Use git merge driver to always resolve conflicts in file VERSION in favor of merge target

#mergedriver

Use git merge driver to always resolve conflicts in file VERSION in favor of merge target

.gitattributes

VERSION merge=always-ours

.gitconfig

[merge "always-ours"]
	name = Merge Ours
	driver = true

mergedriver_demo

#!/bin/bash -x

# Demonstrate how to use a merge driver to ensure that a single file VERSION always gets
# resolved as --ours in a merge conflict

echo "REPO SETUP"
# start clean
rm -Rf .git .gitbackup
git init
echo "CHECK OUT THIS .gitconfig"
cat .gitconfig
echo "CHECK OUT THIS .gitattributes"
cat .gitattributes
echo "CHECK OUT HOW .git/config LOOKS AFTER DOING include.path ../.gitconfig"
echo "(it's ../ because it's relative to .git sub-dir)"
git config --local include.path ../.gitconfig
cat .git/config
echo "first" >| README
echo "first" >| VERSION
git add .gitconfig .gitattributes README VERSION
git commit -m "first commit"
echo "CHECK OUT BRANCH AND CHANGE STUFF"
git checkout -b featurebranch
echo "branch" >| README
echo "branch" >| VERSION
git commit -am "branch commit"
echo "CHECK OUT MASTER AND MAKE CONFLICTING CHANGES"
git checkout master
echo "master" >| README
echo "master" >| VERSION
git commit -am "conflicting master commit"
# now there's two ways things could go so let's back up the .git folder
cp -r .git .gitbackup
# if we merge from master, we want to nuke the featurebranch change to VERSION
echo "MERGE FEATUREBRANCH ON TO MASTER"
echo "EXPECTED OUTPUT:"
cat VERSION
git merge featurebranch
cat VERSION
# now test in the other direction
echo "MERGE FEATUREBRANCH ON TO MASTER"
git reset --hard HEAD
mv -f .gitbackup .git
git checkout featurebranch
echo "EXPECTED OUTPUT:"
cat VERSION
git merge master
cat VERSION

output.log

+ echo 'REPO SETUP'
REPO SETUP
+ rm -Rf .git .gitbackup
+ git init
Initialized empty Git repository in /Users/jc01/nesta/mergedriver_demo/.git/
+ echo 'CHECK OUT THIS .gitconfig'
CHECK OUT THIS .gitconfig
+ cat .gitconfig
[merge "always-ours"]
	name = Merge Ours
	driver = true
+ echo 'CHECK OUT THIS .gitattributes'
CHECK OUT THIS .gitattributes
+ cat .gitattributes
VERSION merge=always-ours
+ echo 'CHECK OUT HOW .git/config LOOKS AFTER DOING include.path ../.gitconfig'
CHECK OUT HOW .git/config LOOKS AFTER DOING include.path ../.gitconfig
+ echo '(it'\''s ../ because it'\''s relative to .git sub-dir)'
(it's ../ because it's relative to .git sub-dir)
+ git config --local include.path ../.gitconfig
+ cat .git/config
[core]
	repositoryformatversion = 0
	filemode = true
	bare = false
	logallrefupdates = true
	ignorecase = true
	precomposeunicode = true
[include]
	path = ../.gitconfig
+ echo first
+ echo first
+ git add .gitconfig .gitattributes README VERSION
+ git commit -m 'first commit'
[master (root-commit) f052012] first commit
 4 files changed, 6 insertions(+)
 create mode 100644 .gitattributes
 create mode 100644 .gitconfig
 create mode 100644 README
 create mode 100644 VERSION
+ echo 'CHECK OUT BRANCH AND CHANGE STUFF'
CHECK OUT BRANCH AND CHANGE STUFF
+ git checkout -b featurebranch
Switched to a new branch 'featurebranch'
+ echo branch
+ echo branch
+ git commit -am 'branch commit'
[featurebranch ae20e61] branch commit
 2 files changed, 2 insertions(+), 2 deletions(-)
+ echo 'CHECK OUT MASTER AND MAKE CONFLICTING CHANGES'
CHECK OUT MASTER AND MAKE CONFLICTING CHANGES
+ git checkout master
Switched to branch 'master'
+ echo master
+ echo master
+ git commit -am 'conflicting master commit'
[master ce3aeb0] conflicting master commit
 2 files changed, 2 insertions(+), 2 deletions(-)
+ cp -r .git .gitbackup
+ echo 'MERGE FEATUREBRANCH ON TO MASTER'
MERGE FEATUREBRANCH ON TO MASTER
+ echo 'EXPECTED OUTPUT:'
EXPECTED OUTPUT:
+ cat VERSION
master
+ git merge featurebranch
Auto-merging VERSION
Auto-merging README
CONFLICT (content): Merge conflict in README
Automatic merge failed; fix conflicts and then commit the result.
+ cat VERSION
master
+ echo 'MERGE FEATUREBRANCH ON TO MASTER'
MERGE FEATUREBRANCH ON TO MASTER
+ git reset --hard HEAD
HEAD is now at ce3aeb0 conflicting master commit
+ mv -f .gitbackup .git
+ git checkout featurebranch
Switched to branch 'featurebranch'
+ echo 'EXPECTED OUTPUT:'
EXPECTED OUTPUT:
+ cat VERSION
branch
+ git merge master
Auto-merging VERSION
Auto-merging README
CONFLICT (content): Merge conflict in README
Automatic merge failed; fix conflicts and then commit the result.
+ cat VERSION
branch