Question

I have been following the tutorial http://www.burlingtontelecom.net/~ashawley/rcs/tutorial.html on how to work with files using RCS. This works well but only with one file. Is there a way to create an RCS file with directories as well?

I have a project folder called myproject, and in this directory I have all my files for that project. I want to create a revision control system for the myproject folder and all its files that are inside.

Answer 1

As William’s comment says, RCS only works with single files. (It also doesn’t seem to be particularly suitable for multiple-user stuff.)

Of course, nothing stops you from putting each (source) file in a directory under RCS control; in fact, this is essentially what CVS does (though in recent versions it handles the RCS data itself, rather than invoking RCS to do it as it used to do). Unfortunately, this fragments the change history rather badly; a commit affecting many files ends up as separate commits to each file, which just happen to have the same commit message (and timestamp?), and in general every file will have a different revision in what the user might like to think of as the “same” revision. (This makes tags quite essential.) CVS also has issues with the atomicity of commits: you could end up with commit A and commit B getting tangled up, such that in file foo commit A precedes commit B, but in file bar commit B precedes commit A!

SVN (Subversion) is an attempt to rectify some of the problems in CVS, though it also brings some new limitations, and keeps many of the existing ones; it is probably wiser (as William implies) to just use a distributed version control system (DVCS) for your multi-file projects. There are many choices:

• Darcs uses a unique patch-based model: a repository is treated as a sequence of patches, which can be applied to an empty tree to build the current revision; patches can often be reordered by “commuting” pairs of patches, and cherry-picking patches from other repositories is quite easy. The downside is that the change history is a bit less clear than in most DVCSes. See http://wiki.darcs.net/Using/Model, http://en.wikibooks.org/wiki/Understanding_Darcs/Patch_theory.
• Directed-acyclic-graph (DAG) based DVCSes model a repository as a directed acyclic graph of revisions, where each revision can have one parent, two parents, or perhaps more. Each revision has an associated file tree state; sometimes renames are also tracked somehow.
  • Git, as already mentioned. Has a very simple model, but a very complicated interface: there are many commands, some of which are not really intended for humans to use (owing to many parts of it having been prototyped in shell script, probably), so it can be hard to find the ones you want. Also, its model might be a bit too simple: it doesn’t track renames at all.
  • Bazaar (a.k.a. bzr) has a more complicated model, including support for file/directory renames. It’s difficult to say how much more complicated, though, because whatever documentation may exist is not nearly as accessible as Git’s. It does, however, have a rather simpler user interface, and there are a number of useful plugins, including a distributed-development-friendly SVN plugin: committing from a branch back to SVN need not interfere with the validity of others’ branches of your branches, and bzr metadata is even committed back to SVN. Can make things much less painful if you want to start hacking on an SVN-based project without having commit access, but hope to get your changes committed eventually. Bazaar is my personal favorite DAG-based DVCS.
  • Mercurial (a.k.a. hg) seems fairly similar to Bazaar, though I think it tracks renames only for individual files, not for directories. It also supports plugins, though its SVN plugin isn’t as nice as Bazaar’s: it doesn’t support lossless commits, so branching from other peoples’ branches is unwise. I don’t have much experience with it, so I can’t really evaluate it in-depth.