The Tcl and Tk source repositories can be found at
The version control system used for these is Fossil.
The remainder of this page follows Fossil's generic Quickstart Guide , modified to suit Tcl/Tk development.
Prebuilt binaries for the major platforms (Linux, OSX, Windows, BSD) are available at http://www.fossil-scm.org/download.html Building it yourself is of course possible as well.
Fossil works with repository files (a database with the project's complete history) and with checked-out local trees (the working directory you use to do your work). The workflow for Tcl and Tk looks like this:
First, clone the repository
fossil clone http://mirror1.tcl.tk/tcl tcl.fossil fossil pull http://core.tcl.tk/tcl -R tcl.fossil fossil clone http://mirror1.tcl.tk/tk tk.fossil fossil pull http://core.tcl.tk/tk -R tk.fossil
We are using mirror1 because the repositories are large and http://core.tcl.tk/ is bandwidth-limited. To prevent fossil from remembering the wrong url for pushing we then follow this by pulls from the proper repository. This will also import all changes pushed while we were cloning around.
Then create local checkouts to work with (using Tcl as example):
mkdir /somewhere/tcl cd /somewhere/tcl fossil open /wherever/you/have/tcl.fossil
Now you have the most recent revision of Tcl's trunk (ex-CVS HEAD) in the directory. Hacking can commence.
For those which have worked on the core before, using CVS, please see the Fossil vs CVS Commands.