#90DaysOfDevOps - Gitting to know Git - Day 37

Gitting to know Git

Apologies for the terrible puns in the title and throughout. I am surely not the first person to turn Git into a dad joke!

In the last two posts we learnt about version control systems, and some of the fundamental workflows of git as a version control system Day 35 Then we got git installed on our system, updated and configured. We also went a little deeper into the theory between the Client-Server version control system and Git which is a distributed version control system Day 36.

Now we are going to run through some of the commands and use cases that we will all commonly see with git.

Where to git help with git?

There are going to be times when you just cannot remember or just don't know the command you need to get things done with git. You are going to need help.

Google or any search engine is likely to be your first port of call when searching for help.

Secondly, the next place is going to be the official git site and the documentation. git-scm.com/docs Here you will find not only a solid reference to all the commands available but also lots of different resources.

We can also access this same documentation which is super useful if you are without connectivity from the terminal. If we chose the git add command for example we can run git add --help and we see below the manual.

We can also in the shell use git add -h which is going to give us a summary of the options we have available.

Myths surrounding Git

"Git has no access control" - You can empower a leader to maintain source code.

"Git is too heavy" - Git can provide shallow repositories which means a reduced amount of history if you have large projects.

Real shortcomings

Not ideal for Binary files. Great for source code but not great for executable files or videos for example.

Git is not user-friendly, the fact that we have to spend time talking about commands and functions of the tool is probably a key sign of that.

Overall though, git is hard to learn but easy to use.

The git ecosystem

I want to briefly cover the ecosystem around git but not deep dive into some of these areas but I think it's important to note these here at a high level.

Almost all modern development tools support Git.

Developer tools - We have already mentioned visual studio code but you will find git plugins and integrations into sublime text and other text editors and IDEs.
Team tools - Also mentioned around tools like Jenkins from a CI/CD point of view, Slack from a messaging framework and Jira for project management and issue tracking.
Cloud Providers - All the large cloud providers support git, Microsoft Azure, Amazon AWS, and Google Cloud Platform.
Git-Based services - Then we have GitHub, GitLab and BitBucket which we will cover in more detail later on. I have heard of these services as the social network for code!

The Git Cheatsheet

We have not covered most of these commands but having looked at some cheat sheets available online I wanted to document some of the git commands and what their purpose is. We don't need to remember these all, and with more hands-on practice and use you will pick at least the git basics.

I have taken these from atlassian but writing them down and reading the description is a good way to get to know what the commands are as well as getting hands-on in everyday tasks.

Git Basics

Command	Example	Description
git init	`git init <directory>`	Create an empty git repository in the specified directory.
git clone	`git clone <repo>`	Clone repository located at onto local machine.
git config	`git config user.name`	Define author name to be used for all commits in current repository `system`, `global`, `local` flag to set config options.
git add	`git add <directory>`	Stage all changes in for the next commit. We can also add and <.> for everything.
git commit -m	`git commit -m "<message>"`	Commit the staged snapshot, use to detail what is being committed.
git status	`git status`	List files that are staged, unstaged and untracked.
git log	`git log`	Display all commit history using the default format. There are additional options with this command.
git diff	`git diff`	Show unstaged changes between your index and working directory.

Git Undoing Changes

Command	Example	Description
git revert	`git revert <commit>`	Create a new commit that undoes all of the changes made in then apply it to the current branch.
git reset	`git reset <file>`	Remove from the staging area, but leave the working directory unchanged. This unstaged a file without overwriting any changes.
git clean	`git clean -n`	Shows which files would be removed from the working directory. Use `-f` in place of `-n` to execute the clean.

Git Rewriting History

Command	Example	Description
git commit	`git commit --amend`	Replace the last commit with the staged changes and the last commit combined. Use with nothing staged to edit the last commit’s message.
git rebase	`git rebase <base>`	Rebase the current branch onto . can be a commit ID, branch name, a tag, or a relative reference to HEAD.
git reflog	`git reflog`	Show a log of changes to the local repository’s HEAD. Add --relative-date flag to show date info or --all to show all refs.

Git Branches

Command	Example	Description
git branch	`git branch`	List all of the branches in your repo. Add a argument to create a new branch with the name .
git checkout	`git checkout -b <branch>`	Create and check out a new branch named . Drop the -b flag to checkout an existing branch.
git merge	`git merge <branch>`	Merge into the current branch.

Git Remote Repositories

Command	Example	Description
git remote add	`git remote add <name> <url>`	Create a new connection to a remote repo. After adding a remote, you can use as a shortcut for in other commands.
git fetch	`git fetch <remote> <branch>`	Fetches a specific , from the repo. Leave off to fetch all remote refs.
git pull	`git pull <remote>`	Fetch the specified remote’s copy of current branch and immediately merge it into the local copy.
git push	`git push <remote> <branch>`	Push the branch to , along with necessary commits and objects. Creates named branch in the remote repo if it doesn’t exist.

Git Diff

Command	Example	Description
git diff HEAD	`git diff HEAD`	Show the difference between the working directory and the last commit.
git diff --cached	`git diff --cached`	Show difference between staged changes and last commit

Git Config

Command	Example	Description
git config --global user.name	`git config --global user.name <name>`	Define the author name to be used for all commits by the current user.
git config --global user.email	`git config --global user.email <email>`	Define author email to be used for all commits by the current user.
git config --global alias	`git config --global alias <alias-name> <git-command>`	Create shortcut for a git command .
git config --system core.editor	`git config --system core.editor <editor>`	Set the text editor to be used by commands for all users on the machine. arg should be the comamnd that launches the desired editor.
git config --global --edit	`git config --global --edit`	Open the global configuration file in a text editor for manual editing.

Git Rebase

Command	Example	Description
git rebase -i	`git rebase -i <base>`	Interactively rebase current branch onto . Launches editor to enter commands for how each commit will be transferred to the new base.

Git Pull

Command	Example	Description
git pull --rebase	`git pull --rebase <remote>`	Fetch the remote’s copy of current branch and rebases it into the local copy. Uses git rebase instead of the merge to integrate the branches.

Git Reset

Command	Example	Description
git reset	`git reset`	Reset the staging area to match the most recent commit but leave the working directory unchanged.
git reset --hard	`git reset --hard`	Reset staging area and working directory to match most recent commit and overwrites all changes in the working directory
git reset	`git reset <commit>`	Move the current branch tip backwards to , reset the staging area to match, but leave the working directory alone
git reset --hard	`git reset --hard <commit>`	Same as previous, but resets both the staging area & working directory to match. Deletes uncommitted changes, and all commits after .

Git Push

Command	Example	Description
git push --force	`git push <remote> --force`	Forces the git push even if it results in a non-fast-forward merge. Do not use the --force flag unless you’re sure you know what you’re doing.
git push --all	`git push <remote> --all`	Push all of your local branches to the specified remote.
git push --tags	`git push <remote> --tags`	Tags aren’t automatically pushed when you push a branch or use the --all flag. The --tags flag sends all of your local tags to the remote repo.

Resources

See you on Day 38