diff --git a/lnxrouter b/lnxrouter
index 4dc7af3..2fd90e6 100755
--- a/lnxrouter
+++ b/lnxrouter
@@ -1,7 +1,7 @@
 #!/bin/bash
 
-VERSION=0.6.7
-PROGNAME="$(basename $0)"
+VERSION=0.7.3a
+PROGNAME="$(basename "$0")"
 
 export LC_ALL=C
 
@@ -88,8 +88,7 @@ Options:
                             Using this you can't use same wlan interface
                             for both Internet and AP
     --virt-name <name>      Set name of virtual interface
-    -c <channel>            Channel number (default: 1)
-    --force_channel         Force the use of channel provided by -c flag
+    -c <channel>            Specify channel (default: use current, or 1 / 36)
     --country <code>        Set two-letter country code for regularity
                             (example: US)
     --freq-band <GHz>       Set frequency band: 2.4 or 5 (default: 2.4)
@@ -104,29 +103,42 @@ Options:
     --hostapd-debug <level> 1 or 2. Passes -d or -dd to hostapd
     --isolate-clients       Disable wifi communication between clients
     --no-haveged            Do not run haveged automatically when needed
-    --hs20                  Enable Hotspot 2.0 (Make sure your hostapd build supports it)
+    --hs20                  Enable Hotspot 2.0
 
-    WiFi 4(802.11N) Config:
-    --ieee80211n            Enable IEEE 802.11n (HT)
-    --use_ht                Enable High Throughput mode
-    --ht_capab <HT>         HT capabilities (default: [HT40+])
+    WiFi 4 (802.11n) configs:
+    --wifi4                 Enable IEEE 802.11n (HT)
+    --req-ht                Require station HT (High Throughput) mode
+    --ht-capab <HT caps>    HT capabilities (default: [HT40+])
 
-    WiFi 5(802.11AC) Config:
-    --ieee80211ac           Enable IEEE 802.11ac (VHT)
-    --use_vht               Enable Very High Thoughtput mode
-    --vht_capab <VHT>       VHT capabilities
-    --vht_channel_width <index> 
-                            Index of VHT Channel Width:
+    WiFi 5 (802.11ac) configs:
+    --wifi5                 Enable IEEE 802.11ac (VHT)
+    --req-vht               Require station VHT (Very High Thoughtput) mode
+    --vht-capab <VHT caps>  VHT capabilities
+    
+    --vht-ch-width <index>  Index of VHT channel width:
                                 0 for 20MHz or 40MHz (default)
                                 1 for 80MHz
                                 2 for 160MHz
                                 3 for 80+80MHz (Non-contigous 160MHz)    
-    --seg0_center_freq_idx <channel>
-                            Channel index of Center frequency for primary segment, use with --vht_channel_width
-    --seg1_center_freq_idx <channel>
-                            Channel index of Center frequency for secondary (second 80MHz) segment, use with --vht_channel_width=3
-                            Pick above 2 values from the F0 index column from the 5GHz table in https://en.wikipedia.org/wiki/List_of_WLAN_channels#5_GHz_(802.11a/h/n/ac/ax)
-
+    --vht-seg0-ch <channel> Channel index of VHT center frequency for primary 
+                            segment. Use with '--vht-ch-width'
+    --vht-seg1-ch <channel> Channel index of VHT center frequency for secondary
+                            (second 80MHz) segment. Use with '--vht-ch-width 3'
+   
+    WiFi 6 (802.11ax) configs:
+    --wifi6                 Enable IEEE 802.11ax (HE)
+    --req-he                Require station HE (High Efficiency) mode
+    
+    --he-ch-width <index>   Index of HE channel width:
+                                0 for 20MHz or 40MHz (default)
+                                1 for 80MHz
+                                2 for 160MHz
+                                3 for 80+80MHz (Non-contigous 160MHz)    
+    --he-seg0-ch <channel>  Channel index of HE center frequency for primary
+                            segment. Use with '--he-ch-width'
+    --he-seg1-ch <channel>  Channel index of HE center frequency for secondary
+                            (second 80MHz) segment. Use with '--he-ch-width 3'
+ 
   Instance managing:
     --daemon                Run in background
     -l, --list-running      Show running instances
@@ -196,7 +208,6 @@ define_global_variables(){
     HIDDEN=0 # hidden wifi hotspot
     WIFI_IFACE=
     CHANNEL=default 
-    FORCECHANNEL=0 # Forces channel provided by -c flag
     HOTSPOT20=0 # For enabling Hotspot 2.0
     WPA_VERSION=2
     MAC_FILTER=0
@@ -205,11 +216,16 @@ define_global_variables(){
     REQUIREHT=0
     IEEE80211AC=0
     REQUIREVHT=0
+    IEEE80211AX=0
+    REQUIRE_HE=0
     HT_CAPAB='[HT40+]'
     VHT_CAPAB=
     VHTCHANNELWIDTH=0
     VHTSEG0CHINDEX=0
     VHTSEG1CHINDEX=0
+    HECHANNELWIDTH=0
+    HESEG0CHINDEX=0
+    HESEG1CHINDEX=0
     DRIVER=nl80211
     NO_VIRT=0 # not use virtual interface
     COUNTRY=
@@ -397,10 +413,6 @@ parse_user_options(){
                 CHANNEL="$1"
                 shift
                 ;;
-            --force_channel)
-                shift
-                FORCECHANNEL=1
-                ;;
             --hs20)
                 shift
                 HOTSPOT20=1
@@ -412,47 +424,70 @@ parse_user_options(){
                 shift
                 ;;
 
