How do I write a script that prints every line of a file that is not contained in a another file? (Bash script)

for example, I have 2 text files :

file1 consists of:

a 
b
bb
cc

file2 consists of:

aa
bc
ab

output should be:

$p1.sh file1 file2 
bb
cc

$p1.sh file2 file1
aa
bc
ab

how would I write this bash script? I was writing something like this but it was not working:

#!/bin/bash

cat "$1" | while read m  
do
    grep -f -v "$m" "$2"
done | sort -u

any sort of guidance would be appreciated! I am a beginner programmer and have no experience in writing scripts. Thank you!

I think you need to use the commands sort and comm for this job. For example:

comm -23 <(sort -u file1.txt) <(sort -u file2.txt) > file3.txt

I will leave it to you to play with the suppression flags (-1,-2,-3) for the desired outcome. I have used -23 as an example.

Another perhaps easier method is using awk as follows:

awk 'FNR==NR{lines[$0]=1;next} !($0 in lines)' file1 file2