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diff --git a/git.html.markdown b/git.html.markdown new file mode 100644 index 00000000..00f38d60 --- /dev/null +++ b/git.html.markdown @@ -0,0 +1,388 @@ +--- +category: tool +tool: git +contributors: + - ["Jake Prather", "http:#github.com/JakeHP"] +filename: LearnGit.txt + +--- + +Git is a distributed version control and source code management system. + +It does this through a series of snapshots of your project, and it works +with those snapshots to provide you with functionality to version and +manage your source code. + +## Versioning Concepts + +### What is version control? + +Version control is a system that records changes to a file, or set of files, over time. + +### Centralized Versioning VS Distributed Versioning + +* Centralized version control focuses on synchronizing, tracking, and backing up files. +* Distributed version control focuses on sharing changes. Every change has a unique id. +* Distributed systems have no defined structure. You could easily have a SVN style, centralized system, with git. + +[Additional Information](http://git-scm.com/book/en/Getting-Started-About-Version-Control) + +### Why Use Git? + +* Can work offline. +* Collaborating with others is easy! +* Branching is easy! +* Merging is easy! +* Git is fast. +* Git is flexible. + +## Git Architecture + + +### Repository + +A set of files, directories, historical records, commits, and heads. Imagine it as a source code datastructure, +with the attribute that each source code "element" gives you access to its revision history, among other things. + +A git repository is comprised of the .git directory & working tree. + +### .git Directory (component of repository) + +The .git directory contains all the configurations, logs, branches, HEAD, and more. +[Detailed List.](http://gitready.com/advanced/2009/03/23/whats-inside-your-git-directory.html) + +### Working Tree (component of repository) + +This is basically the directories and files in your repository. It is often referred to +as your working directory. + +### Index (component of .git dir) + +The Index is the staging area in git. It's basically a layer that separates your working tree +from the Git repository. This gives developers more power over what gets sent to the Git +repository. + +### Commit + +A git commit is a snapshot of a set of changes, or manipulations to your Working Tree. +For example, if you added 5 files, and removed 2 others, these changes will be contained +in a commit (or snapshot). This commit can then be pushed to other repositories, or not! + +### Branch + +A branch is essentially a pointer that points to the last commit you made. As you commit, +this pointer will automatically update and point to the latest commit. + +### HEAD and head (component of .git dir) + +HEAD is a pointer that points to the current branch. A repository only has 1 *active* HEAD. +head is a pointer that points to any commit. A repository can have any number of heads. + +### Conceptual Resources + +* [Git For Computer Scientists](http://eagain.net/articles/git-for-computer-scientists/) +* [Git For Designers](http://hoth.entp.com/output/git_for_designers.html) + + +## Commands + + +### init + +Create an empty Git repository. The Git repository's settings, stored information, +and more is stored in a directory (a folder) named ".git". + +```bash +$ git init +``` + +### config + +To configure settings. Whether it be for the repository, the system itself, or global +configurations. + + +```bash +# Print & Set Some Basic Config Variables (Global) +$ git config --global user.email +$ git config --global user.name + +$ git config --global user.email "MyEmail@Zoho.com" +$ git config --global user.name "My Name" +``` + +[Learn More About git config.](http://git-scm.com/docs/git-config) + +### help + +To give you quick access to an extremely detailed guide of each command. Or to +just give you a quick reminder of some semantics. + +```bash +# Quickly check available commands +$ git help + +# Check all available commands +$ git help -a + +# Command specific help - user manual +# git help <command_here> +$ git help add +$ git help commit +$ git help init +``` + +### status + +To show differences between the index file (basically your working copy/repo) and the current +HEAD commit. + + +```bash +# Will display the branch, untracked files, changes and other differences +$ git status + +# To learn other "tid bits" about git status +$ git help status +``` + +### add + +To add files to the current working tree/directory/repo. If you do not `git add` new files to the +working tree/directory, they will not be included in commits! + +```bash +# add a file in your current working directory +$ git add HelloWorld.java + +# add a file in a nested dir +$ git add /path/to/file/HelloWorld.c + +# Regular Expression support! +$ git add ./*.java +``` + +### branch + +Manage your branches. You can view, edit, create, delete branches using this command. + +```bash +# list existing branches & remotes +$ git branch -a + +# create a new branch +$ git branch myNewBranch + +# delete a branch +$ git branch -d myBranch + +# rename a branch +# git branch -m <oldname> <newname> +$ git branch -m myBranchName myNewBranchName + +# edit a