Migrate from CVS to Git without losing history

I've not personally done a conversion from CVS to Git, but I believe Eric Raymond's cvs-fast-export is the tool to use. He has the man page posted here. cvsps is another tool maintained by Eric, but it has recently been deprecated in favor of cvs-fast-export. cvs2git is another tool which is built on some of the same machinery as cvs2svn. The latter was extremely adept, and so I have high hopes that cvs2git is equally good.

One thing to note: CVS is a pretty broken RCS. It's possible that it can have content that can't be reflected exactly in Git. In other words, there is some impedance mismatch there, but the tools try very hard to preserve as much as possible. Make sure to check your conversion and that you're happy with the results. You may need to fixup part of the Git history to get something more acceptable, but I doubt you'll need to.

Here is the process I used to migrate a SourceForge CVS repo to Git using cvs2git (latest stable release is here, but IIRC I used the github dev version), which works on both Windows and Linux without any compilation required since it's just Python.

Also, you don't need to own the repo with this method, you can for example migrate SourceForge projects that you don't own (you just need the right to checkout, so this works on any public repo).

How to import from sourceforge CVS to git.
First, you need to download/checkout the cvs repo with the whole history (not just checkout the HEAD/Trunk):

rsync -av rsync://PROJECT.cvs.sourceforge.net/cvsroot/PROJECT/\* cvs

then use cvs2git (python script, works on all platforms, no compilation needed):

python cvs2git --blobfile="blob.dat" --dumpfile="dump.dat" --username="username_to_access_repo" --options=cvs2git.options --fallback-encoding utf-8 cvs

this should have generated two files blob and dump containing your whole cvs history. You can open them in a text editor to check that the content seems correct.

then initialize your git repo inside another folder:

mkdir gitexport/
cd gitexport
git init

then load up the exported cvs history onto git:

cat ../{blob,dump}.dat | git fast-import

and then place the git commit cursor at the end of history:

git reset --hard

finally and optionally, you can push to your remote git repository:

git push -u origin master

of course you need before to git remote add origin https://your_repo_url

Note: cvs2git.options is a JSON formatted configuration file for cvs2git where you can specify transforms for various things like author names (so that their nicknames will be automagically transformed to their full name after import). See the documentation here or the included example options file.