An updated introduction to the Git Distributed Version Control System. Be prepared to have everything you know about centralized VCS systems turned upside down, but all for the benefit of easy of use, better team-mate interactions, and more robust (guaranteed) repository integrity and uptime.

1. Git going
DVCS
with
n bending
mental spoo
minutes of
90
ode control
ia source c
v
by Matthew McCullough of Ambient Ideas, LLC

2. “ Git
-noun sant or
unplea
Slang. an
British
”
per son
emptible
cont
ionar y
rd English Dict
-Oxfo

5. astard, and
otistical b
“
I'm an eg
projects
all my
I name
yself. Fi rst Linux,
after m
git. ”
now
us Torvalds
-Lin

7. RCS
Folders

8. Clear
Source Case
Safe
CVS
PVCS
RCS
Folders

9. Subversion
BitKeeper
Perforce
Clear
Source Case
Safe
CVS
PVCS
RCS
Folders

10. darcs
Mercurial
Bazaar
Subversion
BitKeeper
Perforce
Clear
Source Case
Safe
CVS
PVCS
RCS
Folders

11. t
Source Code Control
Gi

12. Gi
Source Code Control
t

13. CultureChange

22. =Don’t
Centralized
VCS

23. Innovate

24. Experiment

25. Safely Be Wrong

26. Drive-by Assist

27. Crowd Source

31. Global Git Settings
git config --global user.name quot;Hal Smithquot;

32. Global Git Settings
git config --global user.name quot;Hal Smithquot;
git config --global user.email quot;hal@bnl.comquot;

33. Global Git Settings
git config --global user.name quot;Hal Smithquot;
git config --global user.email quot;hal@bnl.comquot;
ues
val
ent
urr
tc
tpu
Ou
git config --list

34. Creating a Repo
mkdir myproj.git

35. Creating a Repo
mkdir myproj.git
cd myproj.git

36. Creating a Repo
mkdir myproj.git
cd myproj.git
lks!
t fo
’s i
hat
git init T

39. Who’s Got Git?

46. Hashes and
Integrity

47. SHA-1 Hash
Index vs. Hash
‣ Centralized VCS uses DB auto-increment index.
‣ Git uses SHA-1 hash.
‣ Hash for the sake of integrity.
Hashable Objects
‣ Blob
‣ Tree
‣ Commit
‣ Tag

48. SHA-1 Hash
Index vs. Hash
‣ Centralized VCS uses DB auto-increment index.
‣ Git uses SHA-1 hash.
‣ Hash for the sake of integrity.
Hashable Objects ght
hou
It ere
‣ Blob es w
ash
h
‣ Tree
for
rds?
‣ Commit
swo
pas
‣ Tag

49. http://book.git-scm.com/1_the_git_object_model.html

50. http://book.git-scm.com/1_the_git_object_model.html

51. http://book.git-scm.com/1_the_git_object_model.html

52. http://book.git-scm.com/1_the_git_object_model.html

54. alized
entr
C
Alice Bob

55. alized
entr
C
Alice Bob
1 = okay.htm

56. alized
entr
C
Alice Bob
1 = okay.htm
2 = fine.htm

57. alized
entr
C
Alice Bob
1 = okay.htm
2 = fine.htm Sync

58. alized
entr
C
Alice Bob
1 = okay.htm 1 = okay.htm
2 = fine.htm 2 = fine.htm
Sync

59. alized
entr
C
Alice Bob
1 = okay.htm 1 = okay.htm
2 = fine.htm 2 = fine.htm
Sync
3 = good.htm

60. alized
entr
C
Alice Bob
1 = okay.htm 1 = okay.htm
2 = fine.htm 2 = fine.htm
Sync
3 = good.htm
3 = great.htm

61. alized
entr
C
Alice Bob
1 = okay.htm 1 = okay.htm
2 = fine.htm 2 = fine.htm
Sync
3 = good.htm
Sync
3 = great.htm

62. alized
entr
C
Alice Bob
1 = okay.htm 1 = okay.htm
2 = fine.htm 2 = fine.htm
Sync
4 = good.htm 3 = good.htm
Sync
3 = great.htm 4 = great.htm

63. alized
entr
C
Alice Bob
1 = okay.htm 1 = okay.htm
2 = fine.htm 2 = fine.htm
Sync
ERROR
4 = good.htm 3 = good.htm
ERROR
Sync
3 = great.htm 4 = great.htm

