added network traffic statusbar tool

.local/bin/statusbar/nettraf

@@ -0,0 +1,34 @@
+#!/bin/sh
+
+# Module showing network traffic. Shows how much data has been received (RX) or
+# transmitted (TX) since the previous time this script ran. So if run every
+# second, gives network traffic per second.
+
+case $BLOCK_BUTTON in
+	3) notify-send "🌐 Network traffic module" "🔻: Traffic received
+🔺: Traffic transmitted" ;;
+	6) "$TERMINAL" -e "$EDITOR" "$0" ;;
+esac
+
+update() {
+    sum=0
+    for arg; do
+        read -r i < "$arg"
+        sum=$(( sum + i ))
+    done
+    cache=${XDG_CACHE_HOME:-$HOME/.cache}/${1##*/}
+    [ -f "$cache" ] && read -r old < "$cache" || old=0
+    printf %d\\n "$sum" > "$cache"
+    printf %d\\n $(( sum - old ))
+}
+
+lasttime=${XDG_CACHE_HOME:-$HOME/.cache}/nettraf_time
+[ -f "$lasttime" ] && read -r previoustime < "$lasttime" || previoustime=0
+rx=$(update /sys/class/net/[ew]*/statistics/rx_bytes)
+tx=$(update /sys/class/net/[ew]*/statistics/tx_bytes)
+timedifference=$(( "$(date +'%s')" - "$previoustime" ))
+rx_avg=$(( "$rx" / "$timedifference" ))
+tx_avg=$(( "$tx" / "$timedifference" ))
+
+printf "⬇%4sB/s|⬆%4sB/s\\n" $(numfmt --to=iec $rx_avg) $(numfmt --to=iec $tx_avg)
+date +'%s' > $lasttime