diff --git a/beadm b/beadm
index 0b6ab4d..801da39 100755
--- a/beadm
+++ b/beadm
@@ -35,10 +35,6 @@ fi
 __usage() {
   local NAME=${0##*/}
   echo "usage:"
-  echo "  ${NAME} subcommand cmd_options"
-  echo
-  echo "  subcommands:"
-  echo
   echo "  ${NAME} activate beName"
   echo "  ${NAME} create [-e nonActiveBe | -e beName@snapshot] beName"
   echo "  ${NAME} create beName@snapshot"
@@ -62,7 +58,12 @@ __be_exist() { # 1=DATASET
 
 # check if argument is a snapshot
 __be_snapshot() { # 1=DATASET/SNAPSHOT
-  echo "${1}" | grep -q "@"
+  echo "${1}" | grep -q "@" 2> /dev/null
+}
+
+# check if boot environment is mounted
+__be_mounted() { # 1=BE
+  mount 2> /dev/null | grep -q -E "^${1} " 2> /dev/null
 }
 
 # create new boot environment
@@ -76,7 +77,7 @@ __be_new() { # 1=SOURCE 2=TARGET
         do
           if ! zfs list -H -o name ${FS}@${SNAPSHOT} 1> /dev/null 2> /dev/null
           then
-            echo "ERROR: Child snapshot '${FS}@${SNAPSHOT}' does not exists"
+            echo "ERROR: Child snapshot '${FS}@${SNAPSHOT}' does not exist"
             exit 1
           fi
         done
@@ -86,12 +87,10 @@ __be_new() { # 1=SOURCE 2=TARGET
       echo "ERROR: Snapshot '${1}@${2##*/}' already exists"
       exit 1
     fi
-    FMT=$( date "+%Y-%m-%d-%H:%M:%S" )                                  # NEW #
-    if ! zfs snapshot -r ${1}@${FMT} 1> /dev/null 2> /dev/null          # NEW #
-  # if ! zfs snapshot -r ${1}@${2##*/} 1> /dev/null 2> /dev/null        # old #
+    FMT=$( date "+%Y-%m-%d-%H:%M:%S" )
+    if ! zfs snapshot -r ${1}@${FMT} 1> /dev/null 2> /dev/null      # 2##*/ > FMT
     then
-      echo "ERROR: Cannot create snapshot '${1}@${FMT}'"                # NEW #
-    # echo "ERROR: Cannot create snapshot '${1}@${2##*/}'"              # old #
+      echo "ERROR: Cannot create snapshot '${1}@${FMT}'"            # 2##*/ > FMT
       exit 1
     fi
   fi
@@ -114,11 +113,9 @@ EOF
         then
           zfs clone -o canmount=off ${OPTS} ${FS}@${1##*@} ${DATASET}
         else
-        # zfs clone -o canmount=off ${OPTS} ${FS}@${2##*/} ${DATASET}   # old #
-          zfs clone -o canmount=off ${OPTS} ${FS}@${FMT} ${DATASET}     # NEW #
+          zfs clone -o canmount=off ${OPTS} ${FS}@${FMT} ${DATASET} # 2##*/ > FMT
         fi
       done
-  echo "Created successfully"
 }
 
 ROOTFS=$( mount | awk '/ \/ / {print $1}' )
@@ -177,6 +174,7 @@ case ${1} in
           esac
           if [ "${2}" = "-S" ]
           then
+            # do the detailed space calculation [-S]
             USED_ALL=$( zfs list -H -t all -o name,used )
             while read I
             do
@@ -191,18 +189,18 @@ case ${1} in
                 (*E) USED=$( echo ${USED} | awk '{TMP=gsub(/E/,""); TMP=$0*10; gsub(/\..*/,"",TMP); print TMP"00000000000000000"}' ) ;;
                 (*Z) USED=$( echo ${USED} | awk '{TMP=gsub(/Z/,""); TMP=$0*10; gsub(/\..*/,"",TMP); print TMP"00000000000000000000"}' ) ;;
               esac
-              TOTAL=$( echo ${USED} + ${TOTAL} | bc )
+              TOTAL=$( echo | awk -v used=${USED} -v total=${TOTAL} '{print used + total}' )
             done << EOF
 $( zfs list -H -t all -o name,origin -r "${BENAME_STARTS_WITH}/${NAME}" | tr '\t' '\n' | grep -v "^-$" )
 EOF
-            case $( echo "${TOTAL}" | wc -c | tr -c -d '[0-9]\n' ) in
-              (5|6|7)    TOTAL=$( echo ${TOTAL} | awk '{printf (substr($0,0,length($0)-2)/10)"K"}' ); ;;
