A redo file I've been using for my pet project

default.o.do

redo-ifchange env.sh && source env.sh

SRC=${1#"$BUILDDIR/"}

redo-ifchange "$SRC"  # <- Mark the source (.cpp) dependency to Redo's database

$COMPILE -c "$SRC" -o "$3" $CXXFLAGS $INCLUDES -MMD -MF "$1.o.dep"

DEPS=""
while read -r line; do    # Loop over all the header dependencies, and collect
  line=${line#*:}         # them as a list to $DEPS. There's no need (nor any
  DEPS=$DEPS${line#%\\}   # .do rule) to compile the headers, but redo-ifchange
done < "$1.o.dep"         # records the dependency relation to Redo's database.

echo "${DEPS#*:}" | xargs redo-ifchange  # Mark the header dependencies at once!

env.sh

BUILDDIR="build"

# list of directories prefixed like "-Idir1 -Idir2"
INCLUDES="-Iinclude"

COMPILE="c++-4.6"
CXXFLAGS="-std=c++0x"

LINK=$COMPILE