diff --git a/bin/makebook b/bin/makebook
index 2378f27..e8e053b 100755
--- a/bin/makebook
+++ b/bin/makebook
@@ -6,10 +6,10 @@
 #
 #**********************************************************#
 #                       makebook                           #
-#  	     written by Donald P. Goodman III	 	           #
-#		   Copyright (C) 2011			                   #
-#							                               #
-#	       Impose pdf pages for binding		               #
+#  	     written by Donald P. Goodman III	 	   #
+#		   Copyright (C) 2011			   #
+#							   #
+#	       Impose pdf pages for binding		   #
 #**********************************************************#
 #
 # This program is free software:  you can redistribute it
@@ -30,9 +30,11 @@
 #**********************************************************#
 #                     begin the code                       #
 #**********************************************************#
+# make script more portable and secure
+PATH=/bin:/usr/bin:/usr/local/bin ; export PATH
 umask 033
 # define our revision number variable for rcs
-REVISION="2.0"
+REVISION="2.1"
 # define error codes
 E_WRONG_ARGS=64		# too many or few args
 E_BAD_SIG_TYPE=65	# invalid type of signature
@@ -74,6 +76,14 @@ command -v pdftk >/dev/null 2>&1 ||
 	{ echo >&2 "makebook:  error:  requires pdftk, but it's not installed";
 	exit $E_NO_PROG;
 	}
+command -v dc >/dev/null 2>&1 ||
+	{ echo >&2 "makebook:  error:  requires dc, but it's not installed";
+	exit $E_NO_PROG;
+	}
+command -v bc >/dev/null 2>&1 ||
+	{ echo >&2 "makebook:  error:  requires bc, but it's not installed";
+	exit $E_NO_PROG;
+	}
 
 # print the version information and exit successfully
 versionfunc ()
@@ -122,7 +132,7 @@ End-of-help
 # define a for dealing with units; convert to bp ()
 unitarg ()
 {
-	if [ ! `echo "$1" | grep '^[\+\|-]*[0-9\.][0-9\.]*\(in\|cm\|pt\|bp\|pc\|$\)'` ]
+	if [ ! `echo "$1" | grep '^[\+\|-]*[0-9\.][0-9\.]*\(in\|cm\|pt\|mm\|bp\|pc\|$\)'` ]
 	then
 		echo "ERROR:  dimension \"$1\" not valid." >&2
 		exit $E_BAD_UNIT
@@ -135,6 +145,10 @@ unitarg ()
 	then
 		OPTARG=`echo "scale=0; ${1%cm} * 28.3464567" | bc`
 		OPTARG=${OPTARG%.*}
+	elif [ `expr match "$1" '.*\(mm\)'` ]
+	then
+		OPTARG=`echo "scale=0; ${1%mm} * 2.83464567" | bc`
+		OPTARG=${OPTARG%.*}
 	elif [ `expr match "$1" '.*\(pt\)'` ]
 	then
 		OPTARG=`echo "scale=0; ${1%pt} / 1.00375" | bc`
@@ -276,7 +290,7 @@ NUM_PAGES=`pdfinfo "$NEW_FILE_NAME" | awk '/Pages:/ {print $2}'`;
 SRC_PAGE_WIDTH=`pdfinfo "$NEW_FILE_NAME" | awk '/Page\ size:/ {print $3}'`;
 SRC_PAGE_HEIGHT=`pdfinfo "$NEW_FILE_NAME" | awk '/Page\ size:/ {print $5}'`;
 # find the number of pages we'll have per signature
-PAGES_PER_SIG=$(($PAGES_PER_SIG * $SECT_TYPE))
+PAGES_PER_SIG=$(dc -e "$PAGES_PER_SIG $SECT_TYPE * p")
 # determine if extra pages will be necessary
 NUM_BLANKS=`expr $NUM_PAGES % $PAGES_PER_SIG`
 if [ $NUM_BLANKS -ne 0 ]
@@ -292,14 +306,13 @@ then
 	echo "\documentclass{article}" > blank.tex
