Permission denied question

Dear forum members,

Below is my code, but I am getting permission denied when I try to run the script. Can someone explain what I am missing. I am using Mojave and try to run script on terminal.

#!/bin/bash
read -p "amino acid: " AAA
if [ "$AAA" == "ALA" ] || [ "$AAA" == "VAL" ] || [ "$AAA" == "ARG" ] || [ "$AAA" == "ASN" ] || [ "$AAA" == "ASP" ] || 
   [ "$AAA" == "CYS" ] || [ "$AAA" == "GLY" ] || [ "$AAA" == "ILE" ] || [ "$AAA" == "LEU" ] || [ "$AAA" == "LYS" ] ||
   [ "$AAA" == "MET" ] || [ "$AAA" == "PHE" ] || [ "$AAA" == "PRO" ] || [ "$AAA" == "SER" ] || [ "$AAA" == "THR" ] || 
   [ "$AAA" == "TRP" ] || [ "$AAA" == "TYR" ] || [ "$AAA" == "HIS" ] || [ "$AAA" == "GLN" ] || [ "$AAA" == "GLU" ]
then 
	for i in HS_*.pdb.txt; do
			cat $i | grep -o -i $AAA | wc -l
    	done
elif [ "$AAA" == 0 ]
	then
		exit 1
else
	read -p "amino acid: " AAA
fi

Here's the error:

I will look forward to your responses.

Sincerely,
User

In order to help one needs to know the permissions of the directory containing your data files, the permissions of the data files and the permissions of the script itself + your ID ... Without that we cant do much...

Thanks. I figured the rest out.