65. Distributed
Alice Bob

66. Distributed
Alice Bob
a233b76 = okay.htm

67. Distributed
Alice Bob
a233b76 = okay.htm
d234ab1 = fine.htm

68. Distributed
Alice Bob
a233b76 = okay.htm
d234ab1 = fine.htm Sync

69. Distributed
Alice Bob
a233b76 = okay.htm a233b76 = okay.htm
d234ab1 = fine.htm d234ab1 = fine.htm
Sync

70. Distributed
Alice Bob
a233b76 = okay.htm a233b76 = okay.htm
d234ab1 = fine.htm d234ab1 = fine.htm
Sync
f90b12c = good.htm

71. Distributed
Alice Bob
a233b76 = okay.htm a233b76 = okay.htm
d234ab1 = fine.htm d234ab1 = fine.htm
Sync
f90b12c = good.htm
ae42ba0 = great.htm

72. Distributed
Alice Bob
a233b76 = okay.htm a233b76 = okay.htm
d234ab1 = fine.htm d234ab1 = fine.htm
Sync
f90b12c = good.htm
Sync
ae42ba0 = great.htm

73. Distributed
Alice Bob
a233b76 = okay.htm a233b76 = okay.htm
d234ab1 = fine.htm d234ab1 = fine.htm
Sync
f90b12c = good.htm f90b12c = good.htm
Sync
ae42ba0 = great.htm ae42ba0 = great.htm

74. Hash Benefits
Integrity
‣ Identifies damaged repos.
‣ Prevents modification of published history.
‣ Unique to file size and contents.
Tags
‣ Cryptographically sign tags by GPG/email.
Independence
‣ Separation from sequence # of checkin.

75. Location,Location,Location

76. Single Stage Thinking
Subversion
svn commit
‣
‣ Adds everything modified.
‣ Must list if you want specific files.
‣ What if you check in your password?

77. $ echo //password >> Matt1.java
$ echo //password >> Matt2.java

78. $ echo //password >> Matt1.java
$ echo //password >> Matt2.java
$ svn status
M Matt1.java
M Matt2.java

79. $ echo //password >> Matt1.java
$ echo //password >> Matt2.java
$ svn status
M Matt1.java
M Matt2.java
$ svn commit -m'Matts checkin'
Adding Matt1.java
Adding Matt2.java
Transmitting file data .
Committed revision 2.

80. Remote
is like a special
Stash
Repo
Index
Working

81. Remote
is like a special
Stash
Repo
Index
Working

82. Remote
is like a special
Stash
Repo
git clone
Index
Working

83. Remote
is like a special
Stash
Repo
git clone
git checkout
Index
Working

84. Remote
is like a special
Stash
Repo
git clone
git checkout
edit some files
Index
Working

85. Remote
is like a special
Stash
Repo
git clone
git checkout
edit some files
git stash
Index
Working

86. Remote
is like a special
Stash
Repo
git clone
git checkout
edit some files
git stash
edit some files
Index
Working

87. Remote
is like a special
Stash
Repo
git clone
git checkout
edit some files
git stash
edit some files
Index git stash apply
Working

88. Remote
is like a special
Stash
Repo
git clone
git checkout
edit some files
git stash
edit some files
Index git stash apply
Working git add

89. Remote
is like a special
Stash
Repo
git clone
git checkout
edit some files
git stash
edit some files
Index git stash apply
Working git add
git commit

90. Remote
is like a special
Stash
Repo
git clone
git checkout
edit some files
git stash
edit some files
Index git stash apply
Working git add
git commit
git push

91. Remote
is like a special
Stash
Repo
git clone
git checkout
edit some files
git stash
edit some files
Index git stash apply
Working git add
git commit
git push

92. repo
uild
B
git clone git://somedomain/myproj.git
cd myproj.git

93. repo
uild
B
git clone git://somedomain/myproj.git
cd myproj.git
dex
te in
pda
U
git checkout master

94. repo
uild
B
git clone git://somedomain/myproj.git
cd myproj.git
dex
te in
pda
U
git checkout master
king
echo ‘//Comments’ >> ClassOne.java or
dit w
echo ‘//Thoughts’ >> ClassTwo.java E

95. repo
uild
B
git clone git://somedomain/myproj.git
cd myproj.git
dex
te in
pda
U
git checkout master
king
echo ‘//Comments’ >> ClassOne.java or
dit w
echo ‘//Thoughts’ >> ClassTwo.java E
ndex
to i
Add epo
git add ClassOne.java to r
ave
comments’ S
git commit -m’Added