 	echo '\\thispagestyle{empty}' >> blank.tex
 	echo "\usepackage[paperwidth=${SRC_PAGE_WIDTH}bp,paperheight="${SRC_PAGE_HEIGHT}bp"]{geometry}" >> blank.tex
-echo '\\begin{document}' >> blank.tex
-echo "\quad \end{document}" >> blank.tex
+	echo '\\begin{document}' >> blank.tex
+	echo "\quad \\\\end{document}" >> blank.tex
 	if [ $VERBOSE -eq 1 ]
 	then
 		echo "CREATING blank page to fill sections...";
 	fi
 	pdflatex blank.tex > /dev/null 2&>1
-	rm blank.aux blank.log blank.tex
 fi
 # now insert blank pages as needed, preferring the back for
 # odd numbers by default, front if stated
@@ -362,7 +375,7 @@ tmp=`expr $NUM_PAGES + $NUM_BLANKS`
 if [ $VERBOSE -eq 1 ]
 then
 	echo "IMPOSING $NUM_PAGES pages ($tmp with blanks) on
-	$(($NUM_SIGS * $SECT_TYPE)) signature(s) gathered in
+	$(dc -e "$NUM_SIGS $SECT_TYPE * p") signature(s) gathered in
 	sections of $SECT_TYPE signature(s) each...";
 fi
 # arrange the pages for impression on signatures
@@ -377,16 +390,16 @@ do
 	if [ "$SIG_TYPE" = "quarto" ]
 	then
 		# determine size of target page
-        if [ $(echo "$TGT_PAGE_HEIGHT == 0" | bc) -eq 1 ]
+		if [ $TGT_PAGE_HEIGHT -eq 0 ]
 		then
-			TGT_PAGE_HEIGHT=$(echo "$SRC_PAGE_HEIGHT * 2" | bc)
+			TGT_PAGE_HEIGHT=$(dc -e "$SRC_PAGE_HEIGHT 2 * p")
 		fi
-        if [ $(echo "$TGT_PAGE_WIDTH == 0" | bc) -eq 1 ]
+		if [ $TGT_PAGE_WIDTH -eq 0 ]
 		then
-			TGT_PAGE_WIDTH=$(echo "$SRC_PAGE_WIDTH * 2" | bc)
+			TGT_PAGE_WIDTH=$(dc -e "$SRC_PAGE_WIDTH 2 * p")
 		fi
 		# do the rearranging
-		k=$i; n=1; total=$(($SECT_TYPE * 8)); m=$total
+		k=$i; n=1; total=$(dc -e "$SECT_TYPE 8 * p"); m=$total
 		while [ $n -le $SECT_TYPE ]
 		do
 			pdftk "$NEW_FILE_NAME" cat `expr $k + $m - 1` $k \
@@ -418,16 +431,16 @@ do
 	elif [ "$SIG_TYPE" = "folio" ]
 	then
 		# determine size of target page
-        if [ $(echo "$TGT_PAGE_HEIGHT == 0" | bc) -eq 1 ]
+		if [ 1 -eq "$(echo "${TGT_PAGE_HEIGHT} == 0" | bc)" ]
 		then
-			TGT_PAGE_HEIGHT=$(echo "$SRC_PAGE_HEIGHT * 1" | bc)
+			TGT_PAGE_HEIGHT=$(dc -e "$SRC_PAGE_HEIGHT 1 * p")
 		fi
-        if [ $(echo "$TGT_PAGE_WIDTH == 0" | bc) -eq 1 ]
+		if [ 1 -eq "$(echo "${TGT_PAGE_WIDTH} == 0" | bc)" ]
 		then
-			TGT_PAGE_WIDTH=$(echo "$SRC_PAGE_WIDTH * 2" | bc)
+			TGT_PAGE_WIDTH=$(dc -e "$SRC_PAGE_WIDTH 2 * p")
 		fi
 		# do the rearranging
-		k=$i; n=1; total=$(($SECT_TYPE * 4)); m=$total
+		k=$i; n=1; total=$(dc -e "$SECT_TYPE 4 * p"); m=$total
 		while [ $n -le $SECT_TYPE ]
 		do
 			pdftk "$NEW_FILE_NAME" cat `expr $k + $m - 1` \
@@ -458,16 +471,16 @@ do
 	elif [ "$SIG_TYPE" = "octavo" ]
 	then
 		# determine target page dimensions
-        if [ $(echo "$TGT_PAGE_HEIGHT == 0" | bc) -eq 1 ]
+		if [ 1 -eq "$(echo "${TGT_PAGE_HEIGHT} == 0" | bc)" ]
 		then
-			TGT_PAGE_HEIGHT=$(echo "$SRC_PAGE_HEIGHT * 2" | bc)
+			TGT_PAGE_HEIGHT=$(dc -e "$SRC_PAGE_HEIGHT 2 * p")
 		fi
-        if [ $(echo "$TGT_PAGE_WIDTH == 0" | bc) -eq 1 ]
+		if [ 1 -eq "$(echo "${TGT_PAGE_WIDTH} == 0" | bc)" ]
 		then
-			TGT_PAGE_WIDTH=$(echo "$SRC_PAGE_WIDTH * 4" | bc)
