IASA presentation of Git talk

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

2. DVCS

3. What? Why?
Basic Use
DVCS

4. What? Why?
Basic Use
Who’s Theory
DVCS Using Git?
Deeper
Use

5. What? Why?
Basic Use
Who’s Theory
DVCS Using Git?
Deeper
Use
Usage Models
GUIs High Points

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

7. contrasts

16. otistical bastard, and
“
I'm an eg
I name all my projects
after myself. Fi rst Linux,
now git. ”
-Lin us Torvalds

17. otistical bastard, and
“
I'm an eg
I name all my projects
after myself. Fi rst Linux,
now git. ”
-Lin us Torvalds

19. RCS
Folders

20. Clear
Source Case
Safe
CVS
PVCS
RCS
Folders

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

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

23. t
Source Code Control
Gi

24. Gi
Source Code Control
t

25. CultureChange

30. Centralized
VCS =Don’t

31. Centralized
VCS =Don’t

32. Distributed
VCS = Whatever!
Do

33. Innovate

34. Experiment

35. Safely Be Wrong

36. Drive-by Assist

37. Crowd Source

38. Crowd Source

39. Crowd Source

41. Just show it to me!

43. No, not on that!

45. Download binaries

46. Git Distro Sources
Win Cygwin
Win msysGit

47. Git Distro Sources
Win Cygwin
Win msysGit
Linux Source
Linux Package manager

48. Git Distro Sources
Win Cygwin
Win msysGit
Linux Source
Linux Package manager
Mac MacPorts
Mac git-osx-installer

49. Git Distro Sources
Win Cygwin
Win msysGit
Linux Source
Linux Package manager
Mac MacPorts
Mac git-osx-installer
Any JGit

50. Put it in your path

52. Identify yourself

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

54. Global Git Settings
git config --list

55. Global Git Settings
git config --list
t va lues
t cu rren
Outpu

56. Use it!

57. Creating a Repo
mkdir myproj.git

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

59. Creating a Repo
mkdir myproj.git
cd myproj.git
git init

60. Creating a Repo
!
mkdir myproj.git
D O N E
cd myproj.git
git init

61. Thanks
for attending!

62. Knobs and Dials

65. 145+ Commands

66. What? Why?
Basic Use
Who’s Theory
DVCS Using Git?
Deeper
Use
Usage Models
GUIs High Points

67. Who’s Got Git?

77. Follow the
DOTS

78. Symmetric

90. Symmetric

91. Distributed

98. pu
sh

99. pu
sh

102. push

103. push

106. pull

107. pull

109. Distributed

110. Hashes and
Integrity

111. Index vs Hash
‣ Centralized VCS uses DB
sequential index.
‣ Git uses SHA-1 hash.

112. SHA-1 Hash
‣ Hash for the sake of integrity.
‣ Keep the source of the hash.

113. SHA-1 Hash
‣ Hash for the sake of integrity.
‣ Keep the source of the hash.
ught
I tho ere
es w
hash r
fo
swo rds?
pas

114. Centralized VCS

115. Alice Bob

116. Alice Bob
1 = okay.htm

117. Alice Bob
1 = okay.htm
2 = fine.htm

118. Alice Bob
1 = okay.htm
2 = fine.htm svnsync

119. Alice Bob
1 = okay.htm 1 = okay.htm
2 = fine.htm svnsync 2 = fine.htm

120. Alice Bob
1 = okay.htm 1 = okay.htm
2 = fine.htm svnsync 2 = fine.htm
3 = good.htm

121. Alice Bob
1 = okay.htm 1 = okay.htm
2 = fine.htm svnsync 2 = fine.htm
3 = good.htm
3 = great.htm

122. Alice Bob
1 = okay.htm 1 = okay.htm
2 = fine.htm svnsync 2 = fine.htm
3 = good.htm
3 = great.htm svnsync

123. Alice Bob
1 = okay.htm 1 = okay.htm
2 = fine.htm svnsync 2 = fine.htm
4 = good.htm 3 = good.htm
3 = great.htm svnsync 4 = great.htm

124. Alice Bob
1 = okay.htm 1 = okay.htm
2 = fine.htm svnsync 2 = fine.htm
ERROR
4 = good.htm 3 = good.htm
3 = great.htm ERROR
svnsync 4 = great.htm

125. Distributed VCS

126. Alice Bob

127. Alice Bob
a233b76 = okay.htm

128. Alice Bob
a233b76 = okay.htm
d234ab1 = fine.htm

129. Alice Bob
a233b76 = okay.htm
d234ab1 = fine.htm Sync

130. Alice Bob
a233b76 = okay.htm a233b76 = okay.htm
d234ab1 = fine.htm Sync d234ab1 = fine.htm

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

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

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

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

135. Hashable Objects
‣ Blob
‣ Tree
‣ Commit
‣ Tag

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

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

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

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

140. Hash Benefits
Independence
‣ Time & location separation from sequence # of
checkin.
‣ Easy merging of repositories
‣ Easy identification of what needs to be synced

141. Hash Benefits
Integrity
‣ Identifies damaged repos.
‣ Prevents modification of published history.
‣ Unique to file size and contents.

