git.md

git

Create a new repository

git init
Initialized empty Git repository in /Users/schneidersjosef/temp/.git/

This command creates a new hidden folder, .git. This folder is the repository, which means that all version control happens here. Note that no server is involved here. All happens on your local machine.

Commit a new file

Place a new file in your directory. Then type in git status.

On branch master

Initial commit

Untracked files:
  (use "git add <file>..." to include in what will be committed)

	hello.txt

nothing added to commit but untracked files present (use "git add" to track)

It says, there is a new file git doesn't know about. To 'introduce' the file to git, type this:

git add hello.txt

This adds hello.txt to the staging area. This means, when you do a commit, this file will be considered for the commit. Only files which are staged will be part of the new commit.

To do the commit, type in git commit. The default editor opens and you can type in your commit message. Your commit message should be ~ 50-70 chars long.

View the history

git stores the history of changes you did to all files. To view it, type in git log. Now you see all commits which have been made on the current branch.

To close this view, type in q.

Undo changes

Given the case you did changes to a file you want to undo. You can tell git to restore the last version of the file. At first, type in git status. Then you will see this:

On branch master
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

	modified:   hello.txt

no changes added to commit (use "git add" and/or "git commit -a")

git says, hello.txt changed. To see what has changed, type in git diff:

diff --git a/hello.txt b/hello.txt
index 1244ed0..5d799c6 100644
--- a/hello.txt
+++ b/hello.txt
@@ -1 +1 @@
-Alice wrote this line
+Alice changed this line

You see, one line changed. To undo this change, you check out this file. This means, git overwrites the current version whith its latest version. All changes will be lost.

git checkout hello.txt