Version Control with Git for Beginners

1. Version Control
with Git

2. Installation
Windows: http://msysgit.github.io/
Mac: http://code.google.com/p/git-osx-installer
Linux (Debian/Ubuntu):
apt-get install git-core gitk
Linux (Fedora):
yum install git gitk

3. Verify installation
Windows: Open "Git Bash"
Mac/Linux: Open your terminal
To verify, run:
$ git --version

4. Yes, we are going to use
the command line today
Feel free to use graphical interfaces after you learn the basics.

5. Initial Setup
$ git config --global user.name "Your Name"
$ git config --global user.email "your_email@whatever.com"
Windows:
$ git config --global core.autocrlf true
$ git config --global core.safecrlf true
Linux/Mac:
$ git config --global core.autocrlf input
$ git config --global core.safecrlf true

6. Version Control

7. Version Control
aka Revision Control

8. Version Control
aka Revision Control
aka How we do things in the Real World

9. Sharing Code

10. Working as a Team

12. Version Control

13. Why Version Control?

14. Reason #1:
"Versioning"

17. Wait a minute...

19. Finer-grained Control

21. Enough talk. Let's begin...

22. Create your first repository
$ mkdir devcon-git101
$ cd devcon-git101
$ git init

23. Create your first repository
$ mkdir devcon-git101
$ cd devcon-git101
$ git init

24. Create your first repository
$ mkdir devcon-git101
$ cd devcon-git101
$ git init
Here we create a project folder

25. Create your first repository
$ mkdir devcon-git101
$ cd devcon-git101
… Then we initialize it as a git repository.
$ git init

26. Create your first repository
$ mkdir devcon-git101
$ cd devcon-git101
… Then we initialize it as a git repository.
$ git init
Git can now track the changes inside our
project folder.

27. Create your first commit
First create a file "hello.txt" containing:
Hello
Then run the following commands:
$ git add hello.txt
$ git commit -m "Initial Commit"

28. View the repository history
$ git log
(press q to exit)

29. View the pretty repo history
$ git log --graph --pretty=oneline
(press q to exit)

30. Ah, what the hell...
Windows/Linux:
$ gitk
Mac:
$ gitx

31. Create your second commit
Modify "hello.txt" to add "world":
Hello World!
Then run the following commands:
$ git add hello.txt
$ git commit -m "Make hello.txt more exciting"

32. View the updated history
Windows/Linux:
$ gitk
Mac:
$ gitx

33. What just happened?

34. http://git-scm.com/book/en/Getting-Started-Git-Basics

35. git add
git commit
http://git-scm.com/book/en/Getting-Started-Git-Basics

36. 6fba518
Initial Commit

37. 6fba518
Initial Commit
object name
●
●
aka object id, commit hash
SHA-1 hash / checksum for verifying the integrity of the contents of the commit
Calculated based on file contents and metadata like last updated date i.e. yours
will be different

38. e642771
Make hello.txt more exciting
6fba518
Initial Commit

39. e642771
No, this is not a mistake;
commits refer to their
parent(s), not the other
way around.
Make hello.txt more exciting
6fba518
Initial Commit

40. Commit multiple files
Create a file "names.txt" containing:
Alice
Bob
Cindy

41. Commit multiple files
Create a file "numbers.txt" containing:
3
9
16
12
8.2
4

42. Commit multiple files
Run the following commands:
$ git add names.txt numbers.txt
$ git commit -m "Create 2 files in a single commit"

43. e642771
Make hello.txt more exciting
6fba518
Initial Commit

44. Each commit deals with a set of files
7c57165
Create 2 files in a single commit
2 files created
e642771
Make hello.txt more exciting
1 file modified
6fba518
Initial Commit
1 file created

45. We've covered "Save", but
before we move on to
"Load"...

46. http://git-scm.com/book/en/Git-Basics-Recording-Changes-to-the-Repository

47. File Status
(all unmodified)
$ git status
# On branch master
nothing to commit, working directory clean

48. File Status
(untracked)
Create a file "animals.txt" containing:
Dogs
Cats
Mice

49. File Status
(untracked)
$ git status
# On branch master
# Untracked files:
#
(use "git add <file>..." to include in
what will be committed)
#
#
animals.txt
nothing added to commit but untracked files
present (use "git add" to track)

