git-svn-demo.sh

# http://git-scm.com/book/en/Git-and-Other-Systems-Git-and-Subversion
# sudo apt-get install subversion git-svn
set -euv


function create_local_svn_copy {
	local svn_dir=$1
	local svn_url=$2
	#
	pre_revprop_change_file=$svn_dir/hooks/pre-revprop-change

	# set up locally
	mkdir $svn_dir
	svnadmin create $svn_dir
	#
	cat -- > $pre_revprop_change_file <<EOF
#!/bin/sh
exit 0;
EOF
	chmod +x $pre_revprop_change_file

	# clone down the repo
	svnsync init file://$svn_dir $svn_url
	svnsync sync file://$svn_dir > svnsync_sync.out
}

function inspect_git_dir {
	local git_dir=$1

	cd $git_dir
	git branch -a
	git log --pretty=oneline -n 5 | head
}

function make_branch_and_commit {
	local git_dir=$1
	local branchname=$2

	# create a new branch
	cd $git_dir
	git checkout -b $branchname

	# make some modifications
	filename=README.txt
	regex='s/make/break/g'
	perl -pi.bak -e $regex $filename
	git commit $filename -m "do $regex"
	filename=python/google/protobuf/message.py
	regex='s/object/slobject/g' 
	perl -pi.bak -e $regex $filename
	git commit $filename -m "do $regex"
}

function update_git_master {
	local git_dir=$1

	cd $git_dir
	git checkout master && \
		git svn rebase
}

function merge_branch_and_push {
	local git_dir=$1
	local branchname=$2

	update_git_master $git_dir
	cd $git_dir
	git checkout master && \
		git merge --no-ff $branchname -m "merge $branchname" && \
		git svn dcommit
}

function checkout_svn_and_inspect {
	local svn_dir=$1
	temp_dir=$(mktemp -d)

	echo "checking out svn to $temp_dir"
	# verify that was merge in a single commit
	svn co file://$svn_dir $temp_dir >/dev/null && \
		cd $temp_dir && \
		svn log -l 2 -v
}


svn_dir=~/test-svn-repo
git_dir=~/test-git-repo
svn_url=http://progit-example.googlecode.com/svn/
branchname=mybranch

if [ ! -d ${svn_dir}.orig ]; then
	create_local_svn_copy $svn_dir $svn_url
	cp -R ${svn_dir} ${svn_dir}.orig
else
	# don't pull from network if you don't have to
	cp -R ${svn_dir}.orig ${svn_dir}
fi

# look at svn repo before changes
checkout_svn_and_inspect $svn_dir

# this gets you a git version of svn at $git_dir
git svn clone file://$svn_dir -s $git_dir >git_svn_clone.out 2>git_svn_clone.err

# inspect what the git repo looks like
inspect_git_dir $git_dir

make_branch_and_commit $git_dir $branchname

merge_branch_and_push $git_dir $branchname

# look at svn repo after changes
checkout_svn_and_inspect $svn_dir