echo "ibase=16; obase=2; $line" | BC_LINE_LENGTH=9999 bc

awk '{ len = (8 - length % 8) % 8; printf "%.*s%sn", len, "00000000", $0}'

line=4F
python -c "print ''.join([bin(int(i, 16))[2:].zfill(4) for i in '$line'])"

'01001111'

echo "ibase=16; obase=2; $line" | BC_LINE_LENGTH=9999 bc | awk '{ printf "%08dn", $0 }'