142. Hash Benefits
Tags
‣ Cryptographically sign tags by GPG.
‣ Guaranteeing the repo’s state at a point
in time.

143. Location,Location,Location

144. Single Stage Thinking
of Subversion

145. Subversion
‣ svn commit
‣ Adds everything modified.
‣ “committed” locally and on the server.
‣ Must list if you want specific files.
‣ What if you check in your password?

146. $ echo //COMMENTS >> Matt1.java
$ echo //THOUGHTS >> Matt2.java

147. $ echo //COMMENTS >> Matt1.java
$ echo //THOUGHTS >> Matt2.java
$ svn status
M Matt1.java
M Matt2.java

148. $ echo //COMMENTS >> Matt1.java
$ echo //THOUGHTS >> 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.

149. Three Stage Thinking
of Git

150. 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.

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

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

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

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

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

156. Remote
is like a special
Stash
Repo
Index
Working

157. Remote
is like a special
Stash
Repo
Index
Working

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

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

160. Remote
is like a special
Stash
Repo
git clone
git checkout
edit experiment files
Index
Working

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

162. Remote
is like a special
Stash
Repo
git clone
git checkout
edit experiment files
git stash
test buggy files
Index
Working

163. Remote
is like a special
Stash
Repo
git clone
git checkout
edit experiment files
git stash
test buggy files
Index git stash apply
Working

164. Remote
is like a special
Stash
Repo
git clone
git checkout
edit experiment files
git stash
test buggy files
Index git stash apply
Working git add

165. Remote
is like a special
Stash
Repo
git clone
git checkout
edit experiment files
git stash
test buggy files
Index git stash apply
Working git add
git commit

166. Remote
is like a special
Stash
Repo
git clone
git checkout
edit experiment files
git stash
test buggy files
Index git stash apply
Working git add
git commit
git push

167. Remote
is like a special
Stash
Repo
git clone
git checkout
edit experiment files
git stash
test buggy files
Index git stash apply
Working git add
git commit
git push

168. What does this buy me?

169. $ echo //MYD0GSNAM3 >> mattfile1.txt
$ echo //NewText2 >> mattfile2.txt

170. $ echo //MYD0GSNAM3 >> mattfile1.txt
$ echo //NewText2 >> mattfile2.txt
$ git status
# On branch master
# Changed but not updated:
# modified: mattfile1.txt
# modified: mattfile2.txt

171. $ echo //MYD0GSNAM3 >> mattfile1.txt
$ echo //NewText2 >> mattfile2.txt
$ git status
# On branch master
# Changed but not updated:
# modified: mattfile1.txt
# modified: mattfile2.txt
o in dex
int
$ git add mattfile1.txt Put

172. $ echo //MYD0GSNAM3 >> mattfile1.txt
$ echo //NewText2 >> mattfile2.txt
$ git status
# On branch master
# Changed but not updated:
# modified: mattfile1.txt
# modified: mattfile2.txt
o in dex
int
$ git add mattfile1.txt Put
to r epo
S ave
$ git commit -m'Matts pw checkin'
[master]: created ddcdf18: quot;Matts pw checkinquot;
1 files changed, 1 insertions(+), 0 deletions(-)

173. #$%^&!
I just committed my password!

174. 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

175. Change History
com mit
the
w a way
$ git reset --hard HEAD^ T hro
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

176. Change History
com mit
the
w a way
$ git reset --hard HEAD^ T hro
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

177. Sharing

178. Serving It Up
Protocols
‣ GIT
‣ SSH
‣ SCP
‣ Local file system
‣ SAMBA
‣ HTTP
‣ WebDAV
‣ rsync

179. 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.

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

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

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

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

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

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

188. Merge & Rebase

189. Cheap Branches

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

191. Merge Anything

192. 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

193. Rebase for Clarity

194. 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.
‣Reposition your feature branch’s start point.
‣Makes for simpler merge graphs.