+			TGT_PAGE_WIDTH=$(dc -e "$SRC_PAGE_WIDTH 4 * p")
 		fi
 		# do the rearranging
-		k=$i; n=1; total=$(($SECT_TYPE * 16)); m=$total
+		k=$i; n=1; total=$(dc -e "$SECT_TYPE 16 * p"); m=$total
 		while [ $n -le $SECT_TYPE ]
 		do
 			pdftk "$NEW_FILE_NAME" cat `expr $k + 3` \
@@ -503,16 +516,16 @@ do
 	elif [ "$SIG_TYPE" = "sexto" ]
 	then
 		# determine target page dimensions
-        if [ $(echo "$TGT_PAGE_HEIGHT == 0" | bc) -eq 1 ]
+		if [ $TGT_PAGE_HEIGHT -eq 0 ]
 		then
-			TGT_PAGE_HEIGHT=$(echo "$SRC_PAGE_HEIGHT * 3" | bc)
+			TGT_PAGE_HEIGHT=$(dc -e "$SRC_PAGE_HEIGHT 3 * p")
 		fi
-        if [ $(echo "$TGT_PAGE_WIDTH == 0" | bc) -eq 1 ]
+		if [ $TGT_PAGE_WIDTH -eq 0 ]
 		then
-			TGT_PAGE_WIDTH=$(echo "$SRC_PAGE_WIDTH * 2" | bc)
+			TGT_PAGE_WIDTH=$(dc -e "$SRC_PAGE_WIDTH 2 * p")
 		fi
 		# do the rearranging
-		k=$i; n=1; total=$(($SECT_TYPE * 12)); m=$total
+		k=$i; n=1; total=$(dc -e "$SECT_TYPE 12 * p"); m=$total
 		while [ $n -le $SECT_TYPE ]
 		do
 			pdftk "$NEW_FILE_NAME" cat `expr $k + 5` \
@@ -547,16 +560,16 @@ do
 	elif [ "$SIG_TYPE" = "duodecimo" ]
 	then
 		# determine target page dimensions
-        if [ $(echo "$TGT_PAGE_HEIGHT == 0" | bc) -eq 1 ]
+		if [ $TGT_PAGE_HEIGHT -eq 0 ]
 		then
-			TGT_PAGE_HEIGHT=$(($SRC_PAGE_HEIGHT * 3))
+			TGT_PAGE_HEIGHT=$(dc -e "$SRC_PAGE_HEIGHT 3 * p")
 		fi
-        if [ $(echo "$TGT_PAGE_WIDTH == 0" | bc) -eq 1 ]
+		if [ $TGT_PAGE_WIDTH -eq 0 ]
 		then
-			TGT_PAGE_WIDTH=$(($SRC_PAGE_WIDTH * 4))
+			TGT_PAGE_WIDTH=$(dc -e "$SRC_PAGE_WIDTH 4 * p")
 		fi
 		# do the rearranging
-		k=$i; n=1; total=$(($SECT_TYPE * 24)); m=$total
+		k=$i; n=1; total=$(dc -e "$SECT_TYPE 24 * p"); m=$total
 		while [ $n -le $SECT_TYPE ]
 		do
 			pdftk "$NEW_FILE_NAME" cat `expr $k + 8` \
@@ -605,22 +618,32 @@ echo '\\begin{document}' >> ${OUTFILE_NAME%.pdf}.tex
 echo "\includepdf[nup=$NUP,pages=-,turn=false,columnstrict,
 	noautoscale,delta=${HORIZ_DELTA}bp ${VERT_DELTA}bp,
 	offset=${HORIZ_OFFSET}bp ${VERT_OFFSET}bp,scale=${SCALE}]
-	{./"$NEW_FILE_NAME"}\end{document}" >> ${OUTFILE_NAME%.pdf}.tex
+	{./"$NEW_FILE_NAME"}" >> ${OUTFILE_NAME%.pdf}.tex
+echo "\\\\end{document}" >> ${OUTFILE_NAME%.pdf}.tex
 if [ $VERBOSE -eq 1 ]
 then
 	echo "IMPOSING sections..."
 fi
-pdflatex ${OUTFILE_NAME%.pdf}.tex #> /dev/null 2>&1
+pdflatex ${OUTFILE_NAME%.pdf}.tex > /dev/null 2>&1
 if [ $VERBOSE -eq 1 ]
 then
 	echo "CLEANING up..."
 fi
 rm ${OUTFILE_NAME%.pdf}.tex ${OUTFILE_NAME%.pdf}.aux \
 	${OUTFILE_NAME%.pdf}.log "$NEW_FILE_NAME"
+if [ -e "./blank.tex" ]; then
+	rm ./blank.tex
+fi
+if [ -e "./blank.aux" ]; then
+	rm ./blank.aux
+fi
+if [ -e "./blank.log" ]; then
+	rm ./blank.log
+fi
 if [ $VERBOSE -eq 1 ]
 then
 	echo "`expr $NUM_PAGES + $NUM_BLANKS` pages imposed in
-	$(($NUM_SIGS * $SECT_TYPE)) $SIG_TYPE signatures gathered
+	$(dc -e "$NUM_SIGS $SECT_TYPE * p") $SIG_TYPE signatures gathered
 	in sections of $SECT_TYPE signature(s) each and output to
 	${OUTFILE_NAME%.pdf}.pdf."
 fi