Demonstrating rebasing and no-fast-forward merges in git

demo.sh

#!/bin/sh
mkdir temp
cd temp
git init
echo "a" > example-a.txt
echo "b" > example-b.txt
echo "c" > example-c.txt
git add .

git commit -am "First commit on master"
git checkout -b branch-a
git checkout -q master
git checkout -b branch-b

echo "\n\n"
echo "INITIAL STATE OF MASTER"
echo "========================================================================="
git checkout master >> /dev/null
git log --oneline --decorate --color | cat
echo "\n"

for I in 1 2 3
do
  git checkout -q branch-a >> /dev/null
  echo "a$I" > example-a.txt
  git commit -am "Commit $I, branch a" >> /dev/null
  git checkout -q branch-b >> /dev/null
  echo "b$I" > example-b.txt
  git commit -am "Commit $I, branch b" >> /dev/null
done


echo "\n\n"
echo "STATE OF BRANCH a"
echo "========================================================================="
git checkout branch-a
git log --oneline --decorate --color | cat


echo "\n\n"
echo "STATE OF BRANCH b"
echo "========================================================================="
git checkout branch-b
git log --oneline --decorate --color | cat

git checkout -q master

echo "\n"
echo "MERGING WITHOUT REBASING"
echo "========================================================================="

git merge --no-ff branch-a -m "Merging branch-a" >> /dev/null
git merge --no-ff branch-b -m "Merging branch-b" >> /dev/null

git log --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr)%Creset' --abbrev-commit | cat

echo "\n"
echo "MERGING AFTER REBASING"
echo "========================================================================="

git reset --hard HEAD~2 >> /dev/null

git checkout -q branch-a
git rebase master >> /dev/null
git checkout -q master
git merge --no-ff branch-a -m "Merging branch-a"  >> /dev/null

git checkout -q branch-b
git rebase master >> /dev/null
git checkout -q master
git merge --no-ff branch-b -m "Merging branch-b"  >> /dev/null

git log --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr)%Creset' --abbrev-commit | cat

echo "\n"
echo "FAST-FORWARD MERGING AFTER REBASING"
echo "========================================================================="

git reset --hard HEAD~2 >> /dev/null

git checkout -q branch-a
git rebase master >> /dev/null
git checkout -q master
git merge branch-a -m "Merging branch-a"  >> /dev/null

git checkout -q branch-b
git rebase master >> /dev/null
git checkout -q master
git merge branch-b -m "Merging branch-b"  >> /dev/null

git log --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr)%Creset' --abbrev-commit | cat

cd ..
rm -rf temp

Screen Shot 2014-12-04 at 21.06.15.png