last.sh will exit 1 when no file found; handle it in next.sh. meaning um next works in empty dirs

shell/last.sh

@@ -1,3 +1,5 @@
+#!/bin/bash
+
 # Get the last file name of any numbered series of text files.
 
 # file format:
@@ -6,6 +8,14 @@
 # in plain terms:
 #   [leading numbers with consistent width].[optional string descriptor and . separator][md|txt]
 
-# TODO: signal no file found, so that next knows to create one.
-# Grep exits 1, but tail exits 0.
-ls | egrep '^[[:digit:]].*\.md|txt' | tail -n 1
+UMALLFILES=`ls | egrep '^[[:digit:]].*\.(md|txt)'`
+LASTSTATUS=$?
+
+# NOTE: if we don't stop and signal here, tail will exit 0
+if [ "$LASTSTATUS" -ne 0 ]; then
+    echo "no files found" >&2
+    exit 1
+fi
+
+# NOTE: if var isn't quoted echo will change newlines to spaces
+echo "$UMALLFILES" | tail -n 1