Howto: What is Git and Github? How do I use it and why should I care?

Makes a copy of a git repository.

For example, whenever you download things from a github/git site (repository), you’ll be using clone.
eg: git clone https://github.com/YOUR-USERNAME/YOUR-REPOSITORY.git

Shows the status of the repository.

You’ll do this often, so you can track any changes to the repository.
eg: git status

Adds file(s) to a staging area, so that changes can be tracked locally.

Tells git to start tracking changes for the file you specify. Note that this doesn’t commit them to the branch, it’s in a local staging area, e.g:

git add <filename>

To add multiple files/directories, you need parentheses around wildcards so that git gets the list of files before the shell operates on the wildcard. This example adds every .jpg file in all the directories below the current directory (including the current directory):

git add '*.jpg'

Commit a staged (added) change.

To commit a change means “all of these add’s I’ve done, take them out of the staging area and commit them to my repository”. It’s mandatory to commit with a message. The message should describe what the commit is for, eg, you could say that you’ve added a few jpegs of cats.
git commit -m "info about this commit".

Configure a remote repository to push commits to.

Any changes you have committed locally can be uploaded to a remote repository. Github is a remote repository for example. To initialise your remote git server connection, you use git remote.

Eg: git remote add origin https://github.com/YOUR-USERNAME/your-repository.git

• The name (or handle) ‘origin’ is used as a reference for the remote project repository. You can name it anything you like, however it is typical to name your main one ‘origin’ though.
• The your-repository.git file is created when you do a git init.

Push committed changes to a remote repository.

Once you have initialised your remote repository, you can push the committed changes to it with push:
git push -u origin master

• ‘origin’ is the name you specified for the remote connection.
• ‘master’ is the branch called master (the primary branch. More on this in a minute).
• the -u option tells git to remember the paramaters you specified, so you only need to type ‘git push’ the next time.

Merges changes from the remote repository with your local copy.

Once people (or you) have committed more changes to the repository, you want to issue a pull request to merge the changes you have locally with the upstream (remote) repository.

git pull origin master

Shows what differences there have been to the repository since the last commit.

When changes are committed to the remote repository by more than one person, there will be differences between what you have stored locally and that which is on the remote server. Differences are called diffs. When you do a pull, this will let your local

To view the differences between your most recent commit and that of what exists in the remote repository, you can use the HEAD pointer. HEAD is simply a position indicator, by default it points to your most recent commits.

git diff HEAD

The output will show the differences between your copy of any changed files, vs the remote copy (adds and subtractions).

To see differences between the files in your staging (added) area and the local files on your PC, use diff --staged

Revert to a previous commit, or switch branches.

Let’s just say that you made a commit of file.txt that you decided was no good, and you wanted to go back to a previous committed version, you’d revert it as so:

git checkout -- file.txt

• The — simply says that there are no more options to the checkout operation.

To change a branch, specify the branch name (rather than using the — or supplying a filename to revert):

git checkout <branchname>

Creates a new copy (branch). The command also deletes or lists present branches.

For more information on what a ‘branch’ is, see the terminology below. The below example creates a new branch called ‘newbranch’:

git branch newbranch

The below example deletes ‘newbranch‘:

git branch -d newbranch

Removes files from the current branch, as well as the local disk.

To remove all of the files, use rm just like you would an add:

git rm '*.txt'

• Don’t forget to commit that change after you issue the rm!

Merges one branch into another.

As a practical example, continuing on from the rm command example above, lets assume that you performed an rm *.txt from the branch newbranch. If you wanted to merge that change into the master branch, firstly you would switch back to the master branch by issuing git checkout master, then using the merge command to merge the differences from newbranch back to the current branch (master). Most teams of developers will work on their code in separate branches before merging them into the master branch at the end of the day.

git merge newbranch

Reverts (removes) any staged changes.

For example, if you have done a git add file.txt, but then before you commit, you decide that file.txt should not be committed, issue the reset command, e.g.:git reset file.txt

Show a journal of all of the committed changes.

Eg: git log