Substitution

echo ${food:-Cake}  #=> $food or "Cake"

STR="/path/to/foo.cpp"
echo ${STR%.cpp}    # /path/to/foo
echo ${STR%.cpp}.o  # /path/to/foo.o
echo ${STR%/\*}      # /path/to
echo ${STR##\*.}     # cpp (extension)
echo ${STR##\*/}     # foo.cpp (basepath)
echo ${STR#\*/}      # path/to/foo.cpp
echo ${STR##\*/}     # foo.cpp
echo ${STR/foo/bar} # /path/to/bar.cpp