Why isn't the diagnostic output from ls sufficient to let you know that a file doesn't exist? If for some reason, you do need to test for a file's existence (without caring what its size is):

Code:

#!/bin/ksh
while read -r file
do	if [ -e "$file" ]
	then	printf 'file "%s" exists.\n' "$file"
		ls -lrt "$file"
	else	printf 'file "%s" does not exist.\n" "$file"
	fi
done < files.txt