diff -uNr a/vtools/Makefile b/vtools/Makefile
--- a/vtools/Makefile 85500ed7a489bcd8d604fd29696a630d9b43a7422bb23f393c77c5029f34a729316a0a19e5bd4ec591e06f4b9fb170e119739e3d6ac8f20bf11c613c5c7c116b
+++ b/vtools/Makefile 67cefb8f1983138b975a6ec3402c6718e3fa8855201d2c41f4f4cd68284a21fc853cc56ce1d03b61a1d93df3ddcde48979b1a7ede00d077e31f39bd647daf1ed
@@ -5,6 +5,10 @@
 vpatch:
 	gprbuild -Pvpatch.gpr
 
+vflow:
+	gprbuild -Pvflow.gpr
+
 clean:
 	gprclean -Pvdiff.gpr
 	gprclean -Pvpatch.gpr
+	gprclean -Pvflow.gpr
diff -uNr a/vtools/manifest b/vtools/manifest
--- a/vtools/manifest 35a57f6c4eaad4c3084874e6f97aceba39d8b54879b41a1498988fc45015bc618e72400887accc694e164f9704ecb33a8db29c6d135ea9880ec1345402eafda9
+++ b/vtools/manifest 47bb2feba0952de6c08f9f9c644500bf867571c2c5058c70475811c6de72fa3f8297ca90155e12da32901569d9da2d8e4d084635e72cc85c0902f1aaf7753929
@@ -16,3 +16,4 @@
 617378 bvt vtools_vsh_utils_one_binary Merge all v.sh Ada utilities into one.
 617638 bvt vtools_vsh_ada_vfilter Add an implementation of vfilter in Ada.
 619714 bvt vtools_vsh_shellcheck A round of shellcheck on the v.sh source.
+620790 bvt vtools_ascii_visualization Add "vtree" command, work towards pipeable output.
diff -uNr a/vtools/src/vflow.adb b/vtools/src/vflow.adb
--- a/vtools/src/vflow.adb 400069490b8212c36d75f27a9935f5017ad6bdb49c9f520293082a4dcc4a1e902fe3733cf34c4356c8a0c315905b8534236ad9b1557a32ec501742693f644514
+++ b/vtools/src/vflow.adb e6faf838d6886b05028f7483b7ff738584217d570a2a894fbe91380614a576f25952120f7fa5c1dff3bd6b16e53364cb5859ed2407412ab121c1c76d0826044c
@@ -366,6 +366,8 @@
 	 for I in Vpatch_Order'Range loop
 	    if Selected_Vpatches(Vpatch_Order(I)) then
 	       Put_Line("P " & Integer'Image(Vpatch_Order(I)));
+	    else
+	       Put_Line("p " & Integer'Image(Vpatch_Order(I)));
 	    end if;
 	 end loop;
       end Print_Flow_Or_Conflicts;
diff -uNr a/vtools/v.sh b/vtools/v.sh
--- a/vtools/v.sh 535fd4d5c7268d52140490ddb24d4ada36a3269b5d285c98da2db542b6c0fe52a844e6c273fcb1ee9d6c45c04e2fdb82e48285e4e970485da5daa86c6c578e8e
+++ b/vtools/v.sh ba8feba74997e15453711dd8c414240605d87674dabd3feac0fdba6a97cb2beefbf0ef03b28b02d4b1d9ae251c58c9400b02f6359c1a3d76ad351e31c6f4caae
@@ -2,6 +2,8 @@
 
 set -e
 
+allkeyword="all"
+
 vgpgdir=""
 vpatches=""
 filtered=""
@@ -18,13 +20,14 @@
 v descendants patch       -- list patch descendants
 v origin hash             -- find patch that introduced the hash
 v press directory leaves  -- press all patches up to head
+v vtree leaves            -- print the vtree structure for a press
 EOF
 	exit 0
 }
 
 checkdir() {
 	if [ ! -d "$1" ]; then
-		echo "$1 directory not found"
+		>&2 echo "$1 directory not found"
 		kill -TERM 0
 	fi
 }
@@ -47,13 +50,20 @@
 	if [ ! -z "$vgpgdir" ]; then
 		rm -rf "$vgpgdir"
 	fi
-	exit 0
+	exit "$1"
+}
+exit_success() {
+	cleanup 0
 }
-trap cleanup TERM INT
+
+fail() {
+	cleanup 1
+}
+trap fail TERM INT
 
 exit_msg() {
-	echo "$1"
-	cleanup
+	>&2 echo "$1"
+	cleanup 1
 }
 
 verify() {
@@ -105,7 +115,8 @@
 
 vpatchnos() {
 	awk -v VF="$vpatches" '
-FILENAME==VF {a[$1]=$2} FILENAME=="-" {print a[$1]}' "$vpatches" -
+FILENAME==VF {a[$1]=$2}
+FILENAME=="-" {if (!($1 in a)) {print "not found:",$1} else {print a[$1]}}' "$vpatches" -
 }
 