-            --ieee80211n)
+            --wifi4|--ieee80211n)
                 shift
                 IEEE80211N=1
                 ;;
-            --use_ht)
+            --req-ht|--require-ht)
                 shift
                 REQUIREHT=1
                 ;;
-            --ieee80211ac)
+            --wifi5|--ieee80211ac)
                 shift
                 IEEE80211AC=1
                 ;;
-            --use_vht)
+            --wifi6|--ieee80211ax)
+                shift
+                IEEE80211AX=1
+                ;;
+            --req-he|--require-he)
+                shift
+                REQUIRE_HE=1
+                ;;
+            --req-vht|--require-vht)
                 shift
                 REQUIREVHT=1
                 ;;
-            --ht_capab)
+            --ht-capab)
                 shift
                 HT_CAPAB="$1"
                 shift
                 ;;
-            --vht_capab)
+            --vht-capab)
                 shift
                 VHT_CAPAB="$1"
                 shift
                 ;;
-            --vht_channel_width)
+            --vht-ch-width|--vht-channel-width)
                 shift
                 VHTCHANNELWIDTH="$1"
                 shift
                 ;;
-            --seg0_center_freq_idx)
+            --vht-seg0-ch|--vht-seg0-channel)
                 shift
                 VHTSEG0CHINDEX="$1"
                 shift
                 ;;
-            --seg1_center_freq_idx)
+            --vht-seg1-ch|--vht-seg1-channel)
                 shift
                 VHTSEG1CHINDEX="$1"
                 shift
                 ;;
+            --he-ch-width|--he-channel-width)
+                shift
+                HECHANNELWIDTH="$1"
+                shift
+                ;;
+            --he-seg0-ch|--he-seg0-channel)
+                shift
+                HESEG0CHINDEX="$1"
+                shift
+                ;;
+            --he-seg1-ch|--he-seg1-channel)
+                shift
+                HESEG1CHINDEX="$1"
+                shift
+                ;;
             --driver)
                 shift
                 DRIVER="$1"
@@ -484,9 +519,9 @@ parse_user_options(){
                 ;;
             --hostapd-debug)
                 shift
-                if [ "x$1" = "x1" ]; then
+                if [ "$1" = "1" ]; then
                     HOSTAPD_DEBUG_ARGS="-d"
-                elif [ "x$1" = "x2" ]; then
+                elif [ "$1" = "2" ]; then
                     HOSTAPD_DEBUG_ARGS="-dd"
                 else
                     printf "Error: argument for --hostapd-debug expected 1 or 2, got %s\n" "$1"
@@ -543,8 +578,8 @@ sep_ip_port() {
     if (echo "$INPUT" | grep '\.' >/dev/null 2>&1) ;then  
         if (echo "$INPUT" | grep ':' >/dev/null 2>&1) ;then
             # ipv4 + port
-            IP="$(echo $INPUT | cut -d: -f1)"
-            PORT="$(echo $INPUT | cut -d: -f2)"
+            IP="$(echo "$INPUT" | cut -d: -f1)"
+            PORT="$(echo "$INPUT" | cut -d: -f2)"
         else
             # ipv4
             IP="$INPUT"
@@ -552,11 +587,11 @@ sep_ip_port() {
     elif (echo "$INPUT" | grep '\]' >/dev/null 2>&1) ;then 
         if (echo "$INPUT" | grep '\]\:' >/dev/null 2>&1) ;then
             # ipv6 + port
-            IP="$(echo $INPUT | cut -d']' -f1 | cut -d'[' -f2)"
-            PORT="$(echo $INPUT | cut -d']' -f2 |cut -d: -f2)"
+            IP="$(echo "$INPUT" | cut -d']' -f1 | cut -d'[' -f2)"
+            PORT="$(echo "$INPUT" | cut -d']' -f2 |cut -d: -f2)"
         else
             # ipv6
-            IP="$(echo $INPUT | cut -d']' -f1 | cut -d'[' -f2)"
+            IP="$(echo "$INPUT" | cut -d']' -f1 | cut -d'[' -f2)"
         fi
     else 
         # port
@@ -585,10 +620,10 @@ get_interface_phy_device() { # only for wifi interface
             echo "$1"
             return 0
         elif [[ -e "$x/device/net/$1" ]]; then
-            echo ${x##*/}
+            echo "${x##*/}"
             return 0
         elif [[ -e "$x/device/net:$1" ]]; then
-            echo ${x##*/}
+            echo "${x##*/}"
             return 0
         fi
     done
@@ -600,13 +635,13 @@ get_adapter_info() { # only for wifi interface
     local iPHY
     iPHY=$(get_interface_phy_device "$1")
     [[ $? -ne 0 ]] && return 1
-    iw phy $iPHY info
+    iw phy "$iPHY" info
 }
 
 get_adapter_kernel_module() {
     local MODULE
     MODULE=$(readlink -f "/sys/class/net/$1/device/driver/module")
-    echo ${MODULE##*/}
+    echo "${MODULE##*/}"
 }
 
 can_be_sta_and_ap() {
@@ -637,18 +672,14 @@ can_transmit_to_channel() {
     CHANNEL_NUM=$2
 
     if [[ $USE_IWCONFIG -eq 0 ]]; then
-        if [[ $FREQ_BAND == 2.4 ]]; then
-            CHANNEL_INFO=$(get_adapter_info ${IFACE} | grep " 24[0-9][0-9] MHz \[${CHANNEL_NUM}\]")
-        else
-            CHANNEL_INFO=$(get_adapter_info ${IFACE} | grep " \(49[0-9][0-9]\|5[0-9]\{3\}\) MHz \[${CHANNEL_NUM}\]")
-        fi
+        CHANNEL_INFO=$(get_adapter_info "${IFACE}" | grep -E " [0-9]+(\.[0-9]+){0,1} MHz \[${CHANNEL_NUM}\]")
         [[ -z "${CHANNEL_INFO}" ]] && return 1
         [[ "${CHANNEL_INFO}" == *no\ IR* ]] && return 1
         [[ "${CHANNEL_INFO}" == *disabled* ]] && return 1
         return 0
     else
         CHANNEL_NUM=$(printf '%02d' ${CHANNEL_NUM})
-        CHANNEL_INFO=$(iwlist ${IFACE} channel | grep -E "Channel[[:blank:]]${CHANNEL_NUM}[[:blank:]]?:")
+        CHANNEL_INFO=$(iwlist "${IFACE}" channel | grep -E "Channel[[:blank:]]${CHANNEL_NUM}[[:blank:]]?:")
         [[ -z "${CHANNEL_INFO}" ]] && return 1
         return 0
     fi
@@ -672,9 +703,6 @@ ieee80211_frequency_to_channel() {
     fi
 }
 
