How do I compare file names in two directories in shell script?

Question

Right now, this is what my code looks like:

#!/bin/bash

Dir1=$1
Dir2=$2

for file1 in $Dir1/*; do
    for file2 in $Dir2/*; do
        if [[ $file1 == $file2 ]]; then
            echo "$file1 is contained in both directories"
        fi
    done
done

I am trying to compare the file names of the two directories entered and say that the file is in both directories if the filename matches. When I try to run it though, nothing is echo-ed even though I have the same file in both directories.

Answer 1

Files that are in both Dir1 and Dir2:

find "$Dir1/" "$Dir2/" -printf '%P\n' | sort | uniq -d

Files that are in Dir1 but not in Dir2:

find "$Dir1/" "$Dir2/" "$Dir2/" -printf '%P\n' | sort | uniq -u

Files that are in Dir2 but not in Dir1:

find "$Dir1/" "$Dir1/" "$Dir2/" -printf '%P\n' | sort | uniq -u

Answer 2

If you want to know what's common to two directories then this is another way with much less coding.

#!/bin/bash

comm -12 <(ls -F $1) <(ls -F $2)

See man comm for more information about the comm utility.