 vpatchnames() {
@@ -114,12 +125,15 @@
 }
 
 vpatchflow() {
-	[ -z "$*" ] && exit_msg "No leaves selected."
 	filterall | internall >"$filtered"
-	if [ "$*" = "-" ]; then
+	if [ "$*" = "$allkeyword" ] || [ -z "$*" ]; then
 		echo "S" >"$selfile"
 	else
-		echo $* | tr ' ' '\n' | vpatchnos | sed -e 's/^/s /g' - >"$selfile"
+		echo $* | tr ' ' '\n' | vpatchnos >"$selfile"
+		if >&2 grep "not found:" "$selfile"; then
+			fail
+		fi
+		sed -i -e 's/^/s /g' "$selfile"
 	fi
 	cat "$filtered" "$selfile" | \
 		vflow $(wc -l <"$filtered") $(wc -l <"$vpatches") >"$topo"
@@ -133,17 +147,17 @@
 END {if (err != 0) exit err; if (ok != 1) exit 3; exit 0;}' <"$topo"
     exitcode="$?"
     if [ "$exitcode" -eq "1" ]; then
-	    printf "\nConflicting leaves selected:\n"
-	    awk '$1 == "C" {print $2}' < "$topo" | vpatchnames | sort | uniq
-	    cleanup
+	    >&2 printf "\nConflicting leaves selected:\n"
+	    >&2 awk '$1 == "C" {print $2}' < "$topo" | vpatchnames | sort | uniq
+	    fail
     elif [ "$exitcode" -eq "2" ]; then
-	    printf "\nConflicting leaves selected:\n"
-	    awk '{print $2}' < "$topo" | vpatchnames
-	    cleanup
+	    >&2 printf "\nConflicting leaves selected:\n"
+	    >&2 awk '{print $2}' < "$topo" | vpatchnames
+	    fail
     elif [ "$exitcode" -eq "3" ]; then
-	    echo "Unknown error. Investigate in $vgpgdir:"
-	    cat "$topo"
-	    exit 0 # no cleanup
+	    >&2 echo "Unknown error. Investigate in $vgpgdir:"
+	    >&2 cat "$topo"
+	    exit 1 # no cleanup
     fi
 }
 
@@ -153,14 +167,14 @@
 
 if [ "$1" = "wot" ]; then
 	gpg --homedir "$vgpgdir" --logger-fd 1 --batch --keyid-format=long -k
-	cleanup
+	exit_success
 fi
 
 verifyall
 
 if [ "$1" = "patches" ]; then
 	cat "$vgpgdir"/signers.txt
-	cleanup
+	exit_success
 fi
 
 if [ "$1" = "graph" ]; then
@@ -170,7 +184,7 @@
 	svgfile="$1"
 	shift
 
-	vpatchflow -
+	vpatchflow
 	cat >"$dotfile" <<EOF
 digraph {
 node [shape=rectangle, color=black, style=bold]
@@ -182,7 +196,7 @@
 	echo "}" >> "$dotfile"
 	dot -Tsvg "$dotfile" -o "$svgfile"
 	# dot -Tcmapx $dotfile -o $svgfile.html-map
-	cleanup
+	exit_success
 fi
 
 if [ "$1" = "antecedents" ]; then
@@ -190,13 +204,14 @@
 	vpatch="$1"
 	shift
 
-	vpatchflow -
+	vpatchflow
 	vno=$(awk -v V="$vpatch" '$1==V {print $2}' < "$vpatches")
+	[ -z "$vno" ] && exit_msg "not found: $vpatch"
 	awk -v N="$vno" '
 ($1 == "I" || $1 == "d" ) && $2 == N {a[$3]=1}
 ($1 == "P") {if ($2 in a) {print $2}}
 ' "$topo" | vpatchnames
-	cleanup
+	exit_success
 fi
 
 if [ "$1" = "descendants" ]; then
@@ -204,13 +219,14 @@
 	vpatch="$1"
 	shift
 
-	vpatchflow -
+	vpatchflow
 	vno=$(awk -v V="$vpatch" '$1==V {print $2}' < "$vpatches")
+	[ -z "$vno" ] && exit_msg "not found: $vpatch"
 	awk -v N="$vno" '
 ($1 == "I" || $1 == "d" ) && $3 == N {a[$2]=1}
 ($1 == "P") {if ($2 in a) {print $2}}
 ' "$topo" | vpatchnames
-	cleanup
+	exit_success
 fi
 
 if [ "$1" = "origin" ]; then
@@ -220,24 +236,24 @@
 
 	filterall >"$filtered"
 	awk -v hash="$hash" '$5 == hash {print $1}' <"$filtered" | vpatchnames
-	cleanup
+	exit_success
 fi;
 
 if [ "$1" = "flow" ]; then
 	shift
 
 	vpatchflow $*
+	vpatchflowerr
 
-	echo "Press order:"
 	awk '$1 == "P" {print $2}' < "$topo" | vpatchnames
 
-	vpatchflowerr
-	cleanup
+	exit_success
 fi
 
 if [ "$1" = "press" ]; then
 	shift
 	dir="$1"
+	[ -z "$dir" ] && exit_msg "Provide press directory"
 	shift
 
 	[ -d "$dir" ] && exit_msg "Directory $dir already exists"
@@ -249,12 +265,28 @@
 	awk '$1 == "P" {print $2}' < "$topo" | vpatchnames | while read i; do
 		i=$(readlink -f "$i")
 		cd "$dir"
-		vpatch <"$i" >/dev/null
+		vpatch <"$i"
 		cd - >/dev/null
 	done
-	cleanup
+	exit_success
+fi
+
+if [ "$1" = "vtree" ]; then
+	shift
+
+	vpatchflow "$@"
+	awk -v VF="$vpatches" '
+function repeat(s,n) {i=0; while (i++ < n) {printf("%s",s);}}
+FILENAME==VF {n[$2]=$1} 
+FILENAME=="-" && ($1 == "I" || $1 == "d" ) {a[$2]++;b[$3]=1;}
+FILENAME=="-" && ($1 == "P" || $1 == "p") {
+   if (!($2 in a)) {a[$2]=0};
+   repeat(" ", a[$2]);
+   printf("%s%s%s\n",n[$2], ($2 in b) ? "" : " (*)", ($1 == "P") ? " +" : "" );
+}' "$vpatches" - <"$topo"
+	exit_success
 fi
 
-echo "Unknown command: $1"
 
-cleanup
+>&2 echo "Unknown command: $1"
+fail