diff --git a/check_mountpoints.sh b/check_mountpoints.sh
index 30e75ee..4b21501 100755
--- a/check_mountpoints.sh
+++ b/check_mountpoints.sh
@@ -104,9 +104,9 @@
 # --------------------------------------------------------------------
 # configuration
 # --------------------------------------------------------------------
-PROGNAME=$(basename $0)
+PROGNAME=$(basename "$0")
 ERR_MESG=()
-LOGGER="`which logger` -i -p kern.warn -t"
+LOGGER="$(which logger) -i -p kern.warn -t"
 
 AUTO=0
 AUTOIGNORE=0
@@ -120,7 +120,8 @@ EXCLUDE=none
 export PATH="/bin:/usr/local/bin:/sbin:/usr/bin:/usr/sbin:/usr/sfw/bin"
 LIBEXEC="/opt/nagios/libexec /usr/lib64/nagios/plugins /usr/lib/nagios/plugins /usr/lib/monitoring-plugins /usr/local/nagios/libexec /usr/local/icinga/libexec /usr/local/libexec /opt/csw/libexec/nagios-plugins /opt/plugins /usr/local/libexec/nagios/"
 for i in ${LIBEXEC} ; do
-  [ -r ${i}/utils.sh ] && . ${i}/utils.sh
+  # shellcheck source=/dev/null
+  [ -r "${i}"/utils.sh ] && . "${i}"/utils.sh
 done
 
 if [ -z "$STATE_OK" ]; then
@@ -128,7 +129,7 @@ if [ -z "$STATE_OK" ]; then
   exit 1
 fi
 
-KERNEL=`uname -s`
+KERNEL=$(uname -s)
 case $KERNEL in
   # For solaris FSF=4 MF=3 FSTAB=/etc/vfstab MTAB=/etc/mnttab gnu grep and bash required
   SunOS) FSF=4
@@ -137,8 +138,8 @@ case $KERNEL in
          NOAUTOSTR=no
          FSTAB=/etc/vfstab
          MTAB=/etc/mnttab
-         GREP=ggrep
-         STAT=stat
+         GREP="ggrep"
+         STAT="stat"
          ;;
   HP-UX) FSF=3
          MF=2
@@ -146,17 +147,17 @@ case $KERNEL in
          NOAUTOSTR=noauto
          FSTAB=/etc/fstab
          MTAB=/dev/mnttab
-         GREP=grep
-         STAT=stat
+         GREP="grep"
+         STAT="stat"
          ;;
   FreeBSD) FSF=3
          MF=2
          OF=4
          NOAUTOSTR=noauto
          FSTAB=/etc/fstab
-         MTAB=none
-         GREP=grep
-         STAT=stat
+         MTAB="none"
+         GREP="grep"
+         STAT="stat"
 	 ;;
   *)     FSF=3
          MF=2
@@ -164,8 +165,8 @@ case $KERNEL in
          NOAUTOSTR=noauto
          FSTAB=/etc/fstab
          MTAB=/proc/mounts
-         GREP=grep
-         STAT=stat
+         GREP="grep"
+         STAT="stat"
          ;;
 esac
 
@@ -180,7 +181,7 @@ TIME_TILL_STALE=3
 # functions
 # --------------------------------------------------------------------
 function log() {
-        $LOGGER ${PROGNAME} "$@";
+        $LOGGER "${PROGNAME}" "$@";
 }
 
 function usage() {
@@ -222,11 +223,11 @@ function print_help() {
 # Format is dev mountpoint filesystem
 function make_mtab() {
 	mtab=$(mktemp)
-	mount > $mtab
-	sed -i '' 's/ on / /' $mtab
-	sed -i '' 's/ (/ /' $mtab
-	sed -i '' 's/,.*/ /' $mtab
-	echo $mtab
+	mount > "$mtab"
+	sed -i '' 's/ on / /' "$mtab"
+	sed -i '' 's/ (/ /' "$mtab"
+	sed -i '' 's/,.*/ /' "$mtab"
+	echo "$mtab"
 }
 