96. repo
uild
B
git clone git://somedomain/myproj.git
cd myproj.git
dex
te in
pda
U
git checkout master
king
echo ‘//Comments’ >> ClassOne.java or
dit w
echo ‘//Thoughts’ >> ClassTwo.java E
ndex
to i
Add epo
git add ClassOne.java to r
ave
commit -m’Added comments’ S
git
ash
st
h to
stash Pus
git

97. Three Stage Thinking
Git
git add
‣
git commit
‣
git push
‣
‣ Commits only what is added to the index.
‣ Opportunity to change history locally.
‣ Selectively share with other repos.

98. $ echo //SECRETPASSWORD >> mattfile1.txt
$ echo //NewText2 >> mattfile2.txt

99. $ echo //SECRETPASSWORD >> mattfile1.txt
$ echo //NewText2 >> mattfile2.txt
$ git status
# On branch master
# Changed but not updated:
# modified: mattfile1.txt
# modified: mattfile2.txt

100. $ echo //SECRETPASSWORD >> mattfile1.txt
$ echo //NewText2 >> mattfile2.txt
$ git status
# On branch master
# Changed but not updated:
# modified: mattfile1.txt
# modified: mattfile2.txt
dex
o in
int
Put
$ git add mattfile1.txt

101. $ echo //SECRETPASSWORD >> mattfile1.txt
$ echo //NewText2 >> mattfile2.txt
$ git status
# On branch master
# Changed but not updated:
# modified: mattfile1.txt
# modified: mattfile2.txt
dex
o in
int
Put
$ git add mattfile1.txt
epo
to r
ave
S
$ git commit -m'Matts pw checkin'
[master]: created ddcdf18: quot;Matts changesquot;
1 files changed, 1 insertions(+), 0 deletions(-)

102. #$%^&!
I just committed my password!

103. Change History
$ git reset --hard HEAD^
HEAD is now at 9de4cd3 First checkin
$ git log
commit 9de4cd3a3f24a3de3e804df84cc3321c7d0c9993
Author: Matthew McCullough
<matthewm@ambientideas.com>
Date: Wed Mar 4 23:09:17 2009 -0700
First checkin

104. Change History
mit
com
the
way
wa
hro
T
$ git reset --hard HEAD^
HEAD is now at 9de4cd3 First checkin
$ git log
commit 9de4cd3a3f24a3de3e804df84cc3321c7d0c9993
Author: Matthew McCullough
<matthewm@ambientideas.com>
Date: Wed Mar 4 23:09:17 2009 -0700
First checkin

105. Change History
mit
com
the
way
wa
hro
T
$ git reset --hard HEAD^
HEAD is now at 9de4cd3 First checkin
$ git log
commit 9de4cd3a3f24a3de3e804df84cc3321c7d0c9993
Author: Matthew McCullough
<matthewm@ambientideas.com>
Date: Wed Mar 4 23:09:17 2009 -0700
First checkin

106. GitMathematics

107. Directed Acyclic Graph
a32
2e2
8b3
4e8

108. Directed Acyclic Graph
Ann’s Feature
a32 5fa
2e2
8b3
4e8

109. Directed Acyclic Graph
Ann’s Feature
a32 5fa
2e2
8b3
4e8

110. Directed Acyclic Graph
Ann’s Feature
a32 5fa
Tim’s Feature
2e2 d19
8b3
4e8

111. Directed Acyclic Graph
Ann’s Feature
a32 5fa
Tim’s Feature
2e2 d19
Linus’ rewrite of
Tim’s feature
8b3 e69
4e8

112. Directed Acyclic Graph
Ann’s Feature
a32 5fa
Tim’s Feature
2e2 d19
Linus’ rewrite of
Tim’s feature
8b3 e69
4e8

113. Sharing

114. Serving It Up
Network
‣ git instaweb. Built in, read-only, HTTP.
‣ git daemon. Custom socket language.
‣ gitosis. Easy permissions control.
‣ github. Open source & private repos.
‣ ssh. OS controlled permissions.

