"ARP -a" Command Explanation - cmd

I have tried to execute the ARP -a command in windows. I knew that it is used for mapping IP with MAC addresses.
I know the first part there but what about the other two-block? Why is at last there 0x10 and 0x16?

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Bash script doesn't function as intented on usb connection

I have written a bash script which starts a tcpip port and connects my device to my laptop for wireless debugging. This is the script at /bin/device_added.sh:
#!/bin/bash
adb shell ip -f inet addr show 2> /tmp/scripts.log
ip=$(adb shell ip -f inet addr show | egrep -o '192.*/' | sed 's/.$//')
adb tcpip 5555
adb connect $ip:5555
echo "USB device added at $(date)" >>/tmp/scripts.log
After configuring permissions with chmod, this works flawlessly on its own. But I want this script to be triggered whenever I plug in usb. I followed this answer to try to make this work. I created a 80-test.rules file at /etc/udev/rules.d and added this:
SUBSYSTEM=="usb", ACTION=="add", ENV{DEVTYPE}=="usb_device", RUN+="/bin/device_added.sh"
and reloaded the rules file using: sudo udevadm control --reload
Whenever I plug in usb, the script gets run(the date gets logged in scripts.log) but my device doesn't get connected. What am I doing wrong? Why does the script work properly when I run it manually but not when it is triggered through udev?
Edit: On basis of #markp-fuso's and #Charles Duffy's comment, I tried logging the error to /tmp/scripts.log file. Turns out I am getting this error:
line 3: adb: command not found
Now the strange part is, I got this error earlier but I solved it by placing the shell command before the tcpip command(atleast that worked when I ran the script directly). How am I supposed to deal with this error now?
Update:
As #markp-fuso pointed out, the problem was that environment variables weren't accessible to that script. Hence I created a the adb's location as a variable in the script and then made that used that variable as throught. My script now:
#!/bin/bash
adb=/home/pranil/Android/Sdk/platform-tools/adb
$adb shell ip -f inet addr show 2> /tmp/scripts.log
ip=$($adb shell ip -f inet addr show | egrep -o '192.*/' | sed 's/.$//')
$adb tcpip 5555
$adb connect $ip:5555
echo "USB device added at $(date)" >>/tmp/scripts.log
This solved the error I was getting in logs but still the adb doesn't get connected at the required port. I have no idea where I am going wrong now. One more thing, after my script runs, the offline emulator is no longer shown as an output of abd devices command.

automated retrieval of the external ip address of all of my current connections

I am trying to make a program that automatically lists all of the connections to my computer from outside of the router. The end goal of this script is that I would like to be able to have a clean list of the external IP addresses of every server/website I am connecting to. I am also trying to use this as a way to learn more about how networks, websites, and servers work so I am sorry for any mistakes I make with terminology and general knowledge!
My tcpdump bash script:
while :
do
# get myip and assign it to a variable
myip="$(ifconfig wlp2s0 | grep -E -o -m 1 "inet................" | grep -E -o "(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)")"
# tcpdump on my ip for all packets going to or from my ip address. the ipaddress of the packets is placed in IP Address.txt
sudo tcpdump -c 1 -nn host "$myip" | grep -E -o "(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)" >> IPaddress.txt
done
I thought that tcpdump would be the tool for this however I confess that I do not know how tcpdump works. This script is a bash file that I am running through ubuntu. How would I use tcpdump to collect the IP address of every website that I am connecting to? I read the tcpdump documentation and believe it can help me achieve my goal however if there are better tools out there I would love to hear it! Currently, this code only displays internal IP addresses. ;(
I'd lean more towards using ss or netstat.
ss --all --ipv4
Would show all IPv4 connections.
The same works for IPv6 of course; and you could add one of many arguments to get more detailed information if you want, such as --processes, --extended, or --info.
There's also a few more arguments to control the output format, making it more suitable for parsing:
ss --all --ipv4 --processes --no-header --oneline
Suggest to follow ss command .
Learn about ss command here.

List all IP's using the command "ip" and not "ifconfig"

I am trying to find a command that can list all the IPs (only the ip's) using the "ip" command in ubuntu 20.04.
Ip a outputs way too much, so I tried to output only a bit of it without success using ip -c -6 -o a or ip -c -4 -o a for ipv4.
Does anyone know how to list simply all the IPs of the system using the ip command. I can't find anything except by using ifconfig, which I don't want to instal just to run this script.
Thanks for your help !
Please, try this command
hostname -I
Parse ifconfig to get only my IP address using Bash
Founded someone also replying for ip addr but I will use hostname -I as #Ivan said.

Check if arp table contains certain MAC address

I want to build a .sh script for a tomatousb router that would be launched once a minute and send requests to telegrambot api once the certain mac address is added or removed from the router's arp table.
I want to store the last state (if the mac address was found) in the env variable, but I have no clue how to check for the address.
I would normally do
if [(arp -a | grep aabbccdd)!=null] then
/usr/bin/wget https://api.telegram.org/... --no-check-certificate
but that doesn't seem to work..
arp -a | egrep -o '(\w{1,2}:){5}\w{1,2}' will return all the available MAC addresses.

OS X Bash script doesn't work but individual commands do

I'm trying to turn the instructions on this page about connecting to a Soft Ether VPN on OS X into a bash script, but I'm running into some issues.
When I run each of these commands individually at the command line, I'm able to initiate the connection to the VPN just fine and set up the routing appropriately, but when I put it into a script, it doesn't work.
Here is the script in question:
#!/bin/bash
GATEWAY=`route -n get default | grep gateway | awk '{print $2}'`
VPN_IP=130.158.6.123/32
VPN_GATEWAY=192.168.0.1
vpnclient start
vpncmd localhost /CLIENT /CMD AccountConnect HomeVPN;
ipconfig set tap0 DHCP;
ifconfig tap0 down; ifconfig tap0 up
echo "waiting for dhcp to get us an address..."
sleep 15
route delete default;
route -n add $VPN_IP $GATEWAY;
route add default $VPN_GATEWAY;
Upon testing, I have confirmed that GATEWAY gets the correct value and all the other variables are set correctly. The script seems to do everything correctly up until the part where it starts changing the routes. At first I thought it was because the interface hadn't had enough time to get an IP address, so I put a pretty long wait time in to make sure it had an IP before it started trying to change routes.
Any thoughts as to why this doesn't work when put into script form?
Just a guess: sudo doesn't work well in shell scripts as it's an interactive tool and need to prompt for a password. You might consider removing the sudo commands and running the entire script using sudo.

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