 
@@ -236,7 +237,7 @@ function make_mtab() {
 
 if [ $# -eq 0 ]; then
         usage
-        exit $STATE_CRITICAL
+        exit "$STATE_CRITICAL"
 fi
 
 while [ "$1" != "" ]
@@ -244,23 +245,23 @@ do
         case "$1" in
                 -a) AUTO=1; shift;;
                 -A) AUTO=1; AUTOIGNORE=1; shift;;
-		-E) EXCLUDE=$2; shift 2;;
+		-E) EXCLUDE="$2"; shift 2;;
                 -o) NOAUTOIGNORE=1; shift;;
-                --help) print_help; exit $STATE_OK;;
-                -h) print_help; exit $STATE_OK;;
-                -m) MTAB=$2; shift 2;;
-                -f) FSTAB=$2; shift 2;;
-                -N) FSF=$2; shift 2;;
-                -M) MF=$2; shift 2;;
-                -O) OF=$2; shift 2;;
-                -T) TIME_TILL_STALE=$2; shift 2;;
+                --help) print_help; exit "$STATE_OK";;
+                -h) print_help; exit "$STATE_OK";;
+                -m) MTAB="$2"; shift 2;;
+                -f) FSTAB="$2"; shift 2;;
+                -N) FSF="$2"; shift 2;;
+                -M) MF="$2"; shift 2;;
+                -O) OF="$2"; shift 2;;
+                -T) TIME_TILL_STALE="$2"; shift 2;;
                 -i) IGNOREFSTAB=1; shift;;
                 -w) WRITETEST=1; shift;;
                 -L) LINKOK=1; shift;;
-                -e) DFARGS=$2; shift 2;; 
-                -t) FSTYPE=$2; shift 2;;
+                -e) DFARGS="$2"; shift 2;; 
+                -t) FSTYPE="$2"; shift 2;;
                 /*) MPS="${MPS} $1"; shift;;
-                *) usage; exit $STATE_UNKNOWN;;
+                *) usage; exit "$STATE_UNKNOWN";;
         esac
 done
 
@@ -268,57 +269,57 @@ done
 
 if [ -x '/sbin/zfs' ]; then
 	TMPTAB=$(mktemp)
-	cat ${FSTAB} > ${TMPTAB}
+	cat "${FSTAB}" > "${TMPTAB}"
 	for DS in $(zfs list -H -o name -t filesystem); do
-		MP=$(zfs get -H mountpoint ${DS} |awk '{print $3}')
+		MP="$(zfs get -H mountpoint "${DS}" |awk '{print $3}')"
 		# mountpoint ~ "none|legacy|-"
 		if [ ! -d "$MP" ]; then
 			continue
 		fi
-		if [ $(zfs get -H canmount ${DS} |awk '{print $3}') == 'off' ]; then
+		if [ "$(zfs get -H canmount "${DS}" |awk '{print $3}')" == 'off' ]; then
 			continue
 		fi
 		case $KERNEL in
 			SunOS)
-			if [ $(zfs get -H zoned ${DS} |awk '{print $3}') == 'on' ]; then
+			if [ "$(zfs get -H zoned "${DS}" |awk '{print $3}')" == 'on' ]; then
 				continue
 			fi
 			;;
 			FreeBSD)
-			if [ $(zfs get -H jailed ${DS} |awk '{print $3}') == 'on' ]; then
+			if [ "$(zfs get -H jailed "${DS}" |awk '{print $3}')" == 'on' ]; then
 				continue
 			fi
 			;;
 		esac
-		RO=$(zfs get -H readonly ${DS} |awk '($3 == "on"){print "ro"}')
+		RO="$(zfs get -H readonly "${DS}" |awk '($3 == "on"){print "ro"}')"
 		[ -z "$RO" ] &&  RO='rw'
-		echo -e "$DS\t$MP\tzfs\t$RO\t0\t0" >> ${TMPTAB}
+		echo -e "$DS\t$MP\tzfs\t$RO\t0\t0" >> "${TMPTAB}"
 	done
-	FSTAB=${TMPTAB}
+	FSTAB="${TMPTAB}"
 fi
 
