diff --git a/plugins/zfs/zpool_iostat b/plugins/zfs/zpool_iostat
index d9d70bac..957e40d9 100755
--- a/plugins/zfs/zpool_iostat
+++ b/plugins/zfs/zpool_iostat
@@ -5,13 +5,12 @@ if [ "$1" = "autoconf" ]; then
                 exit 0
 fi
 
-zlines=`/sbin/zpool iostat -v| wc -l|sed 's/ //g'`
-ztail=`echo "-"$zlines`
+zlines=$(/sbin/zpool iostat -v | wc -l | sed 's/ //g')
 ztmp=/var/run/munin/zpool_iostat
-zdata=`/sbin/zpool iostat -v 1 1| tail $ztail > $ztmp`
-zlist=`cat $ztmp|gawk '/alloc/ {next}; /avail/ {next}; /raid/ {next}; /mirror/ {next}; { if ( $4 >=0 ) print $1}'`
-zname=`cat $ztmp|gawk '/alloc/ {next}; /avail/ {next}; /raid/ {next}; /mirror/ {next}; { if ( $4 >=0 ) print $1}'|gawk '{gsub("[^a-zA-Z0-9_]", "_", $1); print}'`
-zorder=`for o in $zname; do echo $o'_read '; echo $o'_write '; done`
+/sbin/zpool iostat -v 1 1 | tail "-$zlines" > "$ztmp"
+zlist=$(gawk '/alloc/ {next}; /avail/ {next}; /raid/ {next}; /mirror/ {next}; { if ( $4 >=0 ) print $1}' "$ztmp")
+zname=$(gawk '/alloc/ {next}; /avail/ {next}; /raid/ {next}; /mirror/ {next}; { if ( $4 >=0 ) print $1}' "$ztmp" | gawk '{gsub("[^a-zA-Z0-9_]", "_", $1); print}')
+zorder=$(for o in $zname; do echo "${o}_read "; echo "${o}_write "; done)
 
 if [ "$1" = "config" ]; then
         echo 'graph_title zpool iostat'
@@ -20,29 +19,29 @@ if [ "$1" = "config" ]; then
         echo 'graph_category fs'
         echo 'graph_scale no'
         echo 'graph_info This graph shows zpool iostat'
-	echo 'graph_order '$zorder
-	echo $zlist | tr ' ' '\n' | while read i; do
-                case $i in
-                *) name=`echo $i | gawk '{ gsub("[^a-zA-Z0-9_]", "_", $1); print }'` ;;
+	echo "graph_order $zorder"
+	echo "$zlist" | tr ' ' '\n' | while read -r i; do
+                case "$i" in
+			*) name=$(echo "$i" | gawk '{ gsub("[^a-zA-Z0-9_]", "_", $1); print }') ;;
                 esac
-                echo $name'_read.label '$i
-		echo $name'_read.type GAUGE'
-		echo $name'_read.graph no'
-		echo $name'_write.label '$i
-		echo $name'_write.type GAUGE'
-		echo $name'_write.negative '$name'_read'
+                echo "${name}_read.label $i"
+		echo "${name}_read.type GAUGE"
+		echo "${name}_read.graph no"
+		echo "${name}_write.label $i"
+		echo "${name}_write.type GAUGE"
+		echo "${name}_write.negative ${name}_read"
         done
         exit 0
 fi
-echo $zlist | tr ' ' '\n' | while read iz; do
-	zlabel=`echo $iz|gawk '{print $1}'`
-	case $iz in
-	*) name=`echo $iz | gawk '{ gsub("[^a-zA-Z0-9_]", "_", $1); print $1 }'` ;;
+echo "$zlist" | tr ' ' '\n' | while read -r iz; do
+	zlabel=$(echo "$iz" | gawk '{print $1}')
+	case "$iz" in
+		*) name=$(echo "$iz" | gawk '{ gsub("[^a-zA-Z0-9_]", "_", $1); print $1 }') ;;
 	esac
-	echo -n $name'_read.value '
+	echo -n "${name}_read.value "
 	gawk '{ if ($1 == "'"$zlabel"'") print $6; }' "$ztmp"|gawk '/M/ {print strtonum($1)*1000}; /K/ {print strtonum($1)}; /[0-9]$/ {print int($1)/1000}'
-	echo -n $name'_write.value '
+	echo -n "${name}_write.value "
 	gawk '{ if ($1 == "'"$zlabel"'") print $7; }' "$ztmp"|gawk '/M/ {print strtonum($1)*1000}; /K/ {print strtonum($1)}; /[0-9]$/ {print int($1)/1000}'
 done
 
-rm $ztmp; touch $ztmp
+rm "$ztmp"; touch "$ztmp"