[Bash] Append labels to file. Appends ,yes to positive and ,no to negative

append.sh

#!/bin/bash    

# Path variables
csvPath="/tmp"

echo Please, enter the initial portion of the filename you want to modify
read filename
echo The following file will be modified: 
file=$(ls -t $csvPath  | grep -v NEG | grep TEST_POS_$filename | head -1)
echo "Labelled file: ${file}"
sed "s/$/,yes/" -i $csvPath/${file} 
fileNo=$(ls -t $csvPath | grep TEST_NEG_$filename | head -1)
echo "Unlabelled file: ${fileNo}"
sed "s/$/,no/" -i $csvPath/${fileNo}