-if [ ${AUTO} -eq 1 ]; then
-        if [ ${NOAUTOIGNORE} -eq 1 ]; then
-                 NOAUTOCOND='!index($'${OF}',"'${NOAUTOSTR}'")'
+if [ "${AUTO}" -eq 1 ]; then
+        if [ "${NOAUTOIGNORE}" -eq 1 ]; then
+                 NOAUTOCOND='!index($'"${OF}"',"'"${NOAUTOSTR}"'")'
         fi
 	if [ "${EXCLUDE}" == "none" ]; then
-		MPS=`${GREP} -v '^#' ${FSTAB} | awk '{if ('${NOAUTOCOND}'&&($'${FSF}'=="ext2" || $'${FSF}'=="ext3" || $'${FSF}'=="xfs" || $'${FSF}'=="auto" || $'${FSF}'=="ext4" || $'${FSF}'=="nfs" || $'${FSF}'=="nfs4" || $'${FSF}'=="davfs" || $'${FSF}'=="cifs" || $'${FSF}'=="fuse" || $'${FSF}'=="glusterfs" || $'${FSF}'=="ocfs2" || $'${FSF}'=="lustre" || $'${FSF}'=="ufs" || $'${FSF}'=="zfs" || $'${FSF}'=="ceph" || $'${FSF}'=="btrfs" || $'${FSF}'=="yas3fs"))print $'${MF}'}' | sed -e 's/\/$//i' | tr '\n' ' '`
+		MPS=$(${GREP} -v '^#' "${FSTAB}" | awk '{if ('"${NOAUTOCOND}"'&&($'"${FSF}"'=="ext2" || $'"${FSF}"'=="ext3" || $'"${FSF}"'=="xfs" || $'"${FSF}"'=="auto" || $'"${FSF}"'=="ext4" || $'"${FSF}"'=="nfs" || $'"${FSF}"'=="nfs4" || $'"${FSF}"'=="davfs" || $'"${FSF}"'=="cifs" || $'"${FSF}"'=="fuse" || $'"${FSF}"'=="glusterfs" || $'"${FSF}"'=="ocfs2" || $'"${FSF}"'=="lustre" || $'"${FSF}"'=="ufs" || $'"${FSF}"'=="zfs" || $'"${FSF}"'=="ceph" || $'"${FSF}"'=="btrfs" || $'"${FSF}"'=="yas3fs"))print $'"${MF}"'}' | sed -e 's/\/$//i' | tr '\n' ' ')
 	else
-		MPS=`${GREP} -v '^#' ${FSTAB} | ${GREP} -v ${EXCLUDE} | awk '{if ('${NOAUTOCOND}'&&($'${FSF}'=="ext2" || $'${FSF}'=="ext3" || $'${FSF}'=="xfs" || $'${FSF}'=="auto" || $'${FSF}'=="ext4" || $'${FSF}'=="nfs" || $'${FSF}'=="nfs4" || $'${FSF}'=="davfs" || $'${FSF}'=="cifs" || $'${FSF}'=="fuse" || $'${FSF}'=="glusterfs" || $'${FSF}'=="ocfs2" || $'${FSF}'=="lustre" || $'${FSF}'=="ufs" || $'${FSF}'=="zfs" || $'${FSF}'=="ceph" || $'${FSF}'=="btrfs" || $'${FSF}'=="yas3fs"))print $'${MF}'}' | sed -e 's/\/$//i' | tr '\n' ' '`
+		MPS=$(${GREP} -v '^#' "${FSTAB}" | ${GREP} -v "${EXCLUDE}" | awk '{if ('"${NOAUTOCOND}"'&&($'"${FSF}"'=="ext2" || $'"${FSF}"'=="ext3" || $'"${FSF}"'=="xfs" || $'"${FSF}"'=="auto" || $'"${FSF}"'=="ext4" || $'"${FSF}"'=="nfs" || $'"${FSF}"'=="nfs4" || $'"${FSF}"'=="davfs" || $'"${FSF}"'=="cifs" || $'"${FSF}"'=="fuse" || $'"${FSF}"'=="glusterfs" || $'"${FSF}"'=="ocfs2" || $'"${FSF}"'=="lustre" || $'"${FSF}"'=="ufs" || $'"${FSF}"'=="zfs" || $'"${FSF}"'=="ceph" || $'"${FSF}"'=="btrfs" || $'"${FSF}"'=="yas3fs"))print $'"${MF}"'}' | sed -e 's/\/$//i' | tr '\n' ' ')
 	fi
 fi
 
 if [ -z "${MPS}"  ] && [ ${AUTOIGNORE} -eq 1 ] ; then
 		echo "OK: no external mounts were found in ${FSTAB}"
-		exit $STATE_OK
+		exit "$STATE_OK"
 elif [ -z "${MPS}"  ]; then
         log "ERROR: no mountpoints given!"
         echo "ERROR: no mountpoints given!"
         usage
-        exit $STATE_UNKNOWN
+        exit "$STATE_UNKNOWN"
 fi
 