50. File Status
(untracked and modified)
Modify "names.txt" to add "Janet":
Alice
Bob
Janet
Cindy

51. File Status
(untracked and modified)
$ git status
# 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:
names.txt
#
# Untracked files:
#
(use "git add <file>..." to include in what will be committed)
#
#
animals.txt
no changes added to commit (use "git add" and/or "git commit -a")

52. File Status
(untracked and staged)
$ git add names.txt
$ git status
# On branch master
# Changes to be committed:
#
(use "git reset HEAD <file>..." to unstage)
#
#
modified:
names.txt
#
# Untracked files:
#
(use "git add <file>..." to include in what will be
committed)
#
#
animals.txt

53. File Status
(commit staged)
$ git commit -m "Add Janet"
[master 5e545ed] Add Janet
1 file changed, 1 insertion(+)
$ git status
# On branch master
# Untracked files:
#
(use "git add <file>..." to include in what will be
committed)
#
#
animals.txt

54. Shortcuts

55. Stage a folder
Modify "names.txt" to add "Ramon":
Alice
Ramon
Bob
Janet
Cindy

56. Stage a folder
$
$
#
#
#
#
#
#
#
git add .
git status
On branch master
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
new file:
modified:
animals.txt
names.txt

57. Unstage a file
$ git reset HEAD names.txt
Unstaged changes after reset:
M
names.txt
$ git status
# On branch master
# Changes to be committed:
#
(use "git reset HEAD <file>..." to unstage)
#
#
new file:
animals.txt
#
# 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:
names.txt
#

58. Unmodify a file
$ git checkout -- names.txt
$ git status
# On branch master
# Changes to be committed:
#
(use "git reset HEAD <file>..." to unstage)
#
#
new file:
animals.txt
#

59. do it again...
Modify "names.txt" to add "Ramon":
Alice
Ramon
Bob
Janet
Cindy

60. Stage and commit
EVERYTHING
(except untracked files)
$ git commit -a -m "Commit unrelated changes.. DON'T DO THIS"
[master 61f1cd8] Commit unrelated changes.. DON'T DO THIS
2 files changed, 4 insertions(+)
create mode 100644 animals.txt
$ git status
# On branch master
nothing to commit, working directory clean
Note: using "-a" will also stage moved and renamed files.

61. Amend last commit
$ git commit -m "Commit unrelated changes... DON'T DO THIS" --amend
[master 3a0eac3] Commit unrelated changes... DON'T DO THIS
2 files changed, 4 insertions(+)
create mode 100644 animals.txt

62. On to "Load"...

63. 3a0eac3
Commit unrelated changes... DON'T DO THIS
5e545ed
Add Janet
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting
6fba518
Initial Commit

64. HEAD
3a0eac3
Commit unrelated changes... DON'T DO THIS
5e545ed
Add Janet
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting
6fba518
Initial Commit

65. Create a reverting commit
$ git revert HEAD --no-edit
[master 2a1b52e] Revert "Commit unrelated changes... DON'T DO THIS"
2 files changed, 4 deletions(-)
delete mode 100644 animals.txt

66. HEAD
3a0eac3
Commit unrelated changes... DON'T DO THIS
5e545ed
Add Janet
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting

67. HEAD
2a1b52e
Revert "Commit unrelated changes... DON'T
DO THIS"
3a0eac3
Commit unrelated changes... DON'T DO THIS
5e545ed
Add Janet
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting

68. Move HEAD to a commit
discarding changes
$ git reset --hard 7c57165
HEAD is now at 7c57165 Create 2 files in a single commit
(You can use the first few characters of the object ID instead of the 40 characters)

69. HEAD
2a1b52e
Revert "Commit unrelated changes... DON'T
DO THIS"
3a0eac3
Commit unrelated changes... DON'T DO THIS
5e545ed
Add Janet
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting

70. 2a1b52e
Revert "Commit unrelated changes... DON'T
DO THIS"
3a0eac3
Commit unrelated changes... DON'T DO THIS
5e545ed
Add Janet
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting
HEAD

71. View history
$
*
*
*
git log
7c57165
e642771
6fba518
--graph --pretty=format:'%h %s%d' --all
Create 2 files in a single commit (HEAD, master)
Make hello.txt more exciting
Initial Commit
or
$ gitk --all

