[SOLVED] Comparing two different arrays using shell script

Issue

How do we compare two arrays and display the result in a shell script?

Suppose we have two arrays as below:

list1=( 10 20 30 40 50 60 90 100 101 102 103 104)
list2=( 10 20 30 40 50 60 70 80 90 100 )

My requirement is to compare these two arrays in an order that it will only display the result as (101 102 103 104) from list1. It should not include the values 70 and 80 which are present in list2 but not in list1.

This does not help since it is including everything:

echo "${list1[@]}" "${list2[@]}" | tr ' ' '\n' | sort | uniq -u

I tried something like this below, but why is it not working?

list1=( 10 20 30 40 50 60 70 90 100 101 102 103 104)
list2=( 10 20 30 40 50 60 70 80 90 100 )

for (( i=0; i<${#list1[@]}; i++ )); do
for (( j=0; j<${#list2[@]}; j++ )); do
     if [[ ${list1[@]} == ${list2[@] ]]; then
         echo 0
         break
             if [[  ${#list2[@]} == ${#list1[@]-1} && ${list1[@]} != ${list2[@]} ]];then
             echo ${list3[$i]}
         fi
     fi
done
done

Solution

Could also use this kind of approach

#!/bin/ksh

list1=( 10 20 30 40 50 60 90 100 101 102 103 104 )
list2=( 10 20 30 40 50 60 70 80 90 100 )

# Creating a temp array with index being the same as the values in list1

for i in ${list1[*]}; do
        list3[$i]=$i
done

# If value of list2 can be found in list3 forget this value

for j in ${list2[*]}; do
        if [[ $j -eq ${list3[$j]} ]]; then
                unset list3[$j]
        fi
done

# Print the remaining values

print ${list3[*]}

Output is

101 102 103 104

Hope it could help

EDIT

In case of the 2 list are the same :

# Print the remaining values

if [[ ${#list3[*]} -eq 0 ]]; then
        print "No differences between the list"
else
        print ${list3[*]}
fi

Answered By - Andre Gelinas

Answer Checked By - Timothy Miller (WPSolving Admin)