writing the same result for the duplicated values of a column - bash

Question

I'm really new to bash. I have a list of domains in a .txt file (URLs.txt). I also want to have a .csv file which consists of 3 columns separated by , (myFile.csv). My code reads each line of URLs.txt (each domain), finds its IP address and then inserts them into myFile.csv (domain in the first column, its IP in the 2nd column.
Name, IP
ex1.com, 10.20.30.40
ex2.com, 20.30.40.30
ex3.com, 10.45.60.20
ex4.com, 10.20.30.40
Here is my code:
echo "Name,IP" > myFile.csv # let's overwrite, not appending
while IFS= read -r line; do
ipValue= # initialize the value
while IFS= read -r ip; do
if [[ $ip =~ ^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
ipValue+="${ip}-" # append the results with "-"
fi
done < <(dig +short "$line") # assuming the result has multi-line
ipValue=${ipValue%-} # remove trailing "-" if any
if [[ -n $ipValue ]]; then
# if the IP is not empty
echo "$line,$ipValue" >> myFile.csv
fi
done < URLs.txt
I want to add another column to myFile.csv for keeping open ports of each IP. So output would be like this:
Name, IP, Port
ex1.com, 10.20.30.40, 21/tcp
ex2.com, 20.30.40.30, 20/tcp
ex3.com, 10.45.60.20, 33/tcp
ex4.com, 10.20.30.40, 21/tcp
I want to use Nmap to do this. After I choose an IP address from the 2nd column of myFile.csv and find its open ports using Nmap, I want to write the Nmap result to the corresponding cell of the 3rd column.
Also, if there is another similar IP in the 2nd column I want to write the Nmap result for that line too. I mean I don't want to run Nmap again for the duplicated IP. For example, in my example, there are two "10.20.30.40" in the 2nd column. I want to use Nmap just once and for the 1st "10.20.30.40" (and write the result for the 2nd "10.20.30.40" as well, Nmap should not be run for the duplicated IP).
For this to happen, I changed the first line of my code to this:
echo "Name,IP,Port" > myFile.csv
and also here is the Nmap code to find the open ports:
nmap -v -Pn -p 1-100 $ipValue -oN out.txt
port=$(grep '^[0-9]' out.txt | tr '\n' '*' | sed 's/*$//')
but I don't know what to do next and how to apply these changes to my code.
I updated my code to something like this:
echo "Name,IP" > myFile.csv # let's overwrite, not appending
while IFS= read -r line; do
ipValue= # initialize the value
while IFS= read -r ip; do
if [[ $ip =~ ^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
ipValue+="${ip}-" # append the results with "-"
fi
done < <(dig +short "$line") # assuming the result has multi-line
ipValue=${ipValue%-} # remove trailing "-" if any
if [[ -n $ipValue ]]; then
# if the IP is not empty
nmap -v -Pn -p 1-100 $ipValue -oN out.txt
port=$(grep '^[0-9]' out.txt | tr '\n' '*' | sed 's/*$//')
echo "$line,$ipValue,$port" >> myFile.csv
fi
done < URLs.txt
but this way, Nmap was used for finding the open ports of the duplicated IPs too, but I didn't want this. What should I do?

Answer 1

Here's a modified version of your script that roughly does what you want:
#!/usr/bin/env bash
# cache maps from IP addresses to open ports
declare -A cache
getports() {
local ip=$1
nmap -v -Pn -p 1-100 "$ip" -oG - \
| awk -F '\t' '
/Ports:/ {
n = split($2, a, /,? /)
printf "%s", a[2]
for (i = 3; i <= n; ++i)
printf ":%s", a[i]
}
'
}
{
echo 'Name,IP,Port'
while IFS= read -r url; do
# Read filtered dig output into array
readarray -t ips < <(dig +short "$url" | grep -E '^([0-9]+\.){3}[0-9]+$')
# Build array of open ports
unset ports
for ip in "${ips[#]}"; do
ports+=("${cache["$ip"]:=$(getports "$ip")}")
done
# Output
printf '%s,%s,%s\n' \
"$url" \
"$(IFS='-'; echo "${ips[*]}")" \
"$(IFS='-'; echo "${ports[*]}")"
done < URLs.txt
} > myFile.csv
The readarray line reads the filtered output from dig into an array of IP addresses; if that array has length zero, the rest of the loop is skipped.
Then, for each elements in the ips array, we get the ports. To avoid calling nmap if we've seen the IP address before, we use the ${parameter:=word} parameter expansion: if ${cache["$ip"]} is non-empty, use it, otherwise call the getports function and store the output in the cache associative array.
getports is called for IP addresses we haven't seen before; I've used -oG ("grepable output") to make parsing easier. The awk command filters for lines containing Ports:, which look something like
Host: 52.94.225.242 () Ports: 80/open/tcp//http/// Ignored State: closed (99)
with tab separated fields. We then split the second field on the regular expression /,? / (an optional comma followed by a blank) and store all but the first field of the resulting array, colon separated.
Finally, we print the line of CSV data; if ips or ports contain more than one element, we want to join the elements with -, which is achieved by setting IFS in the command substitution and then printing the arrays with [*].
The initial echo and the loop are grouped within curly braces so output redirection has to happen just once.