-if [ ! -f /proc/mounts -a "${MTAB}" == "/proc/mounts" ]; then
+if [ ! -f /proc/mounts ] && [ "${MTAB}" == "/proc/mounts" ]; then
         log "CRIT: /proc wasn't mounted!"
         mount -t proc proc /proc
         ERR_MESG[${#ERR_MESG[*]}]="CRIT: mounted /proc $?"
@@ -331,13 +332,13 @@ fi
 if [ ! -e "${MTAB}" ]; then
         log "CRIT: ${MTAB} doesn't exist!"
         echo "CRIT: ${MTAB} doesn't exist!"
-        exit $STATE_CRITICAL
+        exit "$STATE_CRITICAL"
 fi
 
 if [ -n "${FSTYPE}" ]; then
         # split on commas
         oIFS=$IFS
-        IFS=, read -a fstypes <<<"${FSTYPE}"
+        IFS=, read -ra fstypes <<<"${FSTYPE}"
         IFS=$oIFS
 fi
 
@@ -353,27 +354,27 @@ mpidx=0
 for MP in ${MPS} ; do
         ## If its an OpenVZ Container or -a Mode is selected skip fstab check.
         ## -a Mode takes mounts from fstab, we do not have to check if they exist in fstab ;)
-        if [ ! -f /proc/vz/veinfo -a ${AUTO} -ne 1 -a ${IGNOREFSTAB} -ne 1 ]; then
-                if [ -z "$( "${GREP}" -v '^#' "${FSTAB}" | awk '$'${MF}' == "'${MP}'" {print $'${MF}'}' )" ]; then
+        if [ ! -f /proc/vz/veinfo ] && [ ${AUTO} -ne 1 ] && [ ${IGNOREFSTAB} -ne 1 ]; then
+                if [ -z "$( "${GREP}" -v '^#' "${FSTAB}" | awk '$'"${MF}"' == "'"${MP}"'" {print $'"${MF}"'}' )" ]; then
                         log "CRIT: ${MP} doesn't exist in /etc/fstab"
                         ERR_MESG[${#ERR_MESG[*]}]="${MP} doesn't exist in fstab ${FSTAB}"
                 fi
         fi
 
         ## check kernel mounts
-        if [ -z "$( awk '$'${MF}' == "'${MP}'" {print $'${MF}'}' "${MTAB}" )" ]; then
+        if [ -z "$( awk '$'"${MF}"' == "'"${MP}"'" {print $'"${MF}"'}' "${MTAB}" )" ]; then
         ## if a softlink is not an adequate replacement
-        	if [ -z "$LINKOK" -o ! -L ${MP} ]; then
+        	if [ -z "$LINKOK" ] || [ ! -L "${MP}" ]; then
                 	log "CRIT: ${MP} is not mounted"
                 	ERR_MESG[${#ERR_MESG[*]}]="${MP} is not mounted"
                 fi
         fi
 