72. HEAD
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting

73. Move HEAD to a commit
$ git reset --hard 2a1b52e
HEAD is now at 2a1b52e Revert "Commit unrelated changes... DON'T DO
THIS"

74. HEAD
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting

75. 2a1b52e
Revert "Commit unrelated changes... DON'T
DO THIS"
3a0eac3
Commit unrelated changes... DON'T DO THIS
5e545ed
Add Janet
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting
HEAD

76. HEAD
2a1b52e
Revert "Commit unrelated changes... DON'T
DO THIS"
3a0eac3
Commit unrelated changes... DON'T DO THIS
5e545ed
Add Janet
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting

77. Unreferenced commits will
not show up in the history.
Coincidentally, we can use
Tags to refer to a commit.

78. Tagging
$ git tag tagging-demo

79. HEAD
2a1b52e
Revert "Commit unrelated changes... DON'T
DO THIS"
3a0eac3
Commit unrelated changes... DON'T DO THIS
5e545ed
Add Janet
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting

80. tagging-demo
HEAD
2a1b52e
Revert "Commit unrelated changes... DON'T
DO THIS"
3a0eac3
Commit unrelated changes... DON'T DO THIS
5e545ed
Add Janet
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting

81. Going back...
$ git reset --hard 7c57165
HEAD is now at 7c57165 Create 2 files in a single commit

82. tagging-demo
2a1b52e
Revert "Commit unrelated changes... DON'T
DO THIS"
3a0eac3
Commit unrelated changes... DON'T DO THIS
5e545ed
Add Janet
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting
HEAD

83. View history
$
*
*
*
*
*
*
git log
2a1b52e
3a0eac3
5e545ed
7c57165
e642771
6fba518
--graph --pretty=format:'%h %s%d' --all
Revert "Commit unrelated changes... DON'T DO THIS" (tagging-demo)
Commit unrelated changes... DON'T DO THIS
Add Janet
Create 2 files in a single commit (HEAD, master)
Make hello.txt more exciting
Initial Commit
or
$ gitk --all

84. Wrapping up, tag current...
$ git tag end-part1

85. ...and unreference PDAF
$ git tag -d tagging-demo
Deleted tag 'tagging-demo' (was 2a1b52e)

86. end-part1
HEAD
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting
6fba518
Initial Commit

87. Best Practices

88. Write good commit
messages
You should be able to get an idea what changed
and why just by looking at the commit messages

89. Commit related changes
This would make it easier to roll back changes

90. Commit often

91. Do not commit generated files
E.g. compiled bytecode or executables, log files,
temporary files, etc.

92. Do not commit sensitive
information
E.g. passwords, settings.
You can, however, commit templates.

93. Helpful Stuff
that we will not explain in detail...

94. .gitignore
https://github.com/github/gitignore

95. git stash

96. git blame

97. Summary of Commands
git init - initialize repository
git add - add files/folders to staging
git commit - commit files in staging
git status - view status of repository
git log / gitk - view history of repository
git revert - unstage files
git reset - move HEAD to another commit
git tag - tag a commit

98. Summary of Command
Variations
git commit -a
- auto-stage all deleted, moved, modified
gitk --all / git log --all
- include all branches, tags
git tag -d
- delete tag

99. Why Version Control?

100. Reason #2:
Backup

101. Reason #2:
Backup

102. Reason #2:
Collaboration

103. If we were pressed for time...
Register at GitHub
● Learn git clone
● Learn git push / git pull
●
Learn how to fix merge conflicts
●

104. ...but we're not, so let's first
discuss something that will
help us later on.

