The most recent released version of groff is always available by anonymous ftp.

The current development version of groff is available from a CVS repository. You can access it by first selecting a parent directory in which to create a working copy (call it, say, ~/cvswork), and then executing the commands

cd ~/cvswork
cvs -d:pserver:anonymous@cvs.savannah.gnu.org/sources/groff -z5 co groff

This creates a subdirectory, ~/cvswork/groff, with a ‘checked out’ copy of the CVS repository. An update of this working copy may be achieved, at any later time by invoking the commands

cd ~/cvswork/groff
cvs -z5 update -dP

Please read the CVS info pages for further details.

Finally, it is possible to access the CVS with a web browser.

Alternatively, you can download snapshots (which are updated twice a day). The complete groff source as a single file is available here.

A diff file relative to groff-⟨version⟩, the latest official groff release, is available at

http://groff.ffii.org/groff/devel/groff-⟨version⟩-current.diff.gz

Assuming that groff-⟨version⟩.tar.gz and groff-⟨version⟩-current.diff.gz are in the same directory, do the following to apply the diff file:

tar xzvf groff-⟨version⟩.tar.gz
cd groff-⟨version⟩
gunzip -c ../groff-⟨version⟩-current.diff.gz | patch -p1