-is_5ghz_frequency() {
-    [[ $1 =~ ^(49[0-9]{2})|(5[0-9]{3})$ ]]
-}
 
 is_interface_wifi_connected() {
     if [[ $USE_IWCONFIG -eq 0 ]]; then
@@ -698,29 +726,42 @@ get_interface_mac() {
     cat "/sys/class/net/${1}/address"
 }
 
-get_interface_pci_info() {  # pci id / model / virtual
+show_interface_pci_info() {  # pci id / model / virtual
     is_interface "$1" || return
     
     local device_path
-    local pci_id
-    local pci_full
+    local bus_id=""
+    local device_type_and_bus_id="unknown"
+    local driver=""
+    local device_fullname=""
     
     device_path="$(readlink -f /sys/class/net/$1)"
     
     if [[ "$device_path" == "/sys/devices/pci"* ]]; then
-        pci_id="$(echo $device_path | sed 's/\//\n/g' | tail -n 3 |sed -n 1p)"
+        local pci_path
+
+        pci_path=$device_path/../..
+        
+        if [[ -d "$pci_path/driver" ]] ; then
+            driver=$(readlink -f "$pci_path/driver" | sed 's/\//\n/g' | tail -n 1)
+        fi
+        
+        bus_id="$(echo "$device_path" | sed 's/\//\n/g' | tail -n 3 |sed -n 1p)"
+        device_type_and_bus_id="PCI: $bus_id"
         
         if which lspci >/dev/null 2>&1 ; then
-            pci_full="$( lspci -D -nn | grep -E "^$pci_id " )"
-            echo "  PCI: $pci_full"
-        else
-            echo "  PCI: $pci_id"
+            device_fullname="$( lspci -D -nn -s "$bus_id" | awk '{$1="" ; print $0}' )"
         fi
+        
     elif [[ "$device_path" == *"/virtual/"* ]]; then
-        echo "  virtual interface"
+        device_type_and_bus_id="virtual interface"
     fi
+    
+    echo "$device_type_and_bus_id"
+    [[ -n "$driver" ]] && echo "System-already-loaded driver: $driver"
+    [[ -n "$device_fullname" ]] && echo "$device_fullname"
+    echo ""
     # TODO usb
-    # TODO current driver
 }
 
 alloc_new_vface_name() { # only for wifi
@@ -730,16 +771,16 @@ alloc_new_vface_name() { # only for wifi
         while :; do
             v_iface_name="x$i${WIFI_IFACE}"
             i=$((i + 1))
-            is_vface_name_allocated ${v_iface_name} || break
+            is_vface_name_allocated "${v_iface_name}" || break
         done
     fi
-    mkdir -p $COMMON_CONFDIR/vfaces
-    touch $COMMON_CONFDIR/vfaces/${v_iface_name}
+    mkdir -p "$COMMON_CONFDIR/vfaces"
+    touch "$COMMON_CONFDIR/vfaces/${v_iface_name}"
     echo "${v_iface_name}"
 }
 
 dealloc_vface_name() {
-    rm -f $COMMON_CONFDIR/vfaces/$1
+    rm -f "$COMMON_CONFDIR/vfaces/$1"
 }
 
 #======
@@ -772,10 +813,10 @@ generate_random_mac() {
         r5=$( printf "%02x" $(($RANDOM%256)) )
         r6=$( printf "%02x" $(($RANDOM%256)) )
         RAND_MAC="$r1:$r2:$r3:$r4:$r5:$r6"
-        ( ! ip link | grep "link" | grep $RAND_MAC > /dev/null 2>&1 ) && \
-        ( ! ip maddress | grep "link" | grep $RAND_MAC > /dev/null 2>&1 ) && \
+        ( ! ip link | grep "link" | grep "$RAND_MAC" > /dev/null 2>&1 ) && \
+        ( ! ip maddress | grep "link" | grep "$RAND_MAC" > /dev/null 2>&1 ) && \
         ( ! ip neigh | grep "lladdr $RAND_MAC" > /dev/null 2>&1 ) && \
-        ( ! get_all_mac_in_system | grep $RAND_MAC ) && \
+        ( ! get_all_mac_in_system | grep "$RAND_MAC" ) && \
         break
     done
     echo "$RAND_MAC"
@@ -815,7 +856,7 @@ generate_random_lan_ip6_prefix() {
         r5=$( printf "%x" $(($RANDOM%240+16)) )
         r6=$( printf "%x" $(($RANDOM%240+16)) )
         r7=$( printf "%x" $(($RANDOM%240+16)) )
-        is_ip6_lan_range_available $r1 $r2 $r3 $r4 $r5 $r6 $r7 && break
+        is_ip6_lan_range_available "$r1" "$r2" "$r3" "$r4" "$r5" "$r6" "$r7" && break
     done
     echo "fd$r1:$r2$r3:$r4$r5:$r6$r7::"
 }
@@ -851,7 +892,7 @@ pid_watchdog() {
         if [[ -e "/proc/$PID" ]]; then
             ST="$(cat "/proc/$PID/status" | grep "^State:" | awk '{print $2}')"
             if [[ "$ST" != 'Z' ]]; then
-                sleep $SLEEP
+                sleep "$SLEEP"
                 continue
             fi
         fi
@@ -872,35 +913,35 @@ is_nm_running() {
 }
 
 nm_knows() {
-    (nmcli dev show $1 | grep -E "^GENERAL.STATE:" >/dev/null 2>&1 ) && return 0 # nm sees
+    (nmcli dev show "$1" | grep -E "^GENERAL.STATE:" >/dev/null 2>&1 ) && return 0 # nm sees
     return 1 # nm doesn't see this interface
 }
 nm_get_manage() { # get an interface's managed state
     local s
-    s=$(nmcli dev show $1 | grep -E "^GENERAL.STATE:") || return 2 # no such interface
-    (echo $s | grep "unmanaged" >/dev/null 2>&1) && return 1 # unmanaged
+    s=$(nmcli dev show "$1" | grep -E "^GENERAL.STATE:") || return 2 # no such interface
+    (echo "$s" | grep "unmanaged" >/dev/null 2>&1) && return 1 # unmanaged
     return 0 # managed
 }
 nm_set_unmanaged() {
-    while ! nm_knows $1 ; do # wait for virtual wifi interface seen by NM
+    while ! nm_knows "$1" ; do # wait for virtual wifi interface seen by NM
         sleep 0.5
     done
-    if nm_get_manage $1 ;then
+    if nm_get_manage "$1" ;then
         echo "Set $1 unmanaged by NetworkManager"
-        nmcli dev set $1 managed no || die "Failed to set $1 unmanaged by NetworkManager"
+        nmcli dev set "$1" managed no || die "Failed to set $1 unmanaged by NetworkManager"
         NM_UNM_LIST=$1
         sleep 1
     fi
 }
 
