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dotstuff
David Reiss <davidn@gmail.com>
2012-04-24


INTRO:

dotstuff is a dotfile management system. It was designed for maintaining
similar but slightly different sets of dotfiles and scripts on different
systems. Not all configuration languages support conditional expressions
or substitution, so it includes a simple preprocessor that lets you
easily tweak dotfiles for the local environment, while keeping one copy
of the common parts. All dotfiles are kept in a single version-
controlled directory, that you can manage however you like (the default
uses mercurial).


TO START:

1) In your home directory, run:
   hg clone https://bitbucket.org/davidn/dotstuff
2) Then run:
   ~/dotstuff/DOT/dot -g
   This will put a symlink to this script in ~/.bin
3) Modify your $PATH to include $HOME/.bin so that you can run it as
   just 'dot'.
4) If you don't like mercurial, rm -rf ~/dotstuff/.hg and set it up your
   favorite vcs.
5) Put some dotfiles in ~/dotstuff.
6) Run 'dot' to see what changes will happen, and 'dot -g' to make them.


NEW SYSTEM SETUP:

1) Clone your dotstuff repo to ~/dotstuff on the new system.
2) Optionally, run: ~/dotstuff/DOT/dot --set-env bar
3) Run: ~/dotstuff/DOT/dot
   to see what will change.
4) Tweak files in ~/dotstuff as necessary to avoid breakage and preserve
   local changes, then run: ~/dotstuff/DOT/dot -g
   to copy files. You can add '-b' to keep backups of all replaced
   files.
5) You may also want to log out and in again to check that everything is
   working, especially if you changed ~/.xsession or similar.


USAGE:

The ~/dotstuff directory contains copies of all the dotfiles you want to
manage. When you run 'dot' by itself, it will show you a diff between
what's in ~/dotstuff and what's in ~. To actually perform the copies,
run 'dot -g'. (Look at main() for more options.)

The initial dot will be added implicitly, that is, your bashrc goes in
~/dotstuff/bashrc (not ~/dotstuff/.bashrc).

Subdirectories are fine: ~/dotstuff/ssh/config,
~/dotstuff/vim/plugin/foo.vim, etc.

The preprocessor syntax is described below.

Running 'dot' with any non-flag arguments will pass through the command
line to your favorite vcs, with the current directory set to ~/dotstuff.
This makes it easy to tweak files and commit changes without cd'ing all
over the place. A typical pattern looks like:

  some/dir$ vi ~/dotstuff/bashrc
  some/dir$ dot  # to check the changes
  some/dir$ dot -g
  some/dir$ exec bash  # to pick up changes
  some/dir$ dot ci -m 'bashrc: ...'
  some/dir$ dot push

The special file '~/dotstuff/crontab' will get installed as the local
crontab. You probably want to limit this to certain environments using
the preprocessor.

Directories with all-uppercase names are ignored. So ~/dotstuff/DOT/dot
doesn't get copied anywhere (~/.bin/dot gets symlinked to it).
Similarly, dotstuff/ENV/ files aren't copied anywhere, but they are
synced so that there's one view of them.

This means you can create ~/dotstuff/NOTES/blah for small text files and
things that you want to get synced between machines, but not copied to
your home directory.

(Why not put this script directly in ~/dotstuff/bin/dot? That makes it
hard to edit, because you'd need to keep running 'dot -g' to test
changes while it may not be a runnable state. Why not put this script in
a different repo than the dotfiles themselves? So that you only
have to clone one thing for a new system setup.)


ENVIRONMENTS:

If you have accounts on multiple systems, give them each a name (sets of
identical systems can get the same name). Then use preprocessor
directives to turn on and off parts of files depending on the system. Or
handle external paths that aren't in the same place.

Environments are files in ~/dotstuff/ENV/. To use one, create a symlink
~/.dotstuffenv that points to one. The command 'dot --set-env foo' does
this for you.

Environment files are simply a list of key=value lines, or just keys
(which get the value '1'). The basename of the file is also added as a
key with the value '1', as is the key 'true'. The key 'env' is set to
the basename of the environment file.


PREPROCESSOR:

The preprocessor is line-based. All directive lines start with '---@'.

---@link target
Replace this file by a symlink to target. You can also use actual
symlinks if your vcs supports versioning symlinks, but ---@link is more
flexible because it supports macro expansion and expands '~/'.

---@if [expr]
---@else [expr]
---@unless [expr]
---@
Conditionally include the lines in between the directives.
Note that these do not nest! Each ---@if just evaluates the expression
and turns copying on or off, ---@unless uses the negation of the
expression, and ---@else negates the previous directive.

---@@ comment
Comments just get removed.

---@ignore
Stop processing immediately and don't touch the corresponding dotfile.

---@vis {public|private}
Make the corresponding file public (world-readable) or private. Useful
on multi-user systems if you want to share some dotfiles but not others.
All files are private by default.

---@emptyok
Allow creating an empty (or just whitespace) dotfile. (If a file turns
out empty without ---@emptyok, it gets deleted.)

---@-asdf-@---
Anywhere in any line, gets replaced by the defintion of asdf in this
environment. If it's not defined, that's a runtime error.


If a file looks like binary (there's a nul byte in first 1K), no
substitutions are done.

If a file ends up with no non-whitespace characters, it gets deleted
(unless ---@emptyok was found).


Expressions (for ---@if, etc.) are the following:

  key
    true if key is defined (to any value)
  key|key|key
    true if any of those keys are defined
  key=value
    true if key is defined and has that value
  key=value|value|value
    true if key is defined and has any of those values



TODO:

handle changes to root-owned files outside of HOME?
add syntax-check-only mode
make directives more powerful? (nesting, elif, proper else)
delete stuff in dstfn that shouldn't be there, if depth # > 0?