Configuration

git config --global core.editor "vim"

Discarding Modifications

// Unstage files from the index
# Step 1: Move changes from index to working directory
git reset HEAD path/to/file
# Step 2: Discard changes in the working directory
git checkout -- path/to/file

// Restore a specific file to a previous revision
git checkout <commitHash> -- <filename>

Consolidating Commits

git rebase -i HEAD~3   // Or specify a starting commit_id

# Commands available during rebase:
# pick: Use the commit as is (default)
# squash: Combine this commit with the previous one
# fixup: Combine with the previous commit, discarding this log message
# drop: Remove the commit entirely

// Modifying the most recent commit:
git commit --amend

Force Local Overwrite

git fetch --all
git reset --hard origin/main

Inspecting History

// Show changes introduced by a specific commit
git show <commit-hash> [<filename>]

// Show file statistics for a specific commit
git show <commit-hash> --stat

// Show recent commit history with stats
git log -2 --stat

// Compact log view
git log --pretty=oneline

// Reference log: tracks all operations including deleted commits
git reflog

Initializing Remote Repository

git init
git remote add origin https://github.com/username/repository.git
git pull --rebase origin main  // Use 'git pull origin main' if rebase is not desired

// Set upstream to avoid specifying remote branch later
git branch --set-upstream-to=origin/main main

git add .
git commit -m "Initial commit"
git push -u origin main

Reverting History

// History: v1 --> v2 --> v3

// reset: Move HEAD pointer back (destructive)
git reset --hard HEAD~1  // Move back 1 commit (HEAD^, HEAD~1, HEAD~10 etc.)
git reset --hard <commit_id> // Jump to specific hash (first 6-7 chars suffice)
git push -f // Force push required after reset

// revert: Create a new commit that undoes changes (non-destructive)
// Example: Removing changes from v2 creates v4
git revert -n <commit_id>

Comparing Versions

// Compare working directory with index (HEAD)
git diff HEAD -- src/login.py

// Compare two different commits
git diff HEAD HEAD^ -- src/login.py

// List only filenames changed between two commits
git diff 2da595c daea1d6 --name-only

Fetching and Merging

// git pull is equivalent to fetch followed by merge
git fetch origin main    // Download remote data to local references
// Optional: git log -p main..origin/main // Inspect differences before merging
git merge origin/main     // Integrate remote changes

Branch Integration Strategies

// Merge Strategy:
git checkout feature
git merge main
// Or single line:
git merge main feature

// Creates a merge commit preserving history from both branches.
// Safer operation as it does not alter existing branch history.

// Rebase Strategy:
git checkout feature
git rebase main    // Use -i for interactive mode

// Moves the feature branch to the tip of main, replaying feature commits on top.
// Warning: Rewrites history. Use with caution if feature branch is shared.