# git

* [https://git-scm.com/](https://git-scm.com/)

### Notes:

Migrate Master to Main 

```bash
git branch -m master main
gpom ( git push origin main )
git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/main
git push origin --delete master
git push code --delete master

```

Sparse checkout
* [https://github.blog/2020-01-17-bring-your-monorepo-down-to-size-with-sparse-checkout/](https://github.blog/2020-01-17-bring-your-monorepo-down-to-size-with-sparse-checkout/)
```sh
git init
git remote add origin <url>
git config core.sparseCheckout true
echo "app" >> .git/info/sparse-checkout
git pull origin master
git checkout tags/v1.0
```

removing commit history of file   
[https://help.github.com/en/github/authenticating-to-github/removing-sensitive-data-from-a-repository](https://help.github.com/en/github/authenticating-to-github/removing-sensitive-data-from-a-repository)
```sh
git filter-branch --force --index-filter \
  "git rm --cached --ignore-unmatch PATH-TO-YOUR-FILE-WITH-SENSITIVE-DATA" \ --prune-empty --tag-name-filter cat -- --all
git push origin --force --all
```

## Setup

##### Show current configuration:
```
$ git config --list
```
##### Show repository configuration:
```
$ git config --local --list
```

##### Show global configuration:
```
$ git config --global --list
```

##### Show system configuration:
```
$ git config --system --list
```

##### Set a name that is identifiable for credit when review version history:
```
$ git config --global user.name “[firstname lastname]”
```

##### Set an email address that will be associated with each history marker:
```
$ git config --global user.email “[valid-email]”
```

##### Set automatic command line coloring for Git for easy reviewing:
```
$ git config --global color.ui auto
```

##### Set global editor for commit
```
$ git config --global core.editor vi
```

<hr/>

## Configuration Files

##### Repository specific configuration file [--local]:
```
<repo>/.git/config
```

##### User-specific configuration file [--global]:
```
~/.gitconfig
```

##### System-wide configuration file [--system]:
```
/etc/gitconfig
```

<hr/>

## Create

##### Clone an existing repository:

There are two ways:

Via SSH

```
$ git clone ssh://user@domain.com/repo.git
```

Via HTTP

```
$ git clone http://domain.com/user/repo.git
```

##### Create a new local repository:
```
$ git init
```
<hr/>
## Local Changes

##### Changes in working directory:
```
$ git status
```

##### Changes to tracked files:
```
$ git diff
```

##### Add all current changes to the next commit:
```
$ git add .
```

##### Add some changes in &lt;file&gt; to the next commit:
```
$ git add -p <file>
```

##### Commit all local changes in tracked files:
```
$ git commit -a
```

##### Commit previously staged changes:
```
$ git commit
```

##### Commit with message:
```
$ git commit -m 'message here'
```

##### Commit skipping the staging area and adding message:
```
$ git commit -am 'message here'
```

##### Commit to some previous date:
```
$ git commit --date="`date --date='n day ago'`" -am "<Commit Message Here>"
```

##### Change last commit:<br/>
<em><sub>Don't amend published commits!</sub></em>

```
$ git commit -a --amend
```

##### Amend with last commit but use the previous commit log message
<em><sub>Don't amend published commits!</sub></em>

```shell
$ git commit --amend --no-edit
```

##### Change committer date of last commit:
```
GIT_COMMITTER_DATE="date" git commit --amend
```

##### Change Author date of last commit:
```shell
$ git commit --amend --date="date"
```

##### Move uncommitted changes from current branch to some other branch:<br/>
```
$ git stash
$ git checkout branch2
$ git stash pop
```

##### Restore stashed changes back to current branch:
```shell
$ git stash apply
```

#### Restore particular stash back to current branch:
```shell
- *{stash_number}* can be obtained from `git stash list`


$ git stash apply stash@{stash_number}
```

##### Remove the last set of stashed changes:
```
$ git stash drop
```

<hr/>

## Search

##### A text search on all files in the directory:
```
$ git grep "Hello"
```

##### In any version of a text search:
```
$ git grep "Hello" v2.5
```

<hr/>

## Commit History

##### Show all commits, starting with newest (it'll show the hash, author information, date of commit and title of the commit):
```
$ git log
```

