@@ -69,9 +69,10 @@
 m4=${m4:-$_m4}
 has nasm && asm=nasm
 has yasm && asm=yasm # prefer yasm
 export gen=${gen:-gen}
-library=${libkind:-static} # {static|shared|both}
+library=${library:-static} # {static|shared|both}
+export verbose=${verbose:-quiet} # {no|quiet|loud}
 
 doc=${doc:-yes}
 export doc_html=${doc_html:-yes}
 export doc_pdf=${doc_pdf:-yes}
@@ -134,22 +135,78 @@
 	macro_compile_env="$macro_compile_env -Datom_target_bits=$bits"
 fi
 
 
-comp_mac() { $m4 $macro_compile_env -I "$gen" $3 "$1" > "$2"; }
-comp_asm() { $asm "-f$bin_fmt" -i "$gen" $1 -o "$2"; }
+if test "$COLORTERM" != ""; then
+	announce() {
+		test "$verbose" = "silent" && return
+		color="$1" cmd="$2"; shift 2;
+		printf " → [38;5;$color;1m$cmd"
+		for a in "$@"; do
+			if test ${a:0:1} = "-"; then
+				printf " $a";
+			else
+				printf " $a";
+			fi
+		done
+		echo
+	}
+else
+	announce() { shift; echo " --> " $@; }
+fi
+
+# the following function is called to report a command invocation
+# the person compiling the library. the first argument should be
+# an ansi format string; this is used to color-code the tool being
+# launched and thus should be different for each one.
+report() { announce $@; shift; $@; }
+comp_mac() {
+	local src=$1
+	local output=$2
+	local flags=$3
+	if test -e "$output"; then
+		if test ! "$output" -ot "$src"; then
+			return
+		fi
+	fi
+	         $m4 $macro_compile_env -I "$gen" $flags "$src"  > "$output"
+	announce 207 $m4 $macro_compile_env -I "$gen" $flags "$src" \> "$output"
+	# yes, this is incredibly stupid. if you know a better way, feel
+	# free to submit a fix. the problem is there's no way to pass >
+	# to report in such a way that it'll do the right thing, and if
+	# you just write > it redirects *report's* output, instead of
+	# m4's. piece of shit that it is, m4 doesn't have any way to emit
+	# output into a fille - stdout only apparently. tl;dr i hate bash.
+}
+comp_asm() {
+	local src=$1
+	local output=$2
+	local flags=$3
+	if test -e "$output"; then
+		if test ! "$output" -ot "$src"; then
+			return
+		fi
+	fi
+	report 198 $asm $flags "-f$bin_fmt" -i "$gen" "$src" -o "$output";
+}
 comp_co()  { comp_c $1 $2 "-c -fPIC"; }
 comp_c(){
-	src=$1
-	output=$2
-	flags=$3
-	$cc $src $3 -std=c11 -isystem "$out" -isystem "$gen" -isystem "arch/" -nostdlib "-L$out" "-o$output"
+	local src=$1
+	local output=$2
+	local flags=$3
+	if test -e "$output"; then
+		if test ! "$output" -ot "$src"; then
+			return
+		fi
+	fi
+	# only rebuild the file if the source file is newer
+	report 213 $cc $src $3 -std=c11 -isystem "$out" -isystem "$gen" -isystem "arch/" -nostdlib "-L$out" "-o$output"
 }
 
 scan() { find "$1" -name "$2"; }
 
 say "commencing libk build $build at $(timestamp)"
-set -x
+# set -x
 
 # get type data
 mkdir -p $gen
 $cc -D_emit_m4_include arch/typesize.c -o $gen/typesize 
@@ -200,9 +257,9 @@
 	for mod in ${modules[@]}; do
 		for doc in $(scan $mod '*.md'); do
 			base="$(basename $doc)"
 			stem="${base%%.md}"
-			global/build-manpage.sh "$doc"
+			report 177 global/build-manpage.sh "$doc"
 		done
 	done
 fi
 
@@ -248,16 +305,16 @@
 # configured to be built
 
 if test $build_static_library == yes; then
 	for obj in ${fn_objects[@]} ${rt_objects[@]} ${data_objects[@]}; do
-		ar rc $out/libk.a $obj
+		report 120 ar rc $out/libk.a $obj
 	done
-	ranlib $out/libk.a
+	report 105 ranlib $out/libk.a
 fi
 
 if test $build_shared_library == yes; then
-	ld -r ${rt_objects[@]} -o $out/boot.o
-	ld -shared ${fn_objects[@]} -o $out/libk.so
+	report 216 ld -r ${rt_objects[@]} -o $out/boot.o
+	report 216 ld -shared ${fn_objects[@]} -o $out/libk.so
 fi
 
 # fifth pass: compile the executable tools
 # against the libraries created in pass 5