There are various ways of using an Internet (or email) connection to stay up-to-date with any given area of the FreeBSD project sources, or all areas, depending on what interests you. The primary services we offer are Anonymous CVS, CVSup, and CTM.
While it is possible to update only parts of your source tree,
the only supported update procedure is to update the entire tree
and recompile both userland (i.e., all the programs that run in
user space, such as those in /bin
and
/sbin
) and kernel sources. Updating only part
of your source tree, only the kernel, or only userland will often
result in problems. These problems may range from compile errors
to kernel panics or data corruption.
Anonymous CVS and
CVSup use the pull
model of updating sources. In the case of
CVSup the user (or a
cron
script) invokes
the cvsup
program, and it interacts with a
cvsupd
server somewhere to bring your files
up-to-date. The updates you receive are up-to-the-minute and you
get them when, and only when, you want them. You can easily
restrict your updates to the specific files or directories that are
of interest to you. Updates are generated on the fly by the server,
according to what you have and what you want to have.
Anonymous CVS is quite a bit more
simplistic than CVSup in that it is just an extension to
CVS which allows it to pull changes
directly from a remote CVS repository.
CVSup can do this far more efficiently,
but Anonymous CVS is easier to
use.
CTM, on the other hand, does not interactively compare the sources you have with those on the master archive or otherwise pull them across. Instead, a script which identifies changes in files since its previous run is executed several times a day on the master CTM machine, any detected changes being compressed, stamped with a sequence-number and encoded for transmission over email (in printable ASCII only). Once received, these "CTM deltas" can then be handed to the ctm_rmail(1) utility which will automatically decode, verify and apply the changes to the user's copy of the sources. This process is far more efficient than CVSup, and places less strain on our server resources since it is a push rather than a pull model.
There are other trade-offs, of course. If you inadvertently wipe out portions of your archive, CVSup will detect and rebuild the damaged portions for you. CTM will not do this, and if you wipe some portion of your source tree out (and do not have it backed up) then you will have to start from scratch (from the most recent CVS "base delta") and rebuild it all with CTM or, with Anonymous CVS, simply delete the bad bits and resync.
All FreeBSD documents are available for download at https://download.freebsd.org/ftp/doc/
Questions that are not answered by the
documentation may be
sent to <freebsd-questions@FreeBSD.org>.
Send questions about this document to <freebsd-doc@FreeBSD.org>.