What would this sed command do?
sed -E 's/[a-Z]{4}/(&)/' textfile.txt
It would substitute the letter with an ampersand (&).
It would place parentheses around the first four letters of each line of textfile.txt.
It would replace all letters in the textfile.txt file with ampersand (&).
It would replace the first four letters with an ampersand (&).