So, recently I found some projects from 10+ years back that I had a load of tarballs/zip files for which were taking up quite a bit of backup space. I figured I could unzip each of the repositories in date order and put the changes into a git repository in order to save a bit of space. Here are the commands to do this:

# Put the list of files to import in a file and manually
# edit the order if required to make the history the
# correct order
ls ../tarballs/*.bz2 > ../file_list
git init .
for i in `cat ../file_list`; do
 rm -fr *; # Clear out for next tarball
 tar xjf $i;
 git add -A; # Add any new files
 git add -u; # Remove any files removed from tarball
 git commit -am $i; # Commit with the filename
done

I also did this with some backups from an old psion – converting the 50 or so tarballs to a git repo reduced 500mb of backups to 30mb of git…