Code-Management/Git/main.md

@@ -1,215 +1,523 @@
-# Git Commands Guide
+# Git Commands Guide (DevOps-Oriented)
 
 ## 1. Installation and Setup
 
 ### Install Git
-Download from [git-scm.com](https://git-scm.com/).
+
+Download and install Git from:
+[https://git-scm.com/](https://git-scm.com/)
+
+Linux (Debian/Ubuntu):
+
+```bash
+sudo apt update && sudo apt install git -y
+```
+
+RHEL/CentOS:
+
+```bash
+sudo yum install git -y
+```
+
+macOS (Homebrew):
+
+```bash
+brew install git
+```
 
 ### Verify Installation
+
 ```bash
 git --version
 ```
 
-### Configure User Info
-Set your name and email for commits:
+### Configure User Identity
+
+Git uses this information for commits:
+
 ```bash
 git config --global user.name "Your Name"
 git config --global user.email "your.email@example.com"
 ```
 
+Check configuration:
+
+```bash
+git config --list
+```
+
+Configuration scopes:
+
+* `--system`: All users
+* `--global`: Current user
+* `--local`: Repository only
+
+---
+
 ## 2. SSH Key Configuration
 
-Use a custom SSH key:
+### Generate SSH Key
+
 ```bash
-git config --add --local core.sshCommand 'ssh -i <PATH_TO_SSH_KEY>'
+ssh-keygen -t ed25519 -C "your.email@example.com"
 ```
 
-Clone with custom key:
+Start SSH agent and add key:
+
 ```bash
-git -c core.sshCommand="ssh -i <key-path>" clone host:repo
+eval "$(ssh-agent -s)"
+ssh-add ~/.ssh/id_ed25519
 ```
 
+### Use Custom SSH Key (Per Repository)
+
+```bash
+git config --local core.sshCommand "ssh -i <PATH_TO_SSH_KEY>"
+```
+
+Clone with custom SSH key:
+
+```bash
+git -c core.sshCommand="ssh -i <key-path>" clone git@host:repo.git
+```
+
+---
+
 ## 3. Initialize Repository
 
-Create a new Git repo:
+Create a new Git repository:
+
 ```bash
 git init -b main
 ```
-- `-b main`: Sets default branch name to `main`.
+
+Existing repository:
+
+```bash
+git init
+```
+
+---
 
 ## 4. Basic Workflow
 
-### Stage and Commit
+### Stage and Commit Changes
+
 Stage all changes:
+
 ```bash
 git add -A
 ```
+
 Commit changes:
+
 ```bash
-git commit -m "Initial Commit"
+git commit -m "Initial commit"
 ```
 
-### Connect to Remote
-Link local repo to remote:
+### Connect Local Repository to Remote
+
 ```bash
-git remote add origin <Repo-Link>
+git remote add origin <REPO_URL>
+```
+
+Verify:
+
+```bash
+git remote -v
 ```
 
 ### Push to Remote
+
+First push:
+
 ```bash
-git push origin main
+git push -u origin main
 ```
 
+Subsequent pushes:
+
+```bash
+git push
+```
+
+---
+
 ## 5. Repository Status and History
 
-### Check Status
+### Check Repository Status
+
 ```bash
 git status
 ```
-Shows staged, unstaged, and untracked files.
 
-### View History
+### View Commit History
+
 ```bash
 git log
 ```
-- `git log -p`: Shows diffs per commit.
-- `git log -3`: Shows last 3 commits.
-- `git log --graph`: Shows history as a graph.
-- `git log --oneline`: Shows compact log.
 
-### View Changes
+Common options:
+
+```bash
+git log --oneline
+git log --graph --oneline --all
+git log -p
+git log -3
+```
+
+### View File Changes
+
+Unstaged changes:
+
 ```bash
 git diff
 ```
-Shows unstaged changes.
+
+Staged changes:
 
 ```bash
 git diff --staged
 ```
-Shows staged changes.
+
+Compare branches:
+
+```bash
+git diff main..dev
+```
+
+---
 
 ## 6. File Operations
 
 ### Stage Specific Files
+
 ```bash
-git add <filename>
+git add <file>
 ```
 
 ### Unstage Files
+
 ```bash
-git reset <filename>
+git reset <file>
 ```
 
-### Discard Changes
+### Discard Local Changes
+
 ```bash
-git checkout -- <filename>
+git checkout -- <file>
+```
+
+Restore using modern command:
+
+```bash
+git restore <file>
 ```
-Reverts file to last committed state.
 
