Git Going With DVCS v1.3

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

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

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

RCS Folders

Clear Source Case Safe CVS PVCS RCS Folders

Subversion BitKeeper Perforce Clear Source Case Safe CVS PVCS RCS Folders

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

t Source Code Control Gi

Gi Source Code Control t

CultureChange

=Don’t Centralized VCS

Innovate

Experiment

Safely Be Wrong

Drive-by Assist

Crowd Source

Global Git Settings git conﬁg --global user.name \"Hal Smith\"

Global Git Settings git conﬁg --global user.name \"Hal Smith\" git conﬁg --global user.email \"hal@bnl.com\"

Global Git Settings git config --global user.name \"Hal Smith\" git config --global user.email \"hal@bnl.com\" ues val ent urr tc tpu Ou git config --list

Creating a Repo mkdir myproj.git

Creating a Repo mkdir myproj.git cd myproj.git

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

Who’s Got Git?

Hashes and Integrity

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

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

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

alized entr C Alice Bob

alized entr C Alice Bob 1 = okay.htm

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

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

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

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

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

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

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

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

Distributed Alice Bob

Distributed Alice Bob a233b76 = okay.htm

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

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

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

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

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

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

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

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.

Location,Location,Location

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

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

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

$ 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.

Remote is like a special Stash Repo Index Working

Remote is like a special Stash Repo git clone Index Working

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

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

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

$ 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

$ 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: \"Matts changes\" 1 files changed, 1 insertions(+), 0 deletions(-)

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

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

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

GitMathematics

Directed Acyclic Graph a32 2e2 8b3 4e8

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

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

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

Sharing

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.

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

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

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

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

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

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:\\someserver\\myproj.git

Merge & Rebase

Cheap Branches

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

Merge Anything

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

Merge Strategies

Rebase for Clarity

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

WorkingOffline

Offline Anything Checkin

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

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

Hooray! Another checkin to my latest OSS project!

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

Speed

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

VCS Interop

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

UsageModels

Centralized Central Repo

Repo Blessed Dictatorship

Certiﬁed Integration Managed Development Repo Repo

Mirror Mirror Certiﬁed Development Repo Repo Mirrored

☚ Private Public ☛ GitHub Custom + Public Contrib

☚ Private Public ☛ Customized GitHub Custom + Public Contrib

GUIs

GitX

gitSafe

GitK

GitGUI

6 reasons

Cherry Pick ❻ ‣git cherry-pick a5b2ee

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

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

Gives Credit ❺ ‣Tracks who authors a change.

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

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

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

Bisect Bugs ❹ ‣git bisect run mvn test

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

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

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

Squash Verbosity ❸ ‣git merge --squash mybranch

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

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

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.

Search History ❷ ‣git grep SomeText HEAD^^^

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

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

Rebase ❶ ‣git rebase master

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

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

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

Tomorrow’s VCS, Today

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

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

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

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

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/

Git Going With DVCS v1.3

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