105. Branching

106. File Status
(all unmodified)
$ git status
# On branch master
nothing to commit, working directory clean

107. File Status
(all unmodified)
$ git status
# On branch master
nothing to commit, working directory clean

108. end-part1
HEAD
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting
6fba518
Initial Commit

109. HEAD
end-part1
master
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting
6fba518
Initial Commit

110. HEAD
end-part1
master
in other version control
systems, master is called
trunk
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting
6fba518
Initial Commit

111. Create a branch
$ git branch testing

112. HEAD
end-part1
master
7c57165
Create 2 files in a single commit
e642771
Make hello.txt more exciting
6fba518
Initial Commit

113. HEAD
master
testing
7c57165
e642771
6fba518
end-part1

114. Switch to branch
$ git checkout testing
Switched to branch 'testing'
$ git status
# On branch testing
nothing to commit, working directory clean

115. HEAD
master
testing
7c57165
e642771
6fba518
end-part1

116. HEAD
master
testing
7c57165
e642771
6fba518
end-part1

117. Commit to new branch
Modify "names.txt" to add "Eve":
Alice
Bob
Cindy
Eve

118. Commit to new branch
$ git commit -am "Add Eve"
[testing cdd47c2] Add Eve
1 file changed, 1 insertion(+)
$ gitk

119. HEAD
master
testing
7c57165
e642771
6fba518
end-part1

120. HEAD
cdd47c2
testing
master
7c57165
e642771
6fba518
end-part1

121. HEAD
cdd47c2
master
7c57165
e642771
6fba518
end-part1
testing

122. Switch back to master
$ git checkout master
Switched to branch 'master'

123. HEAD
cdd47c2
master
7c57165
e642771
6fba518
end-part1
testing

124. HEAD
cdd47c2
master
7c57165
e642771
6fba518
end-part1
testing

125. Difference between log --all
vs normal log
$ gitk

126. HEAD
master
7c57165
e642771
6fba518
end-part1

127. Difference between log --all
vs normal log
$ gitk --all

128. HEAD
cdd47c2
master
7c57165
e642771
6fba518
end-part1
testing

129. Commit to master
Modify "names.txt" to add "Billy":
Alice
Billy
Bob
Cindy
$ git commit -am "Add Billy"
[master cc3044c] Add Billy
1 file changed, 1 insertion(+)

130. HEAD
cdd47c2
master
7c57165
e642771
6fba518
end-part1
testing

131. HEAD
master
cc3044c
7c57165
e642771
6fba518
cdd47c2
end-part1
testing

132. Shortcut: create and switch
$ git checkout -b testing2
Switched to branch 'testing2'

133. HEAD
master
cc3044c
7c57165
e642771
6fba518
cdd47c2
end-part1
testing

134. HEAD
master
testing2
cc3044c
7c57165
e642771
6fba518
cdd47c2
end-part1
testing

135. Commit to testing2
Modify "names.txt" to add "Dave":
Alice
Billy
Bob
Cindy
Dave
$ git commit -am "Add Dave"
[testing2 80414cf] Add Dave
1 file changed, 1 insertion(+)

136. HEAD
master
testing2
cc3044c
7c57165
e642771
6fba518
cdd47c2
end-part1
testing

137. testing2
HEAD
80414cf
master
cc3044c
7c57165
e642771
6fba518
cdd47c2
end-part1
testing

138. yay, mukha nang puno

139. Go back to master
$ git checkout master
Switched to branch 'master'
$ gitk --all

140. testing2
HEAD
80414cf
master
cc3044c
7c57165
e642771
6fba518
cdd47c2
end-part1
testing

141. Merge another branch
$ git merge testing
Auto-merging names.txt
Merge made by the 'recursive' strategy.
names.txt | 1 +
1 file changed, 1 insertion(+)

142. testing2
HEAD
80414cf
master
cc3044c
7c57165
e642771
6fba518
cdd47c2
end-part1
testing

143. master
testing2
80414cf
f56f4fa
cc3044c
7c57165
e642771
6fba518
HEAD
Merge branch 'testing'
cdd47c2
end-part1
testing

144. Merge Conflict
$ git merge testing2
Auto-merging names.txt
CONFLICT (content): Merge conflict in names.txt
Automatic merge failed; fix conflicts and then
commit the result.

