function sos {
srcdir=`echo $PWD|sed "$SRC_REPLACEMENT"`
objdir=`echo $PWD|sed "$OBJ_REPLACEMENT"`
if test $srcdir != $PWD; then
        cd $srcdir
elif test $objdir != $PWD; then
        if test -d $objdir; then
                cd $objdir
        else
                echo "create $objdir"
                mkdir -p $objdir
                cd $objdir
        fi
fi
}