add a cheatsheet for git commands

cheatsheet.md

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+# Git cheatsheet
+
+## Creating a repository
+```bash
+git init
+```
+Creates new git repository in current directory.
+
+```bash
+git clone <url> (<path>)
+```
+Clones the repository at the specified url. If no path is specified, the repository will
+be cloned into a directory with the same name as the remote repository.
+
+
+## Branches
+```bash
+git branch
+```
+Lists all branches in the repository.
+
+```bash
+git branch <branch-name>
+```
+Creates a new branch with the given name.
+
+```bash
+git switch <branch-name>
+```
+Switches to the specified branch.
+
+```bash
+git merge <branch-name>
+```
+Merges the specified branch into the current branch.
+
+
+## Making changes
+```bash
+git status
+```
+Shows the status of the repository. This includes the current branch and files that have been modified.
+
+```bash
+git diff (--staged)
+```
+Shows the changes that have been made to the files in the repository. Use `--staged` to see changes that have been added to the staging area.
+
+```bash
+git add <file>
+```
+Adds the specified file to the staging area.
+
+```bash
+git add .
+```
+Adds all files in the current directory to the staging area.
+
+```bash
+git reset (<file>)
+```
+Removes the specified file from the staging area. If no file is specified, all files are removed.
+
+```bash
+git commit (-m "<message>")
+```
+Commits all changes in the staging area to the current branch. If the `-m` flag is omitted, a text editor will open to write a commit message.
+
+```bash
+git commit --amend
+```
+Adds the staged changes to the last commit. This can be used for fixing typos in the commit message.
+
+
+## Undoing changes
+```bash
+git restore <file>
+```
+Restores the specified file to the state of the last commit. This undoes uncommitted changes.
+
+```bash
+git revert <commit>
+```
+Creates a new commit that undoes the changes of the specified commit. Use `git log` to find the hash of the commit.
+
+```bash
+git reset --hard <commit>
+```
+Resets the current branch to the specified commit. DANGER: This will remove all changes after the specified commit. Prefer `git revert`.
+
+
+## Looking at the history
+```bash
+git log (--oneline)
+```
+Shows all past commits on the current branch. Use `--oneline` to show a more compact view.
+
+```bash
+git show <commit>
+```
+Shows the changes of the specified commit. Use `git log` to find the has of the commit.
+
+
+## Remote repositories
+```bash
+git remote add <remote> <url>
+```
+Adds a new remote repository with the specified name (e.g. `origin` or `upstream`) and url. Origin is automatically created when cloning a repository.
+
+```bash
+git push <remote> <branch>
+```
+Pushes the specified branch to the remote repository.
+
+```bash
+git fetch <remote>
+```
+Fetches changes from the remote repository.
+
+```bash
+git pull <remote> <branch>
+```
+Fetches changes from the remote repository and merges them into the current branch.
+
+
+## Typical workflow
+```bash
+# 1. Fork the repository on GitHub / git.aspp.school
+
+# 2. Clone the repository
+git clone <fork-url>
+git remote add upstream <upstream-url>
+
+# 3. Create a new branch
+git branch <topic-branch>
+git switch <topic-branch>
+
+# 4. Make changes to the code
+
+# 5. Add and commit changes
+git add .
+git commit -m "<message>"
+
+# 6. Push changes to your fork
+git push origin <topic-branch>
+
+# 7. Create a pull request on GitHub / git.aspp.school
+
+# 8. Wait for the pull request to be reviewed and merged
+
+# 9. Pull changes from the remote repository
+git switch main
+git pull upstream main
+
+# 10. Delete the topic branch
+git branch -d <topic-branch>
+```
+
+Whenever the remote repository is updated (i.e. when a pull request is merged), you need to pull the changes into your local repository.
+```bash
+git switch main
+git pull upstream main
+
+# If you have an active topic branch, you need to rebase it on top of the updated main branch
+git switch <topic-branch>
+git rebase main
+```
+
+
+## Getting help
+```bash
+git help <command>
+```
+Shows the manual page for the specified command (`add`, `commit`, `push`, etc.).
+
+Official Git documentation: https://git-scm.com/docs