117. Serving It Up
Filesystem
‣ Local folders. Yes, they can be “remotes.”
‣ Mapped network drives. Just like folders.

118. on
aem
it d
g
git clone git://somehost.org/myproj.git

119. on
aem
it d
g
git clone git://somehost.org/myproj.git
SSH
git clone mccm06@somehost.org:myproj.git

120. on
aem
it d
g
git clone git://somehost.org/myproj.git
SSH
git clone mccm06@somehost.org:myproj.git
TTP
H
git clone http://somehost.org/myproj.git

121. on
aem
it d
g
git clone git://somehost.org/myproj.git
SSH
git clone mccm06@somehost.org:myproj.git
TTP
H
git clone http://somehost.org/myproj.git
tem
sys
File
git clone ~/work/myproj.git

122. on
aem
it d
g
git clone git://somehost.org/myproj.git
SSH
git clone mccm06@somehost.org:myproj.git
TTP
H
git clone http://somehost.org/myproj.git
tem
sys
File
git clone ~/work/myproj.git
rive
rk d
two
Ne
git clone z:someservermyproj.git

123. Merge & Rebase

124. Cheap Branches

125. Cheap Branches
git show-branch --all
git branch -a
‣Local branch
‣localbranchname
‣Remote
‣remote/branchname

126. Merge Anything

127. Merge Anything
git merge --no-commit <sourcebranch>
git merge --squash <sourcebranch>
git merge <sourcebranch1> <sourcebranch2>
‣Selectable merge strategy
‣Octopus: More than one
‣Review before committing
‣Flatten micro-checkins

128. Merge Strategies

129. Rebase for Clarity

130. Rebase for Clarity
git checkout myfeaturebranch
git rebase master
‣Cleaner history than a merge
‣Fast forwards original branch
‣Lets you see “how trunk will act” before you merge

131. WorkingOffline

132. Offline Anything
Checkin

133. Offline Anything
Checkin
Add
Branch
List change log
Grep history
Rewrite history
Stash
Merge
Label
Remove

134. Offline Anything
Checkin
Add
Branch
List change log
Grep history
Rewrite history
Stash
Merge
Label
Remove
practically everything but push

135. Offline Anything
Checkin
Add
Branch
List change log
Grep history
Rewrite history
Stash
Merge
Label
Remove
practically everything but push

137. Hooray! Another
checkin to my latest OSS
project!

138. Hooray! Another
checkin to my latest OSS
project!
I think I liked
subversion better...

139. Speed

140. Init Add Status Diff
Branch (Cold/Hot)
git hg bzr git hg bzr git hg bzr git hg bzr
Tag Log Commit (Lg) Commit (Sm)
git c git h hg c hg h bzr c bzr h
git hg bzr git hg bzr git hg bzr git hg bzr
data from http://whygitisbetterthanx.com/#git-is-fast

141. VCS Interop

142. Subversion
git svn clone http://unfurl.com/trunk
git svn dcommit
‣ First class compatibility.
‣ Round trip support.
‣ Git commits = svn commits.

144. UsageModels

145. Centralized
Central
Repo

146. Centralized
Central
Repo

147. Repo
Blessed
Dictatorship

148. Repo
Blessed
Dictatorship

149. Repo
Blessed
Dictatorship

150. Repo
Blessed
Dictatorship

151. Repo
Blessed
Dictatorship

152. Certified
Integration Managed
Development
Repo Repo

153. Certified
Integration Managed
Development
Repo Repo

154. Certified
Integration Managed
Development
Repo Repo

155. Certified
Integration Managed
Development
Repo Repo

156. Mirror Mirror
Certified Development
Repo Repo
Mirrored

157. Mirror Mirror
Certified Development
Repo Repo
Mirrored

158. Mirror Mirror
Certified Development
Repo Repo
Mirrored

159. Mirror Mirror
Certified Development
Repo Repo
Mirrored

160. Mirror Mirror
Certified Development
Repo Repo
Mirrored

161. ☚ Private Public ☛
GitHub
Custom + Public Contrib

162. ☚ Private Public ☛
GitHub
Custom + Public Contrib

163. ☚ Private Public ☛
Customized
GitHub
Custom + Public Contrib

164. ☚ Private Public ☛
Customized
GitHub
Custom + Public Contrib

165. ☚ Private Public ☛
Customized
GitHub
Custom + Public Contrib

166. GUIs

167. GitX

168. gitSafe

169. GitK

170. GitGUI

172. 6
reasons

173. Cherry Pick
❻
‣git cherry-pick a5b2ee

174. Cherry Pick
❻
‣git cherry-pick a5b2ee
‣Merge in just one commit.

175. Cherry Pick
❻
‣git cherry-pick a5b2ee
‣Merge in just one commit.
‣When you want a nugget, not a branchload.

176. Gives Credit
❺
‣Tracks who authors a change.

177. Gives Credit
❺
‣Tracks who authors a change.
‣“Author” even survives passing through reviewers.

178. Gives Credit
❺
‣Tracks who authors a change.
‣“Author” even survives passing through reviewers.
‣“Author” survives all merges.

