Bash script find sequence numbers of ip address-CodePudding

i want to find a sequence numbers in a file(bash script),if anyone can give me a tip. I have a file with ip address

like. 172.15.0.1 172.15.0.6 172.15.0.7 172.15.0.8 172.15.0.10 172.15.0.15 172.15.0.16

And i want to find lets say the 3 first sequence numbers

like this 172.15.0.6 172.15.0.7 172.15.0.8

i tried with grep or sed or awk or loops but i couldn't find the results i want.

CodePudding user response：

Would you please try the bash script:

#!/bin/bash

report() {
    local seg=${1%.*}
    for (( i = $2 - 2; i <= $2; i   )); do
        echo "$seg.$i"
    done
}

prev=255                                # initial value as a workaround
while IFS= read -r ip; do
    n=${ip##*.}                         # extract the last octet
    if (( n == prev   1 )); then
        (( count   ))
        if (( count >= 2 )); then       # found three sequences
            report "$ip" "$n"           # then report them
        fi
    else
        count=0                         # reset the count if fail
    fi
    prev=$n
done < <(tr -s ' ' '\n' < input_file.txt | sort -t. -nk4,4)

where input_file.txt is the filename which contain the ip addresses.
Output with the provided file:

172.15.0.6
172.15.0.7
172.15.0.8

tr -s ' ' '\n' replaces the whitespaces with newline characters so the output can be fed to sort command.
sort -t. -nk4,4 sorts the input with the last octet in numerical order.
The output is fed to the while loop via the process substitution < <(commands).
Now the while loop process the input line by line (ip by ip).
The variable n is assigned to the last (4th) octet.
n is compared with the prev which holds the number in the last line. If n == prev 1 holds, the numbers are in sequence. Then count is accumulated.
If count reaches 2, the three lines including the current line are in the sequence. Then parameters are passed to the function report.

CodePudding user response：

Given a file with a range of ip addresses separated by whitespace this awk solution might be what you're looking for:

$ awk -vRS=" " '/172.15.0.[6-8]/{print}' file.txt 
172.15.0.6
172.15.0.7
172.15.0.8

The -vRS part means that the RS (record separator) variable is set to one whitespace character.

CodePudding user response：

This should give:

echo "172.15.0.1 172.15.0.6 172.15.0.7 172.15.0.8 172.15.0.10 172.15.0.15 172.15.0.16" | grep -oP $(echo 172.15.0.{6..8} | tr ' ' '|')

172.15.0.6
172.15.0.7
172.15.0.8

EDIT2:

Here's my second attempt:

j=0
i=2
myip=172.15.0
allIPs="$myip.1 $myip.2 $myip.6 $myip.7 $myip.8 $myip.10 $myip.15 $myip.16"
# while less or equal than 255
while [ $i -le 255 ] ; do
    # we will build a string that has a sequence range, for example 172.15.0.38|172.15.0.39|172.15.0.40
    ips=""
    # this builds the ip range sequence and adds it to ips
    for ip in $(seq $j $i); do ips=${ips}$(echo -n 172.15.0."$ip")"|"; done
    # we remove the last character which is '|'
    ips=${ips::-1}
    # this is the result that will match the sequence range
    res=$(echo $allIPs | grep -oP $ips)
    # if it matches, it will print it by checking that the IPs are actually found
    if [ $(echo $res | tr ' ' '\n' | wc -l) == 3 ]; then 
        echo $res
    fi
    # to next range
    j=$i
    i=$(( $i   2 ))
done
# this is for the last sequence which is 253, 254, 255
res=$(echo $allIPs | grep -oP "$myip.253|$myip.254|$myip.255")
if [ $(echo $res | tr ' ' '\n' | wc -l) == 3 ]; then echo $res; fi

should give

172.15.0.6 172.15.0.7 172.15.0.8