minimal/do: add support for -x -v -d -c options.

-x, -v, and -d are the same as redo.

-c means "continuable", which disables the feature that deletes (and
forgets) all targets at the start of each run.  This is a little risky,
since minimal/do still doesn't understand dependencies, but it allows
you to run minimal/do several times in succession, so that

    minimal/do -c a
    minimal/do -c b
is the same as
    minimal/do a b

README.md

@@ -33,7 +33,7 @@ If you've ever thought about rewriting GNU make from scratch, the idea of
 doing it in 250 lines of shell script probably didn't occur to you.  redo is
 so simple that it's actually possible.  For testing, I actually wrote an
 even more minimal version, which always rebuilds everything instead of
-checking dependencies, in 150 lines of shell (about 3 kbytes).
+checking dependencies, in 210 lines of shell (about 4 kbytes).
 
 The design is simply that good.
 

minimal/do

@@ -36,30 +36,56 @@ export REDO=$(cd "${dir:-.}" && echo "$PWD/$base")
 if [ "$base" = "redo-ifchange" ]; then ifchange=1; else ifchange=; fi
 
 DO_TOP=
+if [ -z "$DO_BUILT" ]; then
+	export _do_opt_debug=
+	export _do_opt_exec=
+	export _do_opt_verbose=
+	export _do_opt_continuable=
+fi
+while getopts dxvc _opt; do
+	case $_opt in
+		d) _do_opt_debug=1 ;;
+		x) _do_opt_exec=x ;;
+		v) _do_opt_verbose=v ;;
+		c) _do_opt_continuable=1 ;;
+		*) printf "\nusage: $0 [-d] [-x] [-v] [-c] <targets...>\n" >&2
+		   exit 99
+		   ;;
+	esac
+done
+shift "$((OPTIND - 1))"
+_debug() {
+	[ -z "$_do_opt_debug" ] || echo "$@" >&2
+}
+
 if [ -z "$DO_BUILT" ]; then
 	DO_TOP=1
-	[ -n "$*" ] || set all  # only toplevel redo has a default target
+	[ "$#" -gt 0 ] || set all  # only toplevel redo has a default target
 	export DO_BUILT=$PWD/.do_built
 	: >>"$DO_BUILT"
+	sort -u "$DO_BUILT" >"$DO_BUILT.new"
+	if [ -z "$_do_opt_continuable" ]; then
 		echo "Removing previously built files..." >&2
-	sort -u "$DO_BUILT" | tee "$DO_BUILT.new" |
+		while read f; do printf "%s\0%s.did\0" "$f" "$f"; done <"$DO_BUILT.new" |
-	while read f; do printf "%s\0%s.did\0" "$f" "$f"; done |
 		xargs -0 rm -f 2>/dev/null
+	fi
 	mv "$DO_BUILT.new" "$DO_BUILT"
 	DO_PATH=$DO_BUILT.dir
 	export PATH=$DO_PATH:$PATH
 	rm -rf "$DO_PATH"
 	mkdir "$DO_PATH"
 	for d in redo redo-ifchange; do
-		ln -s "$REDO" "$DO_PATH/$d";
+		ln -s "$REDO" "$DO_PATH/$d"
 	done
 	[ -e /bin/true ] && TRUE=/bin/true || TRUE=/usr/bin/true
 	for d in redo-ifcreate redo-stamp redo-always; do 
-		ln -s $TRUE "$DO_PATH/$d";
+		ln -s $TRUE "$DO_PATH/$d"
 	done
 fi
 
 
+
+
 _find_dofile_pwd()
 {
 	dofile=default.$1.do
@@ -98,8 +124,10 @@ _run_dofile()
 	read line1 <"$PWD/$dofile" || true
 	cmd=${line1#"#!/"}
 	if [ "$cmd" != "$line1" ]; then
+		set -$_do_opt_verbose$_do_opt_exec
 		/$cmd "$PWD/$dofile" "$@" >"$tmp.tmp2"
 	else
+		set -$_do_opt_verbose$_do_opt_exec
 		:; . "$PWD/$dofile" >"$tmp.tmp2"
 	fi
 }
@@ -108,7 +136,9 @@ _run_dofile()
 _do()
 {
 	local dir="$1" target="$2" tmp="$3"
-	if [ -z "$ifchange" ] || ( [ ! -e "$target" -o -d "$target" ] && [ ! -e "$target.did" ] ); then
+	if [ -z "$ifchange" ] ||
+	    ( [ ! -e "$target" -o -d "$target" ] &&
+	      [ ! -e "$target.did" ] ); then
 		printf '%sdo  %s%s%s%s\n' \
 			"$green" "$DO_DEPTH" "$bold" "$dir$target" "$plain" >&2
 		echo "$PWD/$target" >>"$DO_BUILT"
@@ -135,7 +165,7 @@ _do()
 		mv "$tmp.tmp2" "$target" 2>/dev/null
 		rm -f "$tmp.tmp2"
 	else
-		echo "do  $DO_DEPTH$target exists." >&2
+		_debug "do  $DO_DEPTH$target exists." >&2
 	fi
 }
 
@@ -149,7 +179,7 @@ _dir_shovel()
 		_dirsplit "${xdir%/}"
 		xbasetmp=${base}__$xbase
 		xdir=$dir xbase=$base/$xbase
-		echo "xbasetmp='$xbasetmp'" >&2
+		_debug "xbasetmp='$xbasetmp'" >&2
 	done
 }
 
@@ -171,8 +201,10 @@ _redo "$@"
 [ "$?" = 0 ] || exit 1
 
 if [ -n "$DO_TOP" ]; then
+	if [ -z "$_do_opt_continuable" ]; then
 		echo "Removing stamp files..." >&2
 		[ ! -e "$DO_BUILT" ] ||
 		while read f; do printf "%s.did\0" "$f"; done <"$DO_BUILT" |
 		xargs -0 rm -f 2>/dev/null
+	fi
 fi