 nm_set_managed() {
-    nmcli dev set $1 managed yes
+    nmcli dev set "$1" managed yes
     NM_UNM_LIST=
 }
 nm_restore_manage() {
     if [[ $NM_UNM_LIST ]]; then
         echo "Restore $NM_UNM_LIST managed by NetworkManager"
-        nm_set_managed $NM_UNM_LIST
+        nm_set_managed "$NM_UNM_LIST"
         sleep 0.5
     fi
 }
@@ -1168,18 +1209,18 @@ set_interface_mac() {
     INTERFACE=$1
     MAC=$2
     
-    ip link set dev ${INTERFACE} address ${MAC} 
+    ip link set dev "${INTERFACE}" address "${MAC}" 
 }
 
 backup_interface_status() {
     # virtual wifi interface will be destroyed, so no need to save status
     
     # backup interface up or down status
-    (ip link show ${SUBNET_IFACE} |grep -q "state UP") && SUBNET_IFACE_ORIGINAL_UP_STATUS=1
+    (ip link show "${SUBNET_IFACE}" |grep -q "state UP") && SUBNET_IFACE_ORIGINAL_UP_STATUS=1
     
     # save interface old mac 
     #if [[ -n "$NEW_MACADDR" ]]; then 
-        OLD_MACADDR=$(get_interface_mac $SUBNET_IFACE)
+        OLD_MACADDR=$(get_interface_mac "$SUBNET_IFACE")
         #echo "Saved ${SUBNET_IFACE} old MAC address ${OLD_MACADDR} into RAM"
     #fi
     
@@ -1196,14 +1237,14 @@ restore_interface_status() {
     
     restore_ipv6_bits
 
-    if [[ -n "$OLD_MACADDR" && "$(get_interface_mac $SUBNET_IFACE)" != "$OLD_MACADDR" ]] ; then
+    if [[ -n "$OLD_MACADDR" && "$(get_interface_mac "$SUBNET_IFACE")" != "$OLD_MACADDR" ]] ; then
         echo "Restoring ${SUBNET_IFACE} to old MAC address ${OLD_MACADDR} ..."
-        set_interface_mac ${SUBNET_IFACE} ${OLD_MACADDR} || echo "Failed restoring ${SUBNET_IFACE} to old MAC address ${OLD_MACADDR}" >&2
+        set_interface_mac "${SUBNET_IFACE}" "${OLD_MACADDR}" || echo "Failed restoring ${SUBNET_IFACE} to old MAC address ${OLD_MACADDR}" >&2
     fi
     
     nm_restore_manage
     
-    [[ $SUBNET_IFACE_ORIGINAL_UP_STATUS -eq 1 ]] && ip link set up dev ${SUBNET_IFACE} && echo "Restore ${SUBNET_IFACE} to link up"
+    [[ $SUBNET_IFACE_ORIGINAL_UP_STATUS -eq 1 ]] && ip link set up dev "${SUBNET_IFACE}" && echo "Restore ${SUBNET_IFACE} to link up"
 }
 #---------------------------------------
 
@@ -1214,11 +1255,11 @@ kill_processes() { # for this instance
         # even if the $CONFDIR is empty, the for loop will assign
         # a value in $x. so we need to check if the value is a file
         if [[ -f $x ]] &&  sleep 0.3  && [[ -f $x ]]; then
-            pid=$(cat $x)
-            pn=$( ps -p $pid -o comm= ) 
+            pid=$(cat "$x")
+            pn=$( ps -p "$pid" -o comm= ) 
             #echo "Killing $pid $pn ... "
-            pkill -P $pid
-            kill $pid 2>/dev/null && ( echo "Killed $(basename $x) $pid $pn" && rm $x ) || echo "Failed to kill $(basename $x) $pid $pn, it may have exited"
+            pkill -P "$pid"
+            kill "$pid" 2>/dev/null && ( echo "Killed $(basename "$x") $pid $pn" && rm "$x" ) || echo "Failed to kill $(basename "$x") $pid $pn, it may have exited"
         fi
     done
 }
@@ -1226,15 +1267,15 @@ kill_processes() { # for this instance
 _cleanup() {
     local x
 
-    ip addr flush ${SUBNET_IFACE}
+    ip addr flush "${SUBNET_IFACE}"
     
-    rm -rf $CONFDIR
+    rm -rf "$CONFDIR"
     
-    ip link set down dev ${SUBNET_IFACE}
+    ip link set down dev "${SUBNET_IFACE}"
     
     if [[ $VWIFI_IFACE ]]; then # the subnet interface (virtual wifi interface) will be removed
-        iw dev ${VWIFI_IFACE} del
-        dealloc_vface_name $VWIFI_IFACE
+        iw dev "${VWIFI_IFACE}" del
+        dealloc_vface_name "$VWIFI_IFACE"
     fi
     
     restore_interface_status
@@ -1243,12 +1284,12 @@ _cleanup() {
         echo "Exiting: This is the only running instance"
         # kill common processes
         for x in $COMMON_CONFDIR/*.pid; do
-            [[ -f $x ]] && kill -9 $(cat $x) && rm $x
+            [[ -f $x ]] && kill -9 $(cat "$x") && rm "$x"
         done
         