##### Show all the commits(it'll show just the commit hash and the commit message):
```
$ git log --oneline
```

##### Show all commits of a specific user:
```
$ git log --author="username"
```

##### Show changes over time for a specific file:
```
$ git log -p <file>
```

##### Display commits that are present only in remote/branch in right side
```
$ git log --oneline <origin/master>..<remote/master> --left-right
```

##### Who changed, what and when in &lt;file&gt;:
```
$ git blame <file>
```

##### Show Reference log:
```
$ git reflog show
```

##### Delete Reference log:
```
$ git reflog delete
```
<hr/>

## Branches & Tags

##### List all local branches:
```
$ git branch
```

#### List local/remote branches
```
$ git branch -a
```

##### List all remote branches:
```
$ git branch -r
```

##### Switch HEAD branch:
```
$ git checkout <branch>
```

##### Checkout single file from different branch
```
$ git checkout <branch> -- <filename>
```

##### Create and switch new branch:
```
$ git checkout -b <branch>
```

#### Checkout and create a new branch from existing commit
```
$ git checkout <commit-hash> -b <new_branch_name>
```

##### Create a new branch based on your current HEAD:
```
$ git branch <new-branch>
```

##### Create a new tracking branch based on a remote branch:
```
$ git branch --track <new-branch> <remote-branch>
```

##### Delete a local branch:
```
$ git branch -d <branch>
```

##### Rename current branch to new branch name
```shell
$ git branch -m <new_branch_name>
```

##### Force delete a local branch:
<em><sub>You will lose unmerged changes!</sub></em>

```
$ git branch -D <branch>
```

##### Mark the current commit with a tag:
```
$ git tag <tag-name>
```

##### Mark the current commit with a tag that includes a message:
```
$ git tag -a <tag-name>
```
<hr/>

## Update & Publish

##### List all current configured remotes:
```
$ git remote -v
```

##### Show information about a remote:
```
$ git remote show <remote>
```

##### Add new remote repository, named &lt;remote&gt;:
```
$ git remote add <remote> <url>
```

##### Download all changes from &lt;remote&gt;, but don't integrate into HEAD:
```
$ git fetch <remote>
```

##### Download changes and directly merge/integrate into HEAD:
```
$ git remote pull <remote> <url>
```

##### Get all changes from HEAD to local repository:
```
$ git pull origin master
```

##### Get all changes from HEAD to local repository without a merge:
```
$ git pull --rebase <remote> <branch>
```

##### Publish local changes on a remote:
```
$ git push remote <remote> <branch>
```

##### Delete a branch on the remote:
```
$ git push <remote> :<branch> (since Git v1.5.0)
```
OR
```
$ git push <remote> --delete <branch> (since Git v1.7.0)
```

##### Publish your tags:
```
$ git push --tags
```
<hr/>

#### Configure the merge tool globally to meld (editor)
```bash
$ git config --global merge.tool meld
```

##### Use your configured merge tool to solve conflicts:
```
$ git mergetool
```

## Merge & Rebase

##### Merge branch into your current HEAD:
```
$ git merge <branch>
```

##### Rebase your current HEAD onto &lt;branch&gt;:<br/>
<em><sub>Don't rebase published commit!</sub></em>

```
$ git rebase <branch>
```

##### Abort a rebase:
```
$ git rebase --abort
```

##### Continue a rebase after resolving conflicts:
```
$ git rebase --continue
```

##### Use your editor to manually solve conflicts and (after resolving) mark file as resolved:
```
$ git add <resolved-file>
```

```
$ git rm <resolved-file>
```

##### Squashing commits:
```
$ git rebase -i <commit-just-before-first>
```

Now replace this,

```
pick <commit_id>
pick <commit_id2>
pick <commit_id3>
```

to this,

```
pick <commit_id>
squash <commit_id2>
squash <commit_id3>
```
<hr/>

## Undo

##### Discard all local changes in your working directory:
```
$ git reset --hard HEAD
```

##### Get all the files out of the staging area(i.e. undo the last `git add`):
```
$ git reset HEAD
```

##### Discard local changes in a specific file:
```
$ git checkout HEAD <file>
```

##### Revert a commit (by producing a new commit with contrary changes):
```
$ git revert <commit>
```

##### Reset your HEAD pointer to a previous commit and discard all changes since then:
```
$ git reset --hard <commit>
```

