The code below uses regex to read line by line and store the data read in three separate variables. The regular expression print data only for matching time within 8:00 to 10:00

TimeIntervalRegex.sh

#!/bin/bash

c=0

grep -E -w "8:[0-5][0-9]|9:[0-5][0-9]|10:00?" log.txt | while read ip time city ; do
    
	echo "Logged in at $time with ip $ip and city $city "
    	
	c=$(( $c + 1 ))		
	echo "Found so far: $c"

done