-        rm -d $COMMON_CONFDIR/vfaces
-        rm -d $COMMON_CONFDIR
-        rm -d $TMPDIR
+        rm -d "$COMMON_CONFDIR/vfaces"
+        rm -d "$COMMON_CONFDIR"
+        rm -d "$TMPDIR"
     else
         echo "Exiting: This is NOT the only running instance"
     fi
@@ -1330,7 +1371,7 @@ list_running() {
         IFACE=${IFACE%%.*}
         subn_iface=$(cat $x/subn_iface)
 
-        if [[ $IFACE == $subn_iface ]]; then
+        if [[ "$IFACE" == "$subn_iface" ]]; then
             echo $(cat $x/pid) $IFACE
         else
             echo $(cat $x/pid) $IFACE '('$(cat $x/subn_iface)')'
@@ -1367,7 +1408,7 @@ print_clients_from_leases() {  # MAC|IP|HOST|lease
     FILEC="$(cat "$LEASE_FILE" | grep -v -E "^duid\b" | sed -r '/^\s*$/d' )"
 
     # TODO: duid is somewhat related to ipv6. I don't know about it. Not sure excluding it miss some info or not
-    echo "$FILEC" | while read line
+    echo "$FILEC" | while read -r line
     do
         #echo aa$line
         LEASEstamp="$(echo "$line" | awk '{print $1}')"
@@ -1388,20 +1429,20 @@ print_interface_neighbors_via_iproute() {  # MAC|IP|_|STATUS
     
     local line
     
-    ip n | grep -E "\bdev $IFACE\b" | sed 's/ /|/g' | while read line
+    ip n | grep -E "\bdev $IFACE\b" | sed 's/ /|/g' | while read -r line
     do
         local MAC IP STATUS
         
-        IP="$(echo $line | awk -F'|' '{print $1}')"
+        IP="$(echo "$line" | awk -F'|' '{print $1}')"
         
-        if [[ "$(echo $line | awk -F'|' '{print $4}')" == "lladdr" ]]; then # has mac
+        if [[ "$(echo "$line" | awk -F'|' '{print $4}')" == "lladdr" ]]; then # has mac
             # if has mac, $4="lladdr" and $5=macaddress and $6+=status
-            MAC="$(echo $line | awk -F'|' '{print $5}')"
-            STATUS="$(echo $line | awk -F'|' '$1="";$2="";$3="";$4="";$5="";{print}' | awk '{$1=$1;print}'| sed 's/ /,/g')"
+            MAC="$(echo "$line" | awk -F'|' '{print $5}')"
+            STATUS="$(echo "$line" | awk -F'|' '$1="";$2="";$3="";$4="";$5="";{print}' | awk '{$1=$1;print}'| sed 's/ /,/g')"
         else # no mac 
             # if no mac, $4="" and $5+=status
             MAC="?"
-            STATUS="$(echo $line | awk -F'|' '$1="";$2="";$3="";$4="";{print}' | awk '{$1=$1;print}' | sed 's/ /,/g')"
+            STATUS="$(echo "$line" | awk -F'|' '$1="";$2="";$3="";$4="";{print}' | awk '{$1=$1;print}' | sed 's/ /,/g')"
         fi
         if [[ -n "$IP" && ( "$MAC" != "?" || "$STATUS" != "FAILED" ) ]]; then
             echo "$MAC|$IP|?|$STATUS"
@@ -1411,10 +1452,10 @@ print_interface_neighbors_via_iproute() {  # MAC|IP|_|STATUS
 print_interface_neighbors_via_iw() {  # MAC|_|_|signal  
     local IFACE=$1
     local MAC SIGNAL
-    iw dev $IFACE station dump | awk '($1 ~ /Station$/) {print $2}' | while read MAC
+    iw dev "$IFACE" station dump | awk '($1 ~ /Station$/) {print $2}' | while read -r MAC
     do
         if [[ -n "$MAC" ]]; then
-            SIGNAL="$(iw dev $IFACE station get $MAC | grep "signal:" | awk '{print $2}')"
+            SIGNAL="$(iw dev "$IFACE" station get "$MAC" | grep "signal:" | awk '{print $2}')"
             echo "${MAC}|?|?|${SIGNAL}_dBm"
         fi
     done
@@ -1435,7 +1476,7 @@ list_clients() { # passive mode. (use 'arp-scan' or 'netdiscover' if want active
         fi
     else # non-number given
         IFACE="$1"
-        if ( ! is_interface $IFACE ) ; then
+        if ( ! is_interface "$IFACE" ) ; then
             echo "'$IFACE' is not an interface or PID" >&2
             exit 1
         fi
@@ -1447,18 +1488,18 @@ list_clients() { # passive mode. (use 'arp-scan' or 'netdiscover' if want active
             echo "Tip: '$IFACE' is not an interface hosted by $PROGNAME" >&2
         fi
     fi
-    output="$(echo "$output" ; print_interface_neighbors_via_iw $IFACE) "
-    output="$(echo "$output" ; print_interface_neighbors_via_iproute $IFACE)"
+    output="$(echo "$output" ; print_interface_neighbors_via_iw "$IFACE") "
+    output="$(echo "$output" ; print_interface_neighbors_via_iproute "$IFACE")"
     
     output="$(echo "$output" | sort -k 1 -k 2 -t '|' | uniq | sed -r '/^\s*$/d')"
 
-    echo "$IFACE ($(get_interface_mac $IFACE)) neighbors:"
+    echo "$IFACE ($(get_interface_mac "$IFACE")) neighbors:"
     
     local fmt="%-19s%-41s%-20s%s" # string length: MAC 17, ipv4 15, ipv6 39, hostname ?
     printf "$fmt\n"  "MAC" "IP" "HOSTNAME" "INFO"
     
     local line
-    echo "$output"| while read line
+    echo "$output"| while read -r line
     do
         if [[ -n "$line" ]]; then
             echo "$line" | awk -F'|' "{printf \"$fmt\n\",\$1,\$2,\$3,\$4}"
@@ -1490,14 +1531,14 @@ send_stop() {
     local x
 
     # send stop signal to specific pid
-    if is_running_pid $1; then
-        kill -USR1 $1
+    if is_running_pid "$1"; then
+        kill -USR1 "$1"
         return
     fi
 