-              (8|9|10)   TOTAL=$( echo ${TOTAL} | awk '{printf (substr($0,0,length($0)-5)/10)"M"}' ); ;;
-              (11|12|13) TOTAL=$( echo ${TOTAL} | awk '{printf (substr($0,0,length($0)-8)/10)"G"}' ); ;;
-              (14|15|16) TOTAL=$( echo ${TOTAL} | awk '{printf (substr($0,0,length($0)-11)/10)"T"}' ); ;;
-              (17|18|19) TOTAL=$( echo ${TOTAL} | awk '{printf (substr($0,0,length($0)-14)/10)"P"}' ); ;;
-              (20|21|22) TOTAL=$( echo ${TOTAL} | awk '{printf (substr($0,0,length($0)-17)/10)"E"}' ); ;;
-              (23|24|25) TOTAL=$( echo ${TOTAL} | awk '{printf (substr($0,0,length($0)-20)/10)"Z"}' ); ;;
+            case $( echo "${TOTAL}" | awk '{print length($0)}' ) in
+              (4|5|6)    TOTAL=$( echo ${TOTAL} | awk '{printf (substr($0,0,length($0)-2)/10)"K"}' ); ;;
+              (7|8|9)    TOTAL=$( echo ${TOTAL} | awk '{printf (substr($0,0,length($0)-5)/10)"M"}' ); ;;
+              (10|11|12) TOTAL=$( echo ${TOTAL} | awk '{printf (substr($0,0,length($0)-8)/10)"G"}' ); ;;
+              (13|14|15) TOTAL=$( echo ${TOTAL} | awk '{printf (substr($0,0,length($0)-11)/10)"T"}' ); ;;
+              (16|17|18) TOTAL=$( echo ${TOTAL} | awk '{printf (substr($0,0,length($0)-14)/10)"P"}' ); ;;
+              (19|20|21) TOTAL=$( echo ${TOTAL} | awk '{printf (substr($0,0,length($0)-17)/10)"E"}' ); ;;
+              (22|23|24) TOTAL=$( echo ${TOTAL} | awk '{printf (substr($0,0,length($0)-20)/10)"Z"}' ); ;;
             esac
           else
             TOTAL=${USED}
@@ -235,7 +233,6 @@ EOF
             echo "ERROR: Cannot create '${2}' recursive snapshot"
             exit 1
           fi
-          echo "Created successfully"
         else
           __be_new ${ROOTFS} ${POOL}/ROOT/${2}
         fi
@@ -244,6 +241,7 @@ EOF
         __usage
         ;;
     esac
+    echo "Created successfully"
     ;;
 
   (activate) # ----------------------------------------------------------------
@@ -262,7 +260,7 @@ EOF
         MNT=$( mount | grep -E "^${POOL}/ROOT/${2} " | awk '{print $3}' )
         if [ "${MNT}" != "/" ]
         then
-          echo "ERROR: The '${2}' is mounted at '${MNT}'"
+          echo "ERROR: Boot environment '${2}' is mounted at '${MNT}'"
           echo "ERROR: Cannot activate mounted boot environment"
           exit 1
         fi
@@ -308,7 +306,7 @@ EOF
       fi
       if ! zpool set bootfs=${POOL}/ROOT/${2} ${POOL} 2> /dev/null
       then
-        echo "ERROR: Failed to activate '${POOL}/ROOT/${2}'"
+        echo "ERROR: Failed to activate '${2}'"
         exit 1
       fi
     fi
@@ -319,7 +317,7 @@ EOF
         do
           zfs set canmount=noauto ${I}
         done
-    # enable automatic mount for active BE and promote it
+    # enable automatic mount for active boot environment and promote it
     zfs list -H -o name,origin -t filesystem -r ${POOL}/ROOT/${2} \
       | while read I ORIGIN
         do
@@ -355,7 +353,7 @@ EOF
     __be_exist ${POOL}/ROOT/${DESTROY}
     if [ "${BOOTFS}" = "${POOL}/ROOT/${DESTROY}" ]
     then
-      echo "ERROR: '${POOL}/ROOT/${2}' is current active boot environment"
+      echo "ERROR: Cannot destroy active boot environment"
       exit 1
     fi
     case ${CHOICE} in
@@ -366,7 +364,7 @@ EOF
           # destroy desired snapshot
           if ! zfs destroy -r ${POOL}/ROOT/${DESTROY} 1> /dev/null 2> /dev/null
           then