195. M
da
S er
r
ta g
d
n e
Master/Trunk/MainLatest

196. M
da
S er
r
ta g
d
n e
Master/Trunk/MainLatest
a32

197. ard Bra
d
n e
ta g
a32 n ch
S er
Master/Trunk/MainLatest
M 2e2

198. ard Bra
d
n e
ta g
a32 n ch
S er
Master/Trunk/MainLatest
d19
M 2e2

199. ard Bra
d
n e
ta g
a32 n ch
S er
Master/Trunk/MainLatest
d19
M 2e2
8b3

200. ard Bra
d
n e
ta g
a32 n ch
S er
Master/Trunk/MainLatest
d19
M 2e2
e69
8b3

201. ard Bra
d
n e
ta g
a32 n ch
S er
Master/Trunk/MainLatest
d19
M 2e2
e69
8b3
erge
M
9f1

202. Rebasing
Master/Trunk/MainLatest

203. Rebasing
Master/Trunk/MainLatest
a32

204. Rebasing
Master/Trunk/MainLatest
a32
2e2
Bra
ch n

205. Bra
sing a32
n ch
ba
Master/Trunk/MainLatest
Re 2e2 d19

206. Bra
sing a32
n ch
ba
Master/Trunk/MainLatest
Re 2e2 d19
8b3

207. Bra
sing a32
n ch
ba
Master/Trunk/MainLatest
Re 2e2 d19
8b3
e69

208. Master/Trunk/MainLatest
a32
2e2
8b3
Bra
ch n
d19
e69
Rebase

209. a32
Master/Trunk/MainLatest
2e2
8b3 Bra
n ch
d19 d19
Me
rg
e
e69 e69

210. WorkingOffline

211. Offline Anything
Checkin

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

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

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

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

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

218. Speed

219. git: git
hg: mercurial
bzr: bazaar

220. 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

222. 10
to
100 times
Faster

223. VCS Interop

224. Subversion
git svn clone http://unfurl.com/trunk
git svn dcommit

225. Subversion
git svn clone http://unfurl.com/trunk
git svn dcommit
‣ First class compatibility.

226. Subversion
git svn clone http://unfurl.com/trunk
git svn dcommit
‣ First class compatibility.
‣ Round trip support.

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

229. Migration
‣ git svn clone

230. Migration
‣ git svn clone
‣ Power off your Subversion server.

231. What? Why?
Basic Use
Who’s Theory
DVCS Using Git?
Deeper
Use
Usage Models
GUIs High Points

232. UsageModels

233. Centralized
Central
Repo

234. Centralized
Central
Repo

235. Repo
Blessed
Dictatorship

236. Repo
Blessed
Dictatorship

237. Repo
Blessed
Dictatorship

238. Repo
Blessed
Dictatorship

239. Repo
Blessed
Dictatorship

240. Certified
Integration Managed
Development
Repo Repo

241. Certified
Integration Managed
Development
Repo Repo

242. Certified
Integration Managed
Development
Repo Repo

243. Certified
Integration Managed
Development
Repo Repo

244. Mirror Mirror
Certified Development
Repo Repo
Mirrored

245. Mirror Mirror
Certified Development
Repo Repo
Mirrored

246. Mirror Mirror
Certified Development
Repo Repo
Mirrored

247. Mirror Mirror
Certified Development
Repo Repo
Mirrored

248. Mirror Mirror
Certified Development
Repo Repo
Mirrored

249. ☚ Private Public ☛
GitHub
Custom + Public Contrib

250. ☚ Private Public ☛
GitHub
Custom + Public Contrib

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

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

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

254. GUIs

255. GitX

256. GitSafe

257. GitK

258. GitGUI

259. EGit

261. ci a l !
O f fi
It ’s

263. 4
reasons

264. Cherry Pick
❹

265. Cherry Pick
❹

266. Cherry Pick
‣git
❹
cherry-pick a5b2ee

267. Cherry Pick
‣git
❹
cherry-pick a5b2ee
‣Merge in just one commit.

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

269. Bisect Bugs
❸

270. Bisect Bugs
❸

271. Bisect Bugs
‣git
❸
bisect run mvn test

272. Bisect Bugs
‣git
❸
bisect run mvn test
‣Binary-search for bug.

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

274. Squash Verbosity
❷

275. Squash Verbosity
❷

276. Squash Verbosity
❷
‣git merge --squash mybranch

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

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

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

280. Search History
❶

281. Search History
❶

282. Search History
‣git
❶
grep SomeText HEAD^^^

283. Search History
‣git
❶
grep SomeText HEAD^^^
‣Search in file history without checkout.

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

287. emerging Control
Version

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

289. 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

290. 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

291. 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

292. 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/