     # send stop signal to specific interface
     for x in $(list_running | grep -E " \(?${1}( |\)?\$)" | cut -f1 -d' '); do
-        kill -USR1 $x
+        kill -USR1 "$x"
     done
 }
 
@@ -1560,13 +1601,13 @@ daemonizing_check(){
 #============================
 check_wifi_settings() {
 
-    if ! ( which iw > /dev/null 2>&1 && iw dev $WIFI_IFACE info > /dev/null 2>&1 ); then
-        echo "WARN: Can't use 'iw' to operate interfce '$WIFI_IFACE', trying 'iwconfig' (not as good as 'iw') ..." >&2
+    if ! ( which iw > /dev/null 2>&1 && iw dev "$WIFI_IFACE" info > /dev/null 2>&1 ); then
+        echo "WARN: Can't use 'iw' to operate interfce '$WIFI_IFACE', trying 'iwconfig' (not as good as 'iw') ... (Did you spell the interface name right?)" >&2
         USE_IWCONFIG=1
     fi
     
     if [[ $USE_IWCONFIG -eq 1 ]]; then
-        if ! (which iwconfig > /dev/null 2>&1 && iwconfig $WIFI_IFACE > /dev/null 2>&1); then
+        if ! (which iwconfig > /dev/null 2>&1 && iwconfig "$WIFI_IFACE" > /dev/null 2>&1); then
             echo "ERROR: Can't use 'iwconfig' to operate interfce '$WIFI_IFACE'" >&2
             exit 1
         fi
@@ -1577,26 +1618,18 @@ check_wifi_settings() {
         exit 1
     fi
 
-    if [[ $CHANNEL == default ]]; then
-        if [[ $FREQ_BAND == 2.4 ]]; then
-            CHANNEL=1
-        else
-            CHANNEL=36
-        fi
-    fi
-
     if [[ $FREQ_BAND != 5 && $CHANNEL -gt 14 ]]; then
         echo "Channel number is greater than 14, assuming 5GHz frequency band"
         FREQ_BAND=5
     fi
 
-    if ! can_be_ap ${WIFI_IFACE}; then
+    if ! can_be_ap "${WIFI_IFACE}"; then
         echo "ERROR: Your adapter does not support AP (master) mode" >&2
         exit 1
     fi
 
-    if ! can_be_sta_and_ap ${WIFI_IFACE}; then
-        if is_interface_wifi_connected ${WIFI_IFACE}; then
+    if ! can_be_sta_and_ap "${WIFI_IFACE}"; then
+        if is_interface_wifi_connected "${WIFI_IFACE}"; then
             echo "ERROR: Your adapter can not be a station (i.e. be connected) and an AP at the same time" >&2
             exit 1
         elif [[ $NO_VIRT -eq 0 ]]; then
@@ -1607,7 +1640,7 @@ check_wifi_settings() {
 
     HOSTAPD=$(which hostapd)
 
-    if [[ $(get_adapter_kernel_module ${WIFI_IFACE}) =~ ^(8192[cd][ue]|8723a[sue])$ ]]; then
+    if [[ $(get_adapter_kernel_module "${WIFI_IFACE}") =~ ^(8192[cd][ue]|8723a[sue])$ ]]; then
         if ! strings "$HOSTAPD" | grep -m1 rtl871xdrv > /dev/null 2>&1; then
             echo "ERROR: You need to patch your hostapd with rtl871xdrv patches." >&2
             exit 1
@@ -1634,7 +1667,7 @@ check_wifi_settings() {
         exit 1
     fi
 
-    if [[ $(get_adapter_kernel_module ${WIFI_IFACE}) =~ ^rtl[0-9].*$ ]]; then
+    if [[ $(get_adapter_kernel_module "${WIFI_IFACE}") =~ ^rtl[0-9].*$ ]]; then
         if [[ $WPA_VERSION == '1' || $WPA_VERSION == '1+2' ]]; then
             echo "WARN: Realtek drivers usually have problems with WPA1, WPA2 is recommended" >&2
         fi
@@ -1649,7 +1682,7 @@ check_wifi_settings() {
         echo "WARN: option --virt-name $VIRT_NAME has ${#VIRT_NAME} characters which might be too long, consider making it shorter in case of errors" >&2
     fi
 
-    if [[ ! -z $VIRT_NAME ]] && is_vface_name_allocated $VIRT_NAME; then
+    if [[ ! -z $VIRT_NAME ]] && is_vface_name_allocated "$VIRT_NAME"; then
       echo "WARN: interface $VIRT_NAME aleady exists, this will cause an error"
     fi
 }
@@ -1660,7 +1693,7 @@ check_if_new_mac_valid() {
         exit 1
     fi
 
-    if [[ $(get_all_mac_in_system | grep -c ${NEW_MACADDR}) -ne 0 ]]; then
+    if [[ $(get_all_mac_in_system | grep -c "${NEW_MACADDR}") -ne 0 ]]; then
         echo "WARN: MAC address '${NEW_MACADDR}' already exists" >&2
     fi
 }
@@ -1698,31 +1731,32 @@ decide_ip_addresses() {
 
 prepare_wifi_interface() {
     if [[ $USE_IWCONFIG -eq 0 ]]; then
-        iw dev ${WIFI_IFACE} set power_save off
+        iw dev "${WIFI_IFACE}" set power_save off
     fi
     