         ## check if it stales
-        df -k ${DFARGS} ${MP} &>/dev/null &
+        df -k "${DFARGS}" "${MP}" &>/dev/null &
         DFPID=$!
         disown
-        for (( i=1 ; i<$TIME_TILL_STALE ; i++ )) ; do
+        for (( i=1 ; i<TIME_TILL_STALE ; i++ )) ; do
                 if ps -p $DFPID > /dev/null ; then
                         sleep 1
                 else
@@ -381,12 +382,12 @@ for MP in ${MPS} ; do
                 fi
         done
         if ps -p $DFPID > /dev/null ; then
-                $(kill -s SIGTERM $DFPID &>/dev/null)
+                kill -s SIGTERM $DFPID &>/dev/null
                 ERR_MESG[${#ERR_MESG[*]}]="${MP} did not respond in $TIME_TILL_STALE sec. Seems to be stale."
         else
         ## if it not stales, check if it is a directory
 	        ISRW=0
-                if [ ! -d ${MP} ]; then
+                if [ ! -d "${MP}" ]; then
                         log "CRIT: ${MP} doesn't exist on filesystem"
                         ERR_MESG[${#ERR_MESG[*]}]="${MP} doesn't exist on filesystem"
                 ## if wanted, check if it is writable
@@ -395,7 +396,7 @@ for MP in ${MPS} ; do
 		## in auto mode first check if it's readonly
 		elif [ ${WRITETEST} -eq 1 ] && [ ${AUTO} -eq 1 ]; then
 			ISRW=1
-			for OPT in $(${GREP} -w ${MP} ${FSTAB} |awk '{print $4}'| sed -e 's/,/ /g'); do
+			for OPT in $(${GREP} -w "${MP}" "${FSTAB}" |awk '{print $4}'| sed -e 's/,/ /g'); do
 				if [ "$OPT" == 'ro' ]; then
 					ISRW=0
                                         log "CRIT: ${TOUCHFILE} is not mounted as writable."
@@ -405,9 +406,9 @@ for MP in ${MPS} ; do
 		fi
 		if [ ${ISRW} -eq 1 ]; then
 			TOUCHFILE=${MP}/.mount_test_from_$(hostname)_$(date +%Y-%m-%d--%H-%M-%S).$RANDOM.$$
-			touch ${TOUCHFILE} &>/dev/null &
+			touch "${TOUCHFILE}" &>/dev/null &
 			TOUCHPID=$!
-			for (( i=1 ; i<$TIME_TILL_STALE ; i++ )) ; do
+			for (( i=1 ; i<TIME_TILL_STALE ; i++ )) ; do
 				if ps -p $TOUCHPID > /dev/null ; then
 					sleep 1
 				else
@@ -415,15 +416,15 @@ for MP in ${MPS} ; do
 				fi
 			done
 			if ps -p $TOUCHPID > /dev/null ; then
-				$(kill -s SIGTERM $TOUCHPID &>/dev/null)
+				kill -s SIGTERM "$TOUCHPID" &>/dev/null
 				log "CRIT: ${TOUCHFILE} is not writable."
 				ERR_MESG[${#ERR_MESG[*]}]="Could not write in ${MP} in $TIME_TILL_STALE sec. Seems to be stale."
 			else
-				if [ ! -f ${TOUCHFILE} ]; then
+				if [ ! -f "${TOUCHFILE}" ]; then
 					log "CRIT: ${TOUCHFILE} is not writable."
 					ERR_MESG[${#ERR_MESG[*]}]="Could not write in ${MP}."
 				else
-					rm ${TOUCHFILE} &>/dev/null
+					rm "${TOUCHFILE}" &>/dev/null
 				fi
 			fi
                 fi
@@ -438,8 +439,7 @@ for MP in ${MPS} ; do
             continue
         fi
 
-        rfstype=$(${STAT} -f --printf='%T' "${MP}")
-        if [ $? -ne 0 ]
+        if ! rfstype="$(${STAT} -f --printf='%T' "${MP}")";
         then
             log "CRIT: Fail to fetch FS type for ${MP}"
             ERR_MESG[${#ERR_MESG[*]}]="Fail to fetch FS type for ${MP}"
@@ -456,20 +456,20 @@ done
 
 # Remove temporary files
 if [[ "${MTAB}" =~ "/tmp" ]]; then
-       rm -f ${MTAB}
+       rm -f "${MTAB}"
 fi
 if [[ "${FSTAB}" =~ "/tmp" ]]; then
-       rm -f ${FSTAB}
+       rm -f "${FSTAB}"
 fi
 
 if [ ${#ERR_MESG[*]} -ne 0 ]; then
         echo -n "CRITICAL: "
         for element in "${ERR_MESG[@]}"; do
-                echo -n ${element}" ; "
+                echo -n "${element}"" ; "
         done
         echo
-        exit $STATE_CRITICAL
+        exit "$STATE_CRITICAL"
 fi
 
 echo "OK: all mounts were found (${MPS})"
-exit $STATE_OK
+exit "$STATE_OK"