-            echo "ERROR: Snapshot '${2}' is origin for other boot environment(s)"
+            echo "ERROR: Snapshot '${2}' is origin for other boot environment"
             exit 1
           fi
         else
@@ -380,20 +378,39 @@ EOF
                 fi
               done
           # get origins used by destroyed boot environment
-          ORIGINS=$( zfs list -H -t all -o origin -r ${POOL}/ROOT/${DESTROY} | grep -v '^-$' )
+          ORIGIN_SNAPSHOTS=$( zfs list -H -t all -o origin -r ${POOL}/ROOT/${DESTROY} | grep -v '^-$' | awk -F "@" '{print $2}' | sort -u )
           # destroy boot environment
           zfs destroy -r ${POOL}/ROOT/${DESTROY}
-          # destroy origins used by destroyed boot environment
-          echo "${ORIGINS}" \
-            | while read I
+          # promote datasets dependent on origins used by destroyed boot environment
+          ALL_ORIGINS=$( zfs list -H -t all -o name,origin )
+          echo "${ORIGIN_SNAPSHOTS}" \
+            | while read S
               do
-                zfs destroy ${I}
+                echo "${ALL_ORIRINS}" \
+                  | grep "${S}" \
+                  | awk '{print $1}' \
+                  | while read I
+                    do
+                      zfs promote ${I}
+                    done
+              done
+          # destroy origins used by destroyed boot environment
+          ALL_ORIGINS=$( zfs list -H -t all -o origin )
+          echo "${ORIGIN_SNAPSHOTS}" \
+            | while read S
+              do
+                echo "${ALL_ORIRINS}" \
+                  | grep "@${S}$" \
+                  | while read I
+                    do
+                      zfs destroy ${I}
+                    done
               done
         fi
         echo "Destroyed successfully"
         ;;
       (*)
-        echo "'${DESTROY}' has not been destroyed"
+        echo "Boot environment '${DESTROY}' has not been destroyed"
         ;;
     esac
     ;;
@@ -406,7 +423,7 @@ EOF
     __be_exist ${POOL}/ROOT/${2}
     if [ "${BOOTFS}" = "${POOL}/ROOT/${2}" ]
     then
-      echo "ERROR: Renaming the active BE is not supported"
+      echo "ERROR: Renaming active boot environment is not supported"
       exit 1
     fi
     if zfs list -H -o name ${POOL}/ROOT/${3} 2> /dev/null
@@ -419,63 +436,59 @@ EOF
     ;;
 
   (mount) # -------------------------------------------------------------------
-    COMPLETE=1
-    if [ ${#} -eq 1 -o ${#} -eq 2 ]
+    if [ ${#} -eq 1 ]
     then
-      if [ ${2} ]
-      then
-        BE=${2}
-      else
-        zfs list -H -o name -d 1 -r ${POOL}/ROOT \
-          | grep "${POOL}/ROOT/" \
-          | while read NAME
-            do
-              NAME=${NAME##*/}
-              if mount | grep -E "^${POOL}/ROOT/${NAME}" 1> /dev/null 2> /dev/null
-              then
-                echo ${NAME}
-                mount \
-                  | grep -E "^${POOL}/ROOT/${NAME}" \
-                  | awk '{print $1 " " $3}' \
-                  | column -t \
-                  | awk '{print "  " $0}'
-                echo
-              fi
-            done
-        exit 0
-      fi
+      zfs list -H -o name -d 1 -r ${POOL}/ROOT \
+        | grep "${POOL}/ROOT/" \
+        | while read NAME
+          do
+            NAME=${NAME##*/}
+            if mount | grep -q -E "^${POOL}/ROOT/${NAME}" 2> /dev/null
+            then
+              echo ${NAME}
+              mount \