145. Merge Conflict
Open names.txt:
Alice
Billy
Bob
Cindy
<<<<<<< HEAD
Eve
=======
Dave
>>>>>>> testing2

146. Merge Conflict
Open names.txt:
Alice
Billy
Bob
Cindy
<<<<<<< HEAD
Eve
=======
Dave
>>>>>>> testing2
version from HEAD i.e master

147. Merge Conflict
Open names.txt:
Alice
Billy
Bob
Cindy
<<<<<<< HEAD
Eve
=======
Dave
>>>>>>> testing2
version from testing2

148. Resolving Merge Conflict
Edit names.txt removing the markers:
Alice
Billy
Bob
Cindy
Dave
Eve

149. Resolving Merge Conflict
Commit the resolved merge conflict
$ git commit -am "Merge branch 'testing2' and fix
conflict"
[master 07e83b3] Merge branch 'testing2' and fix
conflict

150. master
testing2
80414cf
f56f4fa
cc3044c
7c57165
e642771
HEAD
Merge branch 'testing'
cdd47c2
end-part1
testing

151. master
HEAD
07e83b3
Merge branch 'testing2' and fix conflict
f56f4fa
Merge branch 'testing'
testing2
80414cf
cc3044c
7c57165
e642771
cdd47c2
end-part1
testing

152. Another way to merge:
Rebasing

153. Working on two branches
$ git checkout -b merging-demo
Switched to a new branch 'merging-demo'

154. Commit to merging-demo
Modify "names.txt" to remove "Alice":
Billy
Bob
Cindy
Dave
Eve
$ git commit -am "Remove Alice"
[merging-demo 00b26cb] Remove Alice
1 file changed, 1 deletion(-)

155. Commit to merging-demo
Modify "names.txt" to remove "Cindy":
Billy
Bob
Dave
Eve
$ git commit -am "Remove Cindy"
[merging-demo b115e79] Remove Cindy
1 file changed, 1 deletion(-)

156. Switch back to master
$ git checkout master
Switched to branch 'master'

157. Commit to master
Modify "numbers.txt" to remove "8.2":
3
9
16
12
4
$ git commit -am "Remove 8.2"
[master 0c1f192] Remove 8.2
1 file changed, 1 deletion(-)

158. Commit to master
Modify "numbers.txt" to remove "9":
3
16
12
4
$ git commit -am "Remove 9"
[master bc3583d] Remove 9
1 file changed, 1 deletion(-)

159. merging-demo
master
b115e79
00b26cb
bc3583d
0c1f192
07e83b3
HEAD

160. Merging
master
merging-demo
aff102e
b115e79
00b26cb
bc3583d
0c1f192
07e83b3
HEAD

161. Rebasing
$ git rebase merging-demo
First, rewinding head to replay your work on
top of it...
Applying: Remove 8.2
Applying: Remove 9

162. merging-demo
master
b115e79
00b26cb
bc3583d
0c1f192
07e83b3
HEAD

163. merging-demo
master
b115e79
00b26cb
HEAD
bc3583d
Remove 9
0c1f192
Remove 8.2
07e83b3

164. master
73dd819
Remove 9
67b81ce
Remove 8.2
merging-demo
b115e79
00b26cb
07e83b3
HEAD

165. master
73dd819
67b81ce
merging-demo
Remove 9
Remove 8.2
b115e79
00b26cb
07e83b3
HEAD

166. Later na lang yung
merge vs rebase

167. Malapit na tayo mag-Github,
but first...

168. Remote Repositories

169. Clone into another folder
$ cd ..
$ git clone devcon-git101 git101
Cloning into 'git101'...
done.

170. Check the clone repo
$ cd git101
$ gitk

171. HEAD
HEAD
master
master
merging-demo
/devcon-git101
merging-demo
/git101

172. remotes/origin/
master
HEAD
master
master
remotes/origin/
merging-demo
merging-demo
/devcon-git101
merging-demo
/git101
HEAD

173. Show remote repos
$ git remote
origin

174. "origin" remote repo
(default repo referring to the repo's origin)
$ git remote show origin
* remote origin
Fetch URL: c:/Users/user/devcon-git101
Push URL: c:/Users/user/devcon-git101
HEAD branch: master
Remote branches:
master
tracked
merging-demo tracked
testing
tracked
testing2
tracked
Local branch configured for 'git pull':
master merges with remote master
Local ref configured for 'git push':
master pushes to master (up to date)

175. remotes/origin/
master
HEAD
master
/devcon-git101
master
/git101
HEAD

176. Synchronizing with
Remote Repos

177. Fetching demo
Go back to /devcon-git101 (either open a new terminal/Git Bash
window) and modify "names.txt" to add Greg:
Billy
Bob
Dave
Eve
Greg
$ git commit -am "Add Greg"
[master cf5f902] Add Greg
1 file changed, 1 insertion(+)