     if [[ $NO_VIRT -eq 0 ]]; then
     ## Will generate virtual wifi interface
-        if is_interface_wifi_connected ${WIFI_IFACE} && [[ FORCECHANNEL -eq 0 ]]; then
-            WIFI_IFACE_FREQ=$(iw dev ${WIFI_IFACE} link | grep -i freq | awk '{print $2}')
-            WIFI_IFACE_CHANNEL=$(ieee80211_frequency_to_channel ${WIFI_IFACE_FREQ})
-            echo "${WIFI_IFACE} already in channel ${WIFI_IFACE_CHANNEL} (${WIFI_IFACE_FREQ} MHz)"
-            if is_5ghz_frequency $WIFI_IFACE_FREQ; then
-                FREQ_BAND=5
-            else
-                FREQ_BAND=2.4
-            fi
-            if [[ $WIFI_IFACE_CHANNEL -ne $CHANNEL ]]; then
-                echo "Channel fallback to ${WIFI_IFACE_CHANNEL}"
+    
+        # TODO move this to check_wifi_settings() ?
+        if is_interface_wifi_connected "${WIFI_IFACE}"; then
+            WIFI_IFACE_FREQ=$(iw dev "${WIFI_IFACE}" link | grep -i freq | awk '{print $2}' | sed 's/\.00*$//g')  # NOTE we assume integer currently, which can be right, or wrong  in the future
+            WIFI_IFACE_CHANNEL=$(ieee80211_frequency_to_channel "${WIFI_IFACE_FREQ}")
+            
+            echo "${WIFI_IFACE} already working in channel ${WIFI_IFACE_CHANNEL} (${WIFI_IFACE_FREQ} MHz)"
+            
+            if [[ $CHANNEL == default ]]; then
+                echo "Use wifi adapter current channel $WIFI_IFACE_CHANNEL as target channel"
                 CHANNEL=$WIFI_IFACE_CHANNEL
-            else
-                echo
+            fi
+            
+            if [[ $WIFI_IFACE_CHANNEL -ne $CHANNEL ]]; then
+                echo "WARN: Wifi adapter already working in channel ${WIFI_IFACE_CHANNEL}, which is different than target channel $CHANNEL" >&2
             fi
         fi
 
         echo "Creating a virtual WiFi interface... "
         VWIFI_IFACE=$(alloc_new_vface_name)
-        if iw dev ${WIFI_IFACE} interface add ${VWIFI_IFACE} type __ap; then
+        if iw dev "${WIFI_IFACE}" interface add "${VWIFI_IFACE}" type __ap; then
             # Successfully created virtual wifi interface
             # if NM running, it will give the new virtual interface a random MAC. MAC will go back after setting NM unmanaged
             sleep 2  
@@ -1742,6 +1776,15 @@ prepare_wifi_interface() {
     else # no virtual wifi interface, use wifi device interface itself
         AP_IFACE=${WIFI_IFACE}
     fi
+    
+    if [[ $CHANNEL == default ]]; then
+        echo "Channel not specified, use default"
+        if [[ $FREQ_BAND == 2.4 ]]; then
+            CHANNEL=1
+        else
+            CHANNEL=36
+        fi
+    fi
 }
 
 decide_subnet_interface() {
@@ -1758,14 +1801,14 @@ dealwith_mac() {
     if [[ -n "$NEW_MACADDR" ]] ; then  # user choose to set subnet mac 
 
         echo "Setting ${SUBNET_IFACE} new MAC address ${NEW_MACADDR} ..."
-        set_interface_mac ${SUBNET_IFACE} ${NEW_MACADDR} || die "Failed setting new MAC address"
+        set_interface_mac "${SUBNET_IFACE}" "${NEW_MACADDR}" || die "Failed setting new MAC address"
         
     elif [[ $VWIFI_IFACE ]]; then # user didn't choose to set mac, but using virtual wifi interface
 
-        VMAC=$(get_new_macaddr_according_to_existing ${WIFI_IFACE})
+        VMAC=$(get_new_macaddr_according_to_existing "${WIFI_IFACE}")
         if [[ "$VMAC" ]]; then
             echo "Assigning MAC address $VMAC to virtual interface $VWIFI_IFACE according to $WIFI_IFACE ..."
-            set_interface_mac $VWIFI_IFACE $VMAC
+            set_interface_mac "$VWIFI_IFACE" "$VMAC"
         fi
     fi
 }
@@ -1826,6 +1869,15 @@ write_hostapd_conf() {
         echo "require_vht=1" >> "$CONFDIR/hostapd.conf"
     fi
 
+    if [[ $IEEE80211AX -eq 1 ]]; then
+        echo "ieee80211ax=1" >> "$CONFDIR/hostapd.conf"
+    fi
+
+    if [[ $REQUIRE_HE -eq 1 ]]; then
+        echo "require_he=1" >> "$CONFDIR/hostapd.conf"
+    fi
+
+
     if [[ -n "$VHT_CAPAB" ]]; then
         echo "vht_capab=${VHT_CAPAB}" >> "$CONFDIR/hostapd.conf"
     fi
@@ -1848,6 +1900,24 @@ write_hostapd_conf() {
 		EOF
 	fi
 
+    if [[ $HECHANNELWIDTH -gt 0 ]]; then
+		cat <<- EOF >> "$CONFDIR/hostapd.conf"
+			he_oper_chwidth=${HECHANNELWIDTH}
+		EOF
+	fi
+
+	if [[ $HESEG0CHINDEX -gt 0 ]]; then
+		cat <<- EOF >> "$CONFDIR/hostapd.conf"
+			he_oper_centr_freq_seg0_idx=${HESEG0CHINDEX}
+		EOF
+	fi
+
+	if [[ $HESEG1CHINDEX -gt 0 ]]; then
+		cat <<- EOF >> "$CONFDIR/hostapd.conf"
+			he_oper_centr_freq_seg1_idx=${HESEG1CHINDEX}
+		EOF
+	fi
+
     if [[ $IEEE80211N -eq 1 ]] || [[ $IEEE80211AC -eq 1 ]]; then
         echo "wmm_enabled=1" >> "$CONFDIR/hostapd.conf"
     fi
@@ -1869,7 +1939,6 @@ write_hostapd_conf() {
     else
         echo "WARN: WiFi is not protected by password" >&2
     fi
-    echo "Config for current session is $CONFDIR/hostapd.conf" # Useful for sharing with other hostapd users.
     chmod 600 "$CONFDIR/hostapd.conf"
 }
 