+                | grep -E "^${POOL}/ROOT/${NAME}" \
+                | awk '{print $1 " " $3}' \
+                | column -t \
+                | awk '{print "  " $0}'
+              echo
+            fi
+          done
+      exit 0
+    elif [ ${#} -eq 2 ]
+    then
+      TARGET=$( mktemp -d /tmp/tmp.XXXXXX )
     elif [ ${#} -eq 3 ]
     then
-      BE=${2}
       TARGET=${3}
     else
       __usage
     fi
-    __be_exist "${POOL}/ROOT/${BE}"
-    if mount | grep -E "^${POOL}/ROOT/${BE} " 1> /dev/null 2> /dev/null
+    __be_exist "${POOL}/ROOT/${2}"
+    if __be_mounted "${POOL}/ROOT/${2}"
     then
-      MNT=$( mount | grep -E "^${POOL}/ROOT/${BE} " | awk '{print $3}' )
-      echo "The '${BE}' is already mounted at '${MNT}'"
+      MNT=$( mount | grep -E "^${POOL}/ROOT/${2} " | awk '{print $3}' )
+      echo "Boot environment '${2}' is already mounted at '${MNT}'"
       exit 1
     fi
-    if ! [ ${3} ]
+    if ! mkdir -p ${TARGET} 2> /dev/null
     then
-      TARGET=$( mktemp -d /tmp/tmp.XXXXXX )
-      mkdir -p ${TARGET}
-    fi
-    if ! mount -t zfs ${POOL}/ROOT/${BE} ${TARGET}
-    then
-      echo "ERROR: Cannot mount '${POOL}/ROOT/${BE}' at '${TARGET}' mountpoint"
+      echo "ERROR: Cannot create '${TARGET}' mountpoint"
       exit 1
     fi
-    PREFIX=$( echo ${POOL}/ROOT/${BE}/ | sed 's/\//\\\//g' )
-    zfs list -H -o name,mountpoint -r ${POOL}/ROOT/${BE} \
+    if ! mount -t zfs ${POOL}/ROOT/${2} ${TARGET}
+    then
+      echo "ERROR: Cannot mount '${2}' at '${TARGET}' mountpoint"
+      exit 1
+    fi
+    PREFIX=$( echo ${POOL}/ROOT/${2}/ | sed 's/\//\\\//g' )
+    zfs list -H -o name,mountpoint -r ${POOL}/ROOT/${2} \
       | grep -v "legacy$" \
       | sort -n \
-      | grep -E "^${POOL}/ROOT/${BE}/" \
+      | grep -E "^${POOL}/ROOT/${2}/" \
       | while read FS MOUNTPOINT
         do
-          if [ "{FS}" != "${POOL}/ROOT/${BE}" ]
+          if [ "{FS}" != "${POOL}/ROOT/${2}" ]
           then
             INHERIT=$( zfs get -H -o source mountpoint ${FS} )
             if [ "${INHERIT}" = "local" ]
@@ -503,38 +516,33 @@ EOF
     echo "Mounted successfully on '${TARGET}'"
     ;;
 
-  (umount|unmount) # ------------------------------------------------------------------
-    COMPLETE=1
+  (umount|unmount) # ----------------------------------------------------------
     if [ ${#} -eq 2 ]
     then
-      BE=${2}
-    elif [ ${#} -eq 3 ]
+      # we need this section for argument checking
+      :
+    elif [ ${#} -eq 3 -a "${2}" = "-f" ]
     then
-      BE=${3}
-      if [ "${2}" = "-f" ]
-      then
-        OPTS="-f"
-      else
-        __usage
-      fi
+      OPTS="-f"
+      shift
     else
       __usage
     fi
-    __be_exist "$POOL/ROOT/$BE"
-    if ! mount | grep -E "^${POOL}/ROOT/${BE} " 1> /dev/null 2> /dev/null
+    __be_exist "${POOL}/ROOT/${2}"
+    if ! __be_mounted "${POOL}/ROOT/${2}"
     then
-      echo "The '${BE}' is not mounted"
+      echo "Boot environment '${2}' is not mounted"
       exit 1
     fi
     mount \
-      | grep "^${POOL}/ROOT/${BE}" \
+      | grep "^${POOL}/ROOT/${2}" \
       | awk '{print $1}' \
       | sort -n -r \
       | while read FS
         do
           if ! umount ${OPTS} ${FS} 1> /dev/null 2> /dev/null
           then
-            echo "ERROR: Cannot umount '${FS}'"
+            echo "ERROR: Cannot umount '${FS}' dataset"
             exit 1
           fi
         done