178. remotes/origin/
master
HEAD
master
/devcon-git101
master
/git101
HEAD

179. HEAD
remotes/origin/
master
master
master
/devcon-git101
/git101
HEAD

180. Fetching demo
Go back to git101 and fetch the changes:
$ cd ../git101
$ git fetch
remote: Counting objects: 5, done.
remote: Compressing objects: 100% (2/2), done.
remote: Total 3 (delta 0), reused 0 (delta 0)
Unpacking objects: 100% (3/3), done.
From c:/Users/user/devcon-git101
73dd819..cf5f902 master
-> origin/master

181. HEAD
remotes/origin/
master
master
master
/devcon-git101
/git101
HEAD

182. remotes/origin/
master
HEAD
master
master
/devcon-git101
/git101
HEAD

183. Merge the fetched branch
$ git merge origin/master
Updating 73dd819..cf5f902
Fast-forward
names.txt | 1 +
1 file changed, 1 insertion(+)

184. remotes/origin/
master
HEAD
master
master
/devcon-git101
/git101
HEAD

185. A fast-forward occurs when you merge a
branch which has HEAD as an ancestor.
In this case, only the references are affected.
remotes/origin/
master
HEAD
master
master
/devcon-git101
/git101
HEAD

186. Shortcut
$ git fetch
$ git merge origin/master
is equivalent to
$ git pull
if you're in master branch.
We'll discuss more of this later.

187. Now that we understand the
basic idea behind remote repos,
let's proceed to Github...
Sign-up at https://github.com

188. There are multiple ways to
authenticate users in Git.
We'll discuss the most secure
one: via SSH keys.

189. Cryptography pasakalye...

190. Authentication via Password
Client
Server

191. Authentication via Password
username + password
Client sends
credentials
Server verifies
password
DB

192. Authentication via Password
username + password
Client sends
credentials
can be intercepted
e.g. FTP
Server verifies
password
DB

193. Authentication via SSH Key
(oversimplified)
Client has 2 "keys"
private key
public key
Server

194. Authentication via SSH Key
(oversimplified)
Client has 2 "keys"
private key
public key
Server has a list of
authorized keys

195. Authentication via SSH Key
(oversimplified)
First, the public key must be sent to the server securely beforehand.
Client has 2 "keys"
private key
public key
Server has a list of
authorized keys

196. Authentication via SSH Key
(oversimplified)
Using the private key, client can create a package that
can only be unlocked by the corresponding public key
and only that public key.
Client
private key
public key
Server has a list of
authorized keys

197. Authentication via SSH Key
(oversimplified)
Using the private key, client can create a package that
can only be unlocked by the corresponding public key
and only that public key.
Client
private key
public key
Server has a list of
authorized keys

198. Authentication via SSH Key
(oversimplified)
Using the private key, client can create a package that
can only be unlocked by the corresponding public key
and only that public key.
Client
private key
public key
Server has a list of
authorized keys

199. Authentication via SSH Key
(oversimplified)
Using the private key, client can create a package that
can only be unlocked by the corresponding public key
and only that public key.
Client
private key
public key
doesn't matter if
intercepted since
they still need to
crack it.
Server has a list of
authorized keys

200. How to generate your SSH Keys:
https://help.github.com/articles/generating-ssh-keys
Also, follow the steps to add your public
key to Github.

201. If you want to be secure, use a
passphrase.
However, if you're using Windows, you
will need to enter it every time you run
a git command that connects to Github.

202. Fortunately, there is a workaround
that will only require you to enter it
once per session.
http://stackoverflow.com/a/9011152

203. Create a repo in Github for
devcon-git101
https://github.com/new

204. Pushing devcon-git101
Go back to devcon-git101 and push it to your new repo (use SSH url)
$ git remote add origin git@github.com:user/devcon-git101.git
$ git push -u origin master
Warning: Permanently added the RSA host key for IP address
'192.30.252.130' to the list of known hosts.
Enter passphrase for key '/c/Users/user/.ssh/id_rsa':
Counting objects: 40, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (24/24), done.
Writing objects: 100% (40/40), 3.41 KiB, done.
Total 40 (delta 3), reused 0 (delta 0)
To git@github.com:user/devcon-git101.git
* [new branch]
master -> master
Branch master set up to track remote branch master from origin.