179. Gives Credit
❺
‣Tracks who authors a change.
‣“Author” even survives passing through reviewers.
‣“Author” survives all merges.
‣Additionally tracks who committed a change.

180. Bisect Bugs
❹
‣git bisect run mvn test

181. Bisect Bugs
❹
‣git bisect run mvn test
‣Binary-search for bug.

182. Bisect Bugs
❹
‣git bisect run mvn test
‣Binary-search for bug.
‣Manual or automated modes.

183. Bisect Bugs
❹
‣git bisect run mvn test
‣Binary-search for bug.
‣Manual or automated modes.
‣Yak cruelty-prevention.

184. Squash Verbosity
❸
‣git merge --squash mybranch

185. Squash Verbosity
❸
‣git merge --squash mybranch
‣Reduce all your micro-checkins to block commits.

186. Squash Verbosity
❸
‣git merge --squash mybranch
‣Reduce all your micro-checkins to block commits.
‣Make mistakes, revise, checkin without hesitation.

187. Squash Verbosity
❸
‣git merge --squash mybranch
‣Reduce all your micro-checkins to block commits.
‣Make mistakes, revise, checkin without hesitation.
‣Great for SVN compatibility.

188. Search History
❷
‣git grep SomeText HEAD^^^

189. Search History
❷
‣git grep SomeText HEAD^^^
‣Search in file history without checkout.

190. Search History
❷
‣git grep SomeText HEAD^^^
‣Search in file history without checkout.
‣Greps contents.

191. Rebase
❶
‣git rebase master

192. Rebase
❶
‣git rebase master
‣Reposition your feature branch’s start point.

193. Rebase
❶
‣git rebase master
‣Reposition your feature branch’s start point.
‣Makes for simpler merge graphs.

194. Rebase
❶
‣git rebase master
‣Reposition your feature branch’s start point.
‣Makes for simpler merge graphs.
‣Sustains feature-branch work clarity.

196. Tomorrow’s VCS, Today

197. tthew
Ma
Twitter
@matthewmccull
Blog
http://www.ambientideas.com/blog
sidebar has all my social media links
Email
matthewm@ambientideas.com
GitHub
http://github.com/matthewmccullough

198. Resources
Git Homepage
http://git-scm.com
Directed Acrylic Graph
http://en.wikipedia.org/wiki/Directed_acyclic_graph
Git for Computer Scientists
http://eagain.net/articles/git-for-computer-scientists/
Git Treeish
http://book.git-scm.com/4_git_treeishes.html

199. Resources
Git Docs
http://www.kernel.org/pub/software/scm/git/docs/
Git Magic eBook
http://www-cs-students.stanford.edu/~blynn/gitmagic/book.pdf
Linus Torvald’s Git talk at Google
http://www.youtube.com/watch?v=4XpnKHJAok8
CygWin
http://www.cygwin.com

200. Resources
MSysGit
http://code.google.com/p/msysgit
Git Cheetah
http://code.google.com/p/msysgit/wiki/GitCheetah
Matthew’s Git Bookmarks
http://delicious.com/matthew.mccullough/git
Matthew’s Bash Prompt
http://gist.github.com/47267

201. Image Credits
‣ http://www.ambientideasphotography.com
‣ http://flickr.com/photos/lenore-m/2903856664/
‣ http://en.wikipedia.org/wiki/Git_(software)
‣ http://flickr.com/photos/karenhorton/1583513014/
‣ http://flickr.com/photos/mashdnart/2545782407/
‣ http://commons.wikimedia.org/wiki/
File:Small_Boy_nuclear_test_1962.jpg
‣ http://www.flickr.com/photos/knmurphy/2506896257/
‣ http://www.flickr.com/photos/albyspace/1022035568/
‣ http://flickr.com/photos/michaelhays/3070238360/
‣ http://flickr.com/photos/d_vdm/509996632/