branch's description +$ git branch myBranchName --edit-description +``` + +### checkout + +Updates all files in the working tree to match the version in the index, or specified tree. + +```bash +# Checkout a repo - defaults to master branch +$ git checkout +# Checkout a specified branch +$ git checkout branchName +# Create a new branch & switch to it, like: "git branch <name>; git checkout <name>" +$ git checkout -b newBranch +``` + +### clone + +Clones, or copies, an existing repository into a new directory. It also adds +remote-tracking branches for each branch in the cloned repo, which allows you to push +to a remote branch. + +```bash +# Clone learnxinyminutes-docs +$ git clone https://github.com/adambard/learnxinyminutes-docs.git +``` + +### commit + +Stores the current contents of the index in a new "commit." This commit contains +the changes made and a message created by the user. + +```bash +# commit with a message +$ git commit -m "Added multiplyNumbers() function to HelloWorld.c" +``` + +### diff + +Shows differences between a file in the working directory, index and commits. + +```bash +# Show difference between your working dir and the index +$ git diff + +# Show differences between the index and the most recent commit. +$ git diff --cached + +# Show differences between your working dir and the most recent commit +$ git diff HEAD +``` + +### grep + +Allows you to quickly search a repository. + +Optional Configurations: + +```bash +# Thanks to Travis Jeffery for these +# Set line numbers to be shown in grep search results +$ git config --global grep.lineNumber true + +# Make search results more readable, including grouping +$ git config --global alias.g "grep --break --heading --line-number" +``` + +```bash +# Search for "variableName" in all java files +$ git grep 'variableName' -- '*.java' + +# Search for a line that contains "arrayListName" and, "add" or "remove" +$ git grep -e 'arrayListName' --and \( -e add -e remove \) +``` + +Google is your friend; for more examples +[Git Grep Ninja](http://travisjeffery.com/b/2012/02/search-a-git-repo-like-a-ninja) + +### log + +Display commits to the repository. + +```bash +# Show all commits +$ git log + +# Show X number of commits +$ git log -n 10 + +# Show merge commits only +$ git log --merges +``` + +### merge + +"Merge" in changes from external commits into the current branch. + +```bash +# Merge the specified branch into the current. +$ git merge branchName + +# Always generate a merge commit when merging +$ git merge --no-ff branchName +``` + +### mv + +Rename or move a file + +```bash +# Renaming a file +$ git mv HelloWorld.c HelloNewWorld.c + +# Moving a file +$ git mv HelloWorld.c ./new/path/HelloWorld.c + +# Force rename or move +# "existingFile" already exists in the directory, will be overwritten +$ git mv -f myFile existingFile +``` + +### pull + +Pulls from a repository and merges it with another branch. + +```bash +# Update your local repo, by merging in new changes +# from the remote "origin" and "master" branch. +# git pull <remote> <branch> +$ git pull origin master +``` + +### push + +Push and merge changes from a branch to a remote & branch. + +```bash +# Push and merge changes from a local repo to a +# remote named "origin" and "master" branch. +# git push <remote> <branch> +# git push => implicitly defaults to => git push origin master +$ git push origin master +``` + +### rebase (caution) + +Take all changes that were committed on one branch, and replay them onto another branch. +*Do not rebase commits that you have pushed to a public repo*. + +```bash +# Rebase experimentBranch onto master +# git rebase <basebranch> <topicbranch> +$ git rebase master experimentBranch +``` + +[Additional Reading.](http://git-scm.com/book/en/Git-Branching-Rebasing) + +### reset (caution) + +Reset the current HEAD to the specified state. This allows you to undo merges, +pulls, commits, adds, and more. It's a great command but also dangerous if you don't +know what you are doing. + +```bash +# Reset the staging area, to match the latest commit (leaves dir unchanged) +$ git reset + +# Reset the staging area, to match the latest commit, and overwrite working dir +$ git reset --hard + +# Moves the current branch tip to the specified commit (leaves dir unchanged) +# all changes still exist in the directory. +$ git reset 31f2bb1 + +# Moves the current branch tip backward to the specified commit +# and makes the working dir match (deletes uncommited changes and all commits +# after the specified commit). +$ git reset --hard 31f2bb1 +``` + +### rm + +The opposite of git add, git rm removes files from the current working tree. + +```bash +# remove HelloWorld.c +$ git rm HelloWorld.c + +# Remove a file from a nested dir +$ git rm /pather/to/the/file/HelloWorld.c +``` + +## Further Information + +* [tryGit - A fun interactive way to learn Git.](http://try.github.io/levels/1/challenges/1) + +* [git-scm - Video Tutorials](http://git-scm.com/videos) + +* [git-scm - Documentation](http://git-scm.com/docs) + +* [Atlassian Git - Tutorials & Workflows](https://www.atlassian.com/git/) + +* [SalesForce Cheat Sheet](https://na1.salesforce.com/help/doc/en/salesforce_git_developer_cheatsheet.pdf) + +* [GitGuys](http://www.gitguys.com/) |