Something that I did create over some years – there is nothing similar that I have found as a open/OSS solution, so therefore I’d like to share it.

#!/bin/bash

if [ -f ~/tmp/git2svn.lock ]; then
 echo "git2svn is already processing..."
 exit 0
else
 touch ~/tmp/git2svn.lock
fi

echo "$(date --iso-8601=minutes) === git2svn.sh sync repos ==="

for repo in $HOME/repos/* ; do
 cd "${repo}"

 git checkout -b svn/git-svn
 git checkout svn/git-svn
 git svn fetch
 git svn rebase
 git checkout master
 git pull --rebase upstream master
 git checkout svn/git-svn
 MESSAGE=`git log --pretty=format:'%ai | %B [%an]' HEAD..master`
 git merge --no-ff --no-log -m "${MESSAGE}" master
 git svn dcommit
 git checkout master
 git merge svn/git-svn
 git push upstream master

done

rm ~/tmp/git2svn.lock

The trick is to use two different local only branches in which you do the merging vice versa. Just using one branch like master will cause serious issues.