Positive Lookahead(?=^.{5}$) ^start of line
.{5}any character (except for line terminators), repeated exactly 5 times
$end of line
^start of line
a*the literal a (9710 / 1418 / 6116) (case sensitive), repeated any number of times
b*the literal b (9810 / 1428 / 6216) (case sensitive), repeated any number of times
c*the literal c (9910 / 1438 / 6316) (case sensitive), repeated any number of times
d*the literal d (10010 / 1448 / 6416) (case sensitive), repeated any number of times
e*the literal e (10110 / 1458 / 6516) (case sensitive), repeated any number of times
f*the literal f (10210 / 1468 / 6616) (case sensitive), repeated any number of times
g*the literal g (10310 / 1478 / 6716) (case sensitive), repeated any number of times
h*the literal h (10410 / 1508 / 6816) (case sensitive), repeated any number of times
i*the literal i (10510 / 1518 / 6916) (case sensitive), repeated any number of times
j*the literal j (10610 / 1528 / 6A16) (case sensitive), repeated any number of times
k*the literal k (10710 / 1538 / 6B16) (case sensitive), repeated any number of times
l*the literal l (10810 / 1548 / 6C16) (case sensitive), repeated any number of times
m*the literal m (10910 / 1558 / 6D16) (case sensitive), repeated any number of times
n*the literal n (11010 / 1568 / 6E16) (case sensitive), repeated any number of times
o*the literal o (11110 / 1578 / 6F16) (case sensitive), repeated any number of times
p*the literal p (11210 / 1608 / 7016) (case sensitive), repeated any number of times
q*the literal q (11310 / 1618 / 7116) (case sensitive), repeated any number of times
r*the literal r (11410 / 1628 / 7216) (case sensitive), repeated any number of times
s*the literal s (11510 / 1638 / 7316) (case