##### Reset your HEAD pointer to a remote branch current state.
```
$ git reset --hard <remote/branch> e.g., upstream/master, origin/my-feature
```

##### Reset your HEAD pointer to a previous commit and preserve all changes as unstaged changes:
```
$ git reset <commit>
```

##### Reset your HEAD pointer to a previous commit and preserve uncommitted local changes:
```
$ git reset --keep <commit>
```

##### Remove files that were accidentally committed before they were added to .gitignore
```
$ git rm -r --cached .
$ git add .
$ git commit -m "remove xyz file"
```
<hr/>

## Git-Flow
Improved [Git-flow](https://github.com/petervanderdoes/gitflow-avh)


<hr/>

### Setup
###### You need a working git installation as prerequisite. Git flow works on OSX, Linux and Windows.

##### OSX Homebrew:
```
$ brew install git-flow-avh
```

##### OSX Macports:
```
$ port install git-flow
```

##### Linux (Debian-based):
```
$ sudo apt-get install git-flow
```

##### Windows (Cygwin):
###### You need wget and util-linux to install git-flow.
```bash
$ wget -q -O - --no-check-certificate https://raw.githubusercontent.com/petervanderdoes/gitflow/develop/contrib/gitflow-installer.sh install <state> | bash
```
<hr/>

### Getting Started
###### Git flow needs to be initialized in order to customize your project setup. Start using git-flow by initializing it inside an existing git repository:
##### Initialize:
###### You'll have to answer a few questions regarding the naming conventions for your branches. It's recommended to use the default values.
```shell
git flow init
```
OR
###### To use default
```shell
git flow init -d
```
<hr/>

### Features
###### Develop new features for upcoming releases. Typically exist in developers repos only.
##### Start a new feature:
###### This action creates a new feature branch based on 'develop' and switches to it.
```
git flow feature start MYFEATURE
```

##### Finish up a feature:
###### Finish the development of a feature. This action performs the following:
###### 1) Merged MYFEATURE into 'develop'.
###### 2) Removes the feature branch.
###### 3) Switches back to 'develop' branch
```
git flow feature finish MYFEATURE
```

##### Publish a feature:
###### Are you developing a feature in collaboration? Publish a feature to the remote server so it can be used by other users.
```
git flow feature publish MYFEATURE
```

##### Getting a published feature:
###### Get a feature published by another user.
```
git flow feature pull origin MYFEATURE
```

##### Tracking a origin feature:
###### You can track a feature on origin by using
```
git flow feature track MYFEATURE
```
<hr/>

### Make a Release
###### Support preparation of a new production release. Allow for minor bug fixes and preparing meta-data for a release

##### Start a release:
###### To start a release, use the git flow release command. It creates a release branch created from the 'develop' branch. You can optionally supply a [BASE] commit sha-1 hash to start the release from. The commit must be on the 'develop' branch.
```
git flow release start RELEASE [BASE]
```
###### It's wise to publish the release branch after creating it to allow release commits by other developers. Do it similar to feature publishing with the command:
```
git flow release publish RELEASE
```
###### (You can track a remote release with the: ```git flow release track RELEASE``` command)

##### Finish up a release:
###### Finishing a release is one of the big steps in git branching. It performs several actions:
###### 1) Merges the release branch back into 'master'
###### 2) Tags the release with its name
###### 3) Back-merges the release into 'develop'
###### 4) Removes the release branch
```
git flow release finish RELEASE
```
###### Don't forget to push your tags with ```git push --tags```

<hr/>

### Hotfixes
###### Hotfixes arise from the necessity to act immediately upon an undesired state of a live production version. May be branched off from the corresponding tag on the master branch that marks the production version.

##### Git flow hotfix start:
###### Like the other git flow commands, a hotfix is started with
```
$ git flow hotfix start VERSION [BASENAME]
```
###### The version argument hereby marks the new hotfix release name. Optionally you can specify a basename to start from.

##### Finish a hotfix:
###### By finishing a hotfix it gets merged back into develop and master. Additionally the master merge is tagged with the hotfix version
```
git flow hotfix finish VERSION
```
<hr/>