@@ -1932,7 +2001,7 @@ write_dnsmasq_conf() {
     if [[ $DNS ]]; then
         DNS_count=$(echo "$DNS" | awk -F, '{print NF}')
         for (( i=1;i<=DNS_count;i++ )); do
-            sep_ip_port "$(echo $DNS | cut -d, -f$i)" DNS_IP DNS_PORT
+            sep_ip_port "$(echo "$DNS" | cut -d, -f$i)" DNS_IP DNS_PORT
             [[ "$DNS_PORT" ]] && DNS_PORT_D="#$DNS_PORT"
             echo "server=${DNS_IP}${DNS_PORT_D}" >> "$CONFDIR/dnsmasq.conf"
         done
@@ -1976,7 +2045,7 @@ run_wifi_ap_processes() {
     # start access point
     #echo "hostapd command-line interface: hostapd_cli -p $CONFDIR/hostapd_ctrl"
     # start hostapd (use stdbuf when available for no delayed output in programs that redirect stdout)
-    STDBUF_PATH=`which stdbuf`
+    STDBUF_PATH=$(which stdbuf)
     if [ $? -eq 0 ]; then
         STDBUF_PATH=$STDBUF_PATH" -oL"
     fi
@@ -1996,7 +2065,7 @@ run_wifi_ap_processes() {
     #    sleep 1
     #done
     #echo -n "hostapd PID: " ; cat $CONFDIR/hostapd.pid
-    pid_watchdog $HOSTAPD_PID 10 "hostapd failed" &
+    pid_watchdog "$HOSTAPD_PID" 10 "hostapd failed. (tip: try '--hostapd-debug' to get some debug info)" &
     sleep 3
 }
 
@@ -2023,15 +2092,15 @@ start_dnsmasq() {
     DNSMASQ_PID="$(cat "$CONFDIR/dnsmasq.pid" )"
     echo  "dnsmasq PID: $DNSMASQ_PID" 
     ######(wait $DNSMASQ_PID ; die "dnsmasq failed") &  # wait can't deal with non-child
-    pid_watchdog $DNSMASQ_PID 9 "dnsmasq failed" &
+    pid_watchdog "$DNSMASQ_PID" 9 "dnsmasq failed" &
     sleep 2
 }
 
 check_rfkill_unblock_wifi() {
     local PHY
     if which rfkill > /dev/null 2>&1 ; then
-        PHY=$(get_interface_phy_device ${SUBNET_IFACE})
-        [[ -n $PHY ]] && rfkill unblock $(rfkill | grep $PHY | awk '{print $1}') >/dev/null 2>&1
+        PHY=$(get_interface_phy_device "${SUBNET_IFACE}")
+        [[ -n $PHY ]] && rfkill unblock $(rfkill | grep "$PHY" | awk '{print $1}') >/dev/null 2>&1
     fi
 }
 
@@ -2078,7 +2147,8 @@ echo
 echo "PID: $$"
 
 TARGET_IFACE="$(decide_target_interface)" || exit 1 # judge wired (-i CONN_IFACE) or wireless hotspot (--ap $WIFI_IFACE)
-echo "Target interface is ${TARGET_IFACE} ($(get_interface_mac $TARGET_IFACE)) $(get_interface_pci_info $TARGET_IFACE)"
+echo "Target interface is ${TARGET_IFACE} ($(get_interface_mac "$TARGET_IFACE")) "
+show_interface_pci_info "$TARGET_IFACE"
 
 if [[ "$MAC_USE_RANDOM" -eq 1 ]] ; then
     NEW_MACADDR="$(generate_random_mac)"
@@ -2114,7 +2184,7 @@ fi
 
 # judge channel availability after changing country code
 if [[ $WIFI_IFACE ]] ; then
-    can_transmit_to_channel ${AP_IFACE} ${CHANNEL} || die "Your adapter can not transmit to channel ${CHANNEL}, frequency band ${FREQ_BAND}GHz."
+    can_transmit_to_channel "${AP_IFACE}" ${CHANNEL} || die "Your adapter can not transmit to channel ${CHANNEL}, frequency band ${FREQ_BAND}GHz."
 fi
 
 [[ $WIFI_IFACE ]] && write_hostapd_conf
@@ -2122,8 +2192,8 @@ fi
 #===================================================
 
 # set interface unmanaged by networkManager
-if [[ $NM_RUNNING -eq 1 ]] && nm_knows $TARGET_IFACE; then # if nm knows target iface, should know subnet iface too. but need to wait until nm finds subnet iface (waiting code is in nm_set_unmanaged()
-    nm_set_unmanaged ${SUBNET_IFACE} # will write NM_UNM_LIST
+if [[ $NM_RUNNING -eq 1 ]] && nm_knows "$TARGET_IFACE"; then # if nm knows target iface, should know subnet iface too. but need to wait until nm finds subnet iface (waiting code is in nm_set_unmanaged()
+    nm_set_unmanaged "${SUBNET_IFACE}" # will write NM_UNM_LIST
 fi
 
 [[ $NO_DNSMASQ -eq 0 ]] && write_dnsmasq_conf
@@ -2131,16 +2201,16 @@ fi
 
 # initialize subnet interface
 # take subnet interface down first
-ip link set down dev ${SUBNET_IFACE} || die "Failed setting ${SUBNET_IFACE} down"
+ip link set down dev "${SUBNET_IFACE}" || die "Failed setting ${SUBNET_IFACE} down"
 # flush old IPs of subnet interface
-ip addr flush ${SUBNET_IFACE} || die "Failed flush ${SUBNET_IFACE} IP"
+ip addr flush "${SUBNET_IFACE}" || die "Failed flush ${SUBNET_IFACE} IP"
 
 dealwith_mac # setting MAC should be after setting NM unmanaged
 
 [[ $WIFI_IFACE ]] && check_rfkill_unblock_wifi
 
 # bring subnet interface up
-ip link set up dev ${SUBNET_IFACE} || die "Failed bringing ${SUBNET_IFACE} up"
+ip link set up dev "${SUBNET_IFACE}" || die "Failed bringing ${SUBNET_IFACE} up"
 
 # hostapd , haveged
 [[ $WIFI_IFACE ]] && run_wifi_ap_processes
@@ -2243,6 +2313,6 @@ show_qr() {
 bash -c "while :; do sleep 8000 ; done " &
 KEEP_RUNNING_PID=$!
 echo "$KEEP_RUNNING_PID" > "$CONFDIR/keep_running.pid"
-wait $KEEP_RUNNING_PID
+wait "$KEEP_RUNNING_PID"
 
 clean_exit