1. habeeb rahman | hrahman@apigee.com | pk.habi@gmail.com
Get on with Git

2. topics
git way
basic commands

3. git way
direct acyclic graph
sha-1 hash
git objects: blob tree commit tag

4. sha-1 & blob
(master) $ echo -e 'blob 140Hello, World!' | shasum
8ab686eafeb1f44702738c8b0f24f2567c36da6d
(master) $ echo 'Hello, World!' | git hash-object -w --stdin
8ab686eafeb1f44702738c8b0f24f2567c36da6d
(master) $ ls .git/objects/8a
b686eafeb1f44702738c8b0f24f2567c36da6d
(master) $ git show 8ab686eafeb1f44702738c8b0f24f2567c36da6d
Hello, World!

5. sha-1 & blob
(master)$ git cat-file -p 8ab686eafeb1f44702738c8b0f24f2567c36da6d
Hello, World!
(master)$ git cat-file -t 8ab686eafeb1f44702738c8b0f24f2567c36da6d
blob

6. sha-1 and tree
git cat-file -p master^{tree}

7. sha-1 and commit
(master)$ git show
commit 0184521b4bc88bbb67891ed740140147c9ce61cd
Author: Habeeb Rahman <hrahman@apigee.com>
Date:......
(master)$ git cat-file -t 0184521b4bc88bbb67891ed740140147c9ce61cd
commit

8. behind the scene
working directory
working
directory git add
committed
snapshotgit commit
index
(stage)

9. Basic commands

10. first things first
let git know your name and email:
git config --global user.name "Your Name"
git config --global user.email "your_email@whatever.com"

11. git init
Create an empty git repository or reinitialize an existing one
$ mkdir getonwithgit
$ cd getonwithgit/
$ git init
Initialized empty Git repository in /Users/hrahman/test/getonwithgit/.git/

12. git add
(master)$ echo "Hello World" > hello.txt
(master)$ 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)
(master)$ git add hello.txt
(master)$ git status
# On branch master
# Initial commit
# Changes to be committed:
# (use "git rm --cached <file>..." to unstage)
# new file: hello.txt

13. git commit
(master)$ git commit -m "first commit"
[master (root-commit) 05e96c3] first commit
1 files changed, 1 insertions(+), 0 deletions(-)
create mode 100644 hello.txt
(master)$ git show
commit 05e96c39452126e9310e84203af72f141c37a493
Author: Habeeb Rahman <hrahman@apigee.com>
Date: Tue Jun 18 13:46:35 2013 +0530
first commit
diff --git a/hello.txt b/hello.txt
new file mode 100644
index 0000000..557db03
--- /dev/null
+++ b/hello.txt
@@ -0,0 +1 @@
+Hello World

14. git diff
git diff: Show differences between your working directory and the
index.
git diff –cached: Show differences between the index and the
most recent commit.
git diff HEAD: Show the differences between your working
directory and the most recent commit.

15. git commit --amend
you commit and then realize you forgot to stage the changes in a file
you wanted to add to this commit:
$ git commit -m 'initial commit'
$ git add forgotten_file
$ git commit --amend

16. branch
create a new branch:
(master)$ git checkout -b dev_feature
Switched to a new branch 'dev_feature'
switch to an existing branch:
(dev_feature)$ git checkout master
Switched to branch 'master'
(dev_feature)$ echo "new feature" > feature.txt
(dev_feature)$ git add feature.txt
(dev_feature)$ git commit -m "feature"

17. branch
delete a branch
$git branch -d dev_new_branch
show all local branches:
$git branch
show all local and remote branches:
$git branch -a

18. branch & merge

19. merge
merge 'dev_feature' branch into 'master':
(dev_feature)$ git checkout master
Switched to branch 'master'
find out what's going to be merged:
(master)$ git diff master...dev_feature
diff --git a/feature.txt b/feature.txt
new file mode 100644
index 0000000..2c61ec4
--- /dev/null
+++ b/feature.txt
@@ -0,0 +1 @@
+new feature added
(master)$ git merge dev_feature
Updating 05e96c3..70c1e30
Fast-forward
feature.txt | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
create mode 100644 feature.txt

20. git blame
(master)$ git blame feature.txt
70c1e306 (Habeeb Rahman 2013-06-18 15:50:47 +0530 1) new
feature added

21. git log
(master)$ git log
commit 70c1e3069a68877fca9680b045185288c5201a46
Author: Habeeb Rahman <hrahman@apigee.com>
Date: Tue Jun 18 15:50:47 2013 +0530
feature
commit 05e96c39452126e9310e84203af72f141c37a493
Author: Habeeb Rahman <hrahman@apigee.com>
Date: Tue Jun 18 13:46:35 2013 +0530
first commit
(master)$ git log --oneline
70c1e30 feature
05e96c3 first commit

22. git grep
(master)$ git grep hello
hello.txt:hello world
new.txt:hello everyone

23. git clone
Local:
git clone /path/to/repository
Remote:
git clone git://github.com/sample/test.git

24. git help
display help information about git
$ git help help
$ git help grep
$ git help reset

25. further reading
http://git-scm.com/book
http://think-like-a-git.net/
http://ftp.newartisans.com/pub/git.from.bottom.up.pdf