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+# redo-c
+
+redo-c is an implementation of the redo build system (designed by
+Daniel J. Bernstein) in portable C with zero external dependencies.
+
+## Documentation
+
+Please refer to the documentation for
+[redo in Python])(https://github.com/apenwarr/redo/blob/master/README.md),
+or the [tutorial by Jonathan de Boyne Pollard](http://jdebp.eu/FGA/introduction-to-redo.html)
+for usage instructions.
+
+## Notes about the redo-c implementation of redo
+
+* Without arguments, `redo` behaves like `redo all`.
+
+* `.do` files always are executed in their directory, arguments are
+  relative paths.
+
+* Standard output of `.do` files is only captured as build product if
+  `redo -s` is used, or the environment variable `REDO_STDOUT` is set to 1.
+  Else, standard output is simply displayed.
+
+* Non-executable `.do` files are run with `/bin/sh -e`.
+  `redo -x` can be utilized to use `/bin/sh -e -x` instead, for
+  debugging `.do` files or verbose builds.
+
+* Executable `.do` files are simply executed, and should have a shebang line.
+
+* When a target makes no output, no target file is created.  The target
+  is considered always out of date.
+
+* `default.do` files are checked in all parent directories up to `/`.
+
+* Parallel builds can be started with `redo -j N` (or `JOBS=N redo`),
+  this uses a job broker similar to but not compatible with GNU make.
+
+* To detect whether a file has changed, we first compare `ctime` and
+  in case it differs, a SHA2 hash of the contents.
+
+* Dependencies are tracked in `.dep.BASENAME` files all over the tree.
+  This is an implementation detail.
+
+* Builds can be started from every directory and should yield same results.
+
+* `redo -f` will consider all targets outdated and force a rebuild.
+
+* `redo -k` will keep going if a target failed to build.
+
+## Copying
+
+To the extent possible under law, Leah Neukirchen <leah@vuxu.org>
+has waived all copyright and related or neighboring rights to this work.
+
+http://creativecommons.org/publicdomain/zero/1.0/