Welcome to Code versioning using git

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Welcome toCode versioning using git

• March 24, 2015

Per Zetterberg School of Electrical Engineering
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code versioning systems
CVS, SVN, git, . purpose Keep track of created
textfiles (e.g. C code). Versions. Helps merge
changes by multiple users. We will use git
distributed versioning system but we will
used in a centralized manner
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The central repository github.com

• https//github.com/pzett/eq2440_2015
• All the code, all the commits, everything.
• What is on github is the backuped official state
  of the project.

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Git client git bash
Git GUI
Copy and paste text. Mark upper-left corner
(icon). From menu Edit-gtCopy
Edit-gtPaste
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Set up local repository (local copy)
From the git bash command line gtgit clone
https//github.com/pzett/eq2440_2015.git
eq2440_alice gtcd eq2440_alice gtgit config -local
user.email alice_at_kth.se gtgit config -local
user.name alice Import the project into
eclipse 1) File-gtImport-gtExisting Android Code
Into Workspace -gt Browse to blue_alice/FrameWork
and select it 2) Right click FrameWork Package
Explorer in eclipse -gt build path -gt source tab
-gtAdd folder - gt Mark External Src- gt OK OK
Reading http//toroid.org/ams/git-central-repo-
howto
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How we will work
Repository eq2440_2015
Alice Implements or changes file1.cpp and
file2.cpp Updates repository git add file1.cpp
file2.cpp git commit -m comment
Bob Implements or changes file1.hpp and
file2.hpp Updates repository git add file1.hpp
file2.hpp git commit -m comment
git push
git push
git pull
git pull
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Conflict resolution

• Alice and Bob have clean updated local
  repositories.
• Alice modifies her file1.cpp
• Bob modifies his file1.cpp
• Bob does
• git add file1.cpp
• git commit -m change initialization of i1
• git push
• Alice does
• git add file1.cpp
• git commit -m I changed initialization of i1
  to 2
• git push
• Alice gets message
• error failed to push some refs to
  'https//github.com/pzett/blue.git'
• hint Updates were rejected because the remote
  contains work that you do
• .
• CONFLICT (content) Merge conflict in file1.cpp
• Automatic merge failed fix conflicts and then
  commit the result.

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Conflict resolution continued

• Alice gt git pull
• Auto-merging FrameWork/src/se/kth/android/StudentC
  ode/file2.txt
• CONFLICT (content) Merge conflict in
  FrameWork/src/se/kth/android/
• file2.txt
• Automatic merge failed fix conflicts and then
  commit the result.
• Alice opens file1.cpp
• ltltltltltltlt HEAD
• i12
• I11
• gtgtgtgtgtgtgt 55f223d4ab24ae40f19ae551d51205b69a23177e
• Alice and Bob discusses and finds that Alice was
  right.
• Alice removes Bobs code and pushes it.
• Alicegt git add file1.cpp
• Alicegt git commit -F .git/MERGE_MSG
• Alicegt git push
• Bobgt git pull

Alice's code
Bob's code
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Exercise 1 Little red riding hood

• git clone https//github.com/pzett/test.git
  test_yourname
• Create file with name riding_hood.txt
• Insert your text one section at a time.
• Push result after each added section.
• Look at previous slides.
• You can look at the progress on web site
• https//github.com/pzett/test

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Branching
C0
C2
C1
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Branching
C0
C2
C1
C3
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Branching
C0
C2
C1
C3
C4
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Branching commands

• gtgit branch new_idea
• gtgit branch
• master
• new_idea
• gt git checkout new_idea
• gt git push --set-upstream origin new_idea

Let there be a new branch in the Local repository
List available branches.
This is the branch we are currently on.
Switch to the new branch.
Create a corresponding branch in the repository.
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Merge without conflict
Some work done and added and commited and pushed
on both branches.
Merging in new_idea into master gtget checkout
master gtgit merge new_idea Updating
37fb5f2..663442c Fast-forward FrameWork/src/se/kt
h/android/StudentCode/test.txt 1 1 file
changed, 1 insertion()
gt git push
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Merge (with conflict)
Some work done and added and commited and pushed
on both branches.
Merging in new_idea into master gtgit checkout
master gtgit merge new_idea Auto-merging
FrameWork/src/se/kth/android/StudentCode/test.txt
CONFLICT (content) Merge conflict in
FrameWork/src/se/kth/androi Automatic merge
failed fix conflicts and then commit the result.
Open test.txt and manually edit it as you want
it. gt git add test.txt gt git commit -F
.git/MERGE_MSG gt git push
Generates default merge message.
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Merge with branch on repository
gtgit merge origin/new_idea Then proceed as the
previous branch
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Exercise 2 Little red riding hood

• Create a personal branch and push it to the
  server.
• Interpolate (i.e. add more text) to the places
  marked in your version of riding_hood.txt push
  each section to the server.
• When all are done merge with the versions of the
  other students and make a meaningful text.

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Warning dont use stash (generally)

• gtgit pull
• error Your local changes to the following files
  would be overwritten by checkout
• riding_hood.txt
• Please, commit your changes or stash them before
  you can switch branches.
• Aborting
• Instead you should do
• git add riding_hood.txt
• git commit m Meaningful message
• git push
• Then try git pull.