205. git push
Note that "git push" only pushes a single branch.
If you want to push all branches you can use:
$ git push REMOTE --all
If you want to push all tags you can use:
$ git push REMOTE --tags

206. Clone into another folder
$ cd ..
$ git clone git@github.com:user/devcon-git101.git github-git101
Cloning into 'github-git101'...
remote: Counting objects: 40, done.
remote: Compressing objects: 100% (21/21), done.
remote: Total 40 (delta 3), reused 40 (delta 3)
Receiving objects: 100% (40/40), done.
Resolving deltas: 100% (3/3), done.
done.

207. play time
With the cloned folder, you can now play around with certain
collaboration scenarios. For example:
1. Make some changes in /devcon-git101
2. Commit it via "git commit"
3. Push it to the repo at Github via "git push"
4. Go to /github-git101 and pull the changes via "git pull"

208. Want to let someone else push to
your repo?
Go to the repo Settings →
Collaborators and add your friends.

209. Push/Pull
You'll quickly notice that git push only allows
fast-forward changes to be pushed.
In simpler terms, you cannot push until you pull
the latest changes from the remote.

210. pull + rebase
Want to get rid of the distracting merge commits
whenever you pull when you have pending
commits? Tell git to rebase instead of merging:
$ git pull --rebase origin master

211. Best Practices

212. merge vs rebase
The problem with rebase is that you can overwrite
commits already on the remote repository and this can
affect your team.
That said, people generally use rebase when working
together on a single branch (e.g. git pull --rebase
origin master) and merge when merging branches.

213. Project Workflow
Here's the most basic workflow for working with with others
through version control systems:
1. Double check if the project work e.g. compiles, pages load, etc.
2. Stage and commit your changes.
3. Before pushing, pull changes from the remote project repo. If
there are no changes, skip to step 5.
4. Resolve conflicts, if any, then go back to step 1.
5. Push your changes.

214. Communicate!
Version control systems aims to improve communication
between team members, not replace it.
Always consult with the other person whenever
you encounter a merge conflict.

215. Broken Builds
To repeat step 1:
1. Double check if the project work e.g. compiles, pages load, etc.
Broken builds are what we call published commits that have
obvious critical, show-stopping bugs.
That said, it's better to delay pushing your commits to spend
more time making sure that the project works rather than waste
everyone's time.

216. Work in Progress
Avoid publishing half-done work as it can lead to
broken builds.
If you need to push those changes (e.g. you want
a backup), put them in a branch then push that
branch. Or consider using git stash.

217. Helpful Stuff
that we will still not explain in detail...

218. Graphical Git Tools

219. Client - Server VCS
vs
Distributed VCS

220. Push-based
vs
Pull-based

221. Backups

222. GitHub as a Project
Management Tool

223. GitHub as a Project
Management Tool for
Open Source Projects

224. GitHub as a Portfolio

225. Branches + Workflow

226. Tagging + Deployment

227. Free Private Repos
Since Github is only free for public repos, you might want to
look into the following to keep your source code private:
Assembla (https://www.assembla.com)
- 1 private repo, limited to 3 collaborators
BitBucket (https://bitbucket.org/)
- Unlimited private repos, limited to 5 collaborators
Github Educational Accounts (https://github.com/edu)
- free accounts for students and teachers

228. Summary of Commands
git branch - list, create, or delete branches
git checkout - checkout a branch or a path
git merge - merge two or more branches
git rebase - move commits to the end of a branch
git clone - make a local copy of a repository
git remote - list, create, or delete remote repos
git fetch - retrieve objects/changes from a repository
git pull - fetch + merge or rebase
git push - publish local commits to a remote

229. Summary of Command
Variations
git checkout -b
- create and checkout branch
git remote add
- add a new remote repository to track
git remote rm
- remove remote repository
git pull --rebase
- rebase instead of merge when pulling

230. Commands that I use
everyday
git pull --rebase
git add
git commit -am "blah blah"
gitk / git log / git status / git diff
git push

231. Commands that I use less
often
git clone
git remote add
git remote -v
git checkout <branch>
git rebase <branch> / git merge <branch>
git checkout -- <path>
git reset --hard <hash>
git revert

232. Thank You For Listening!