 ### Rename File
+
 ```bash
-git mv <old-name> <new-name>
+git mv old-name new-name
 ```
 
 ### Remove File
+
 ```bash
-git rm <filename>
+git rm <file>
 ```
 
+Remove but keep locally:
+
+```bash
+git rm --cached <file>
+```
+
+---
+
 ## 7. Branch Management
 
-### Create and Switch to Branch
+### Create and Switch Branch
+
 ```bash
 git checkout -b <branch-name>
 ```
 
+Modern alternative:
+
+```bash
+git switch -c <branch-name>
+```
+
 ### List Branches
+
 ```bash
 git branch
-```
-List with details:
-```bash
+git branch -a
 git branch -v
 ```
 
 ### Delete Branch
+
 ```bash
 git branch -d <branch-name>
 ```
 
-### Switch Branch
+Force delete:
+
 ```bash
-git checkout <branch-name>
+git branch -D <branch-name>
 ```
 
-## 8. Merging
+### Rename Branch
+
+```bash
+git branch -m old-name new-name
+```
+
+---
+
+## 8. Merging and Rebasing
 
 ### Merge Branch
+
 ```bash
 git merge <branch-name>
 ```
 
-**Merge Types:**
-- **Fast-forward:** No conflicts; branch is ahead of target.
-- **Three-way:** Conflicts possible; creates new merge commit.
+Merge types:
+
+* Fast-forward
+* Three-way merge (creates merge commit)
+
+### Rebase (Linear History)
+
+```bash
+git rebase main
+```
+
+Abort rebase:
+
+```bash
+git rebase --abort
+```
+
+Continue rebase:
+
+```bash
+git rebase --continue
+```
+
+---
 
 ## 9. Remote Operations
 
 ### List Remotes
+
 ```bash
 git remote
-```
-
-### Show Remote Info
-```bash
 git remote -v
 ```
+
+### Show Remote Details
+
 ```bash
 git remote show origin
 ```
 
 ### Fetch Changes
-```bash
-git fetch
-```
-Get updates without merging.
 
 ```bash
+git fetch
 git fetch --all
 ```
-Fetch from all remotes.
+
+### Pull Changes
+
+Fetch + merge:
+
+```bash
+git pull
+```
+
+Rebase instead of merge:
+
+```bash
+git pull --rebase
+```
+
+---
 
 ## 10. Commit Management
 
-### Edit Last Commit Message
+### Amend Last Commit
+
 ```bash
 git commit --amend
 ```
 
-### Show Commit Changes
+### Show Commit Details
+
 ```bash
 git show <commit-id>
 ```
 
-### Revert Commit
-```bash
-git revert HEAD
-```
-Revert last commit.
+### Revert Commit (Safe for Shared Branches)
 
 ```bash
 git revert <commit-id>
 ```
-Revert specific commit.
 
-## 11. Miscellaneous
+### Reset Commit (Use with Caution)
+
+Soft reset:
+
+```bash
+git reset --soft HEAD~1
+```
+
+Mixed reset:
+
+```bash
+git reset HEAD~1
+```
+
+Hard reset:
+
+```bash
+git reset --hard HEAD~1
+```
+
+---
+
+## 11. Stash (Temporary Changes)
+
+Save work without committing:
+
+```bash
+git stash
+```
+
+List stashes:
+
+```bash
+git stash list
+```
+
+Apply stash:
+
+```bash
+git stash apply
+```
+
+Pop stash:
+
+```bash
+git stash pop
+```
+
+---
+
+## 12. Tags (Releases)
+
+Create tag:
+
+```bash
+git tag v1.0.0
+```
+
+Annotated tag:
+
+```bash
+git tag -a v1.0.0 -m "Release v1.0.0"
+```
+
+Push tags:
+
+```bash
+git push origin --tags
+```
+
+---
+
+## 13. .gitignore
+
+Create `.gitignore`:
+
+```bash
+touch .gitignore
+```
+
+Example:
+
+```
+.env
+node_modules/
+*.log
+```
+
+Apply after commit:
+
+```bash
+git rm -r --cached .
+git add .
+git commit -m "Apply gitignore"
+```
+
+---
+
+## 14. Useful Configuration and Aliases
+
+Change default editor:
 
-### Change Default Editor
 ```bash
 git config --global core.editor "vim"
 ```
 
-### Clone Repository
+Create aliases:
+
 ```bash
-git clone <Repo-Link>
+git config --global alias.st status
+git config --global alias.co checkout
+git config --global alias.cm commit
+git config --global alias.br branch
 ```
+
+---
+
+## 15. Troubleshooting and Recovery
+
+Undo last commit but keep changes:
+
+```bash
+git reset --soft HEAD~1
+```
+
+Recover deleted branch:
+
+```bash
+git reflog
+git checkout -b <branch-name> <commit-id>
+```
+
+Fix detached HEAD:
+
+```bash
+git checkout main
+```
+
+---
+
+## 16. Clone Repository
+
+Clone via SSH:
+
+```bash
+git clone git@github.com:user/repo.git
+```
+
+Clone specific branch:
+
+```bash
+git clone -b <branch> <repo-url>
+```
+