want to update.
- conflict: two person changing the same lines.
  - Make sure you remove all the conflict markers <<<<<<, else there will be problems.
- git fetch
  - Get update from remote to local branch, including all commits, but this doesn't update anything
git merge
1. git merge
  - will merge try to merge the newest local commit, and the newest remote commit, and you gotta solve merging conflicts. Then, a new commit is created
  - go to the main branch, then merge feature branch into it $git checkout develop $ git merge feature
2. git mergetool is a good tool to see merge conflicts.
3. Merge two remote branches: ```bash git clone repo.git #you can download only one branch?? Well, check git branch -a to see all your options!! git checkout destination_branch #(could be a remote one, like origin/something, but just type the name after origin) git pull --allow_unrelated_histories repo.git branch_name commit all changes and push
```
4. ```git merge -no-ff BRANCH```
- ```no-ff``` is no fast forward: if BRANCH is a newer branch, then instead of bring head to BRANCH, you go one step further and create a new commit on top of it
```

git stash Should there be a merging conflict,

git stash: after git stash pop, you might get conflicts. to solve it, do git add
More comprehensively,

  git stash                                       #save your work aside for working on higher priority tasks. make sure everything is commited or stashed
  git stash list                                  #check out a list of stashes, what is stashed from which branch. 
  # you can see the stashes, then apply it. 
  git stash apply stash@{0}                       #you can save the changes back to your branch. Note: this step does not remove the stash
  git stash drop stash${1}                                   #to  dump stash here.
  git merge branchB                               #on branch B, merging branch A

git stash show, see files in most recent stash
git stash show -p see diff
git stash save -m "msg" just like git stash

git pull pull all branches
- git pull origin BRANCH
- git push is equivalent to git fetch REMOTE + git merge
  - You can also git pull --rebase, which shoves the local commits right after the remote commits. rebase is good for keeping a linear history
  - But now I prefer
```
 	git checkout develop
 	git pull 
 	git checkout feature
 	git rebase develop
 	#solve conflict
```
git push
- git push -u: -u is to make sure the branch on the remote host will be tracked, so git pull will work seamlessly.
- git push origin --delete name, delete remote branch
git add:

  git add . is dangerous
  git add -p file  # you can incrementally add files

- git has a "buffer" called stage, which is the main difference from SVN. git add is "staging"
- git commit -am "": a is to add all tracked files to stage.
- Stage the new file. nothing being added right now but it's telling git that it's going to add something for commit
- ```git add -A```: **stage all files/deleted files, better than git add.**

git commit -m "message"
- commit with a message. BE SURE IT's IN YOUR BRANCH!!
Git Submodules - This has bee n a pain
- git clone recursive clones the module and all submodules
- Add git submodules:
```
# 1 go to destination folder
# 2. do this directly 
git submodule add <remote_url>
# 3. see list of submodules
git submodule--helper list
# VERY IMPORTANT:
git add & git commit
```
- update/download submodules: git submodule update --init --recursive
  - branch might have been switched
- Tricky situation:
  1. say you are in ~/non_git_repo, and you have~/non_git_repo/git_repo
  - if you have ~/non_git_repo/git_repo/bash_file that does git submodule update --init --recursive
  - do ./git_repo/bash_file will fail, because you can't run git submodule in a non-git root
  1. How to remove a submodule
```
Delete the relevant section from the .gitmodules file.
Stage the .gitmodules changes git add .gitmodules
Delete the relevant section from .git/config. This caches the older submodule HEAD
Run git rm --cached path_to_submodule (no trailing slash).
Run rm -rf .git/modules/path_to_submodule (no trailing slash).
Commit git commit -m "Removed submodule "
Delete the now untracked submodule files rm -rf path_to_submodule
```
    - When you test, If you have submodule inside a submodule
      - you must make sure you are on the right branch in every repo. Otherwise, you might see
        fatal: remote error: upload-pack: not our ref 578dd0a0ac8fe1104e9cafee6f6670d4561baddc
      - that means the cached submodule in ~/root/.git/config has been removed, but your submodule has not been updated. So delete your submodules and start over
        fatal: 'git status --porcelain=2' failed in submodule nonros/scheduler
- git submodule sync
  1. submodule host url changes
  2. update local .gitmodules for the url
  3. run git submodule sync to update the local configs
To download a concrete branch, first git checkout -b, then git pull

Status & Diff

git status
- check out files that are added. It will show which
git diff
- See differences you have made.
  - git diff BRANCH1 BRANCH2 Compare two branches
- git diff of a certain path git diff develop feature PATH
- git diff ignoring white space git diff -w develop feature
- checking diff between current commit and last commit git diff HEAD^ HEAD, ^ means one prior commit
- git diff file: see what's changed
- git --no-pager diff --name-status origin/develop will show on the screen what pkgs have been changed
git log : show commit history
- git log --format="%aN" -- FILE_NAME shows the authors of a FILE_NAME
git show FILE_NAME: show the file content; git show just shows files changed from the previous commits!!

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Branching and Tagging

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git branch
1. git branch -a
  - check all existing branches in your repo directory;
  - * means current branch; HEAD is the pointer pointing to your current branch
2. git branch -d branch_name
  - deletes a local branch
3. git branch -m rico/Refactored_REST_endpoint, change name of branch
git tag: a pointer pointing to a commit 2. git tag v1.0 create a new tag - git tag v0.9 f52c633 create a new tag on this commit - git tag -a v0.1 -m "version 0.1 released" 1094adb add some msg 3. git tag to see all tags - git show TAG: see the tag commit info 4. git tag -d v0.1 delete tag - git push origin :refs/tags/v0.1 delete a remote tag, you don't have to delete the local tag 5. git push origin v0.1 push this tag to the remote machine - git push origin --tags push all tags - git push origin v0.1: so you can push a tag successfully

Jimmy's Github Rules

Create a branch off of develop
- rico/JIRA_ID_name
- You can have multiple PRs under the same JIRA Ticket
Github User name is First name + Last name
- CHANGES.txt is generated this way
Mark your PR as draft
Make sure your tests have been passed! on ocean_builds
Add tests if you add a new feature
Do not run git add .
- git commit -am "" Don't use that, use git commit -m
Do not check in temp files. Use .gitignore for that
Post on ocean_pr, even for comments addressed.
Github Best Practices
- PR should not live > 1 wk.
- First work on your own branch. When you're close to finishing it, open a draft PR.
- [QA-529] some fixes ... (informative title)
- post a link to the Channel once code ready for review
- Delete your branch

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Misc

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How to write .gitignore?
- * matches any char in file name, ** matches dirs before it
- if you want to exclude a file in the current directory: /CMakeLists.txt
- or a directory: /dist . / means directory, and is relative to where .gitignore resides.
- git ignore
```
*.class

# 不排除.gitignore和App.class:
!.gitignore   #so you can't do git add -f
!App.class
```
- git add -f App.class override gitignore
Continuous Integration and Continuous Delivery
- Continuous Integration
  - When you have a conflict, you want to find it quickly, even if they're in the feature branches.
  - CI will continuously build their versions(?), test the build (the tests are stored in a different locations) (What test?), and and Inform them (?)
a bare git repo has only .git, with head, config, etc. mirror push to your own repo: git push --mirror https://github.com/<your_github_handle>/lab-exercises.git
- Question: can you use ssh instead of https?
semantic versioning: V 0.1.2 - the first major version, with 1st generation features, and 2 bug fixes
if you see insufficient permission for adding an object, go change the file permission
Github.io:
1. website: go to the root directory with "_site" directory, first jekyll build, then jekyll serve
adding another account on your computer
git bisect to find the bad commit that was causing trouble
1. git bisect bad HEAD -> git bisect good <KNOWN_GOOD_COMMIT>
2. Then git will jump to the middle commit
3. Keep doing this, until we hit the bad apple
4. git bisect reset. when you're done to jump back to HEAD

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Gitlab

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Mirrored repos from github
- Create, force update
Show markdown
- either do $`a^2+b^2`$, or do:
```
    ```math
      a^2 + b^2
    ```
```

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References

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render latex:
- Render it, and copy the url from a drop down menu

github_notes - RicoJia/notes GitHub Wiki

Basic concepts

Sample Workflows

Other common scenarios

Update Repo

Status & Diff

Branching and Tagging

Jimmy's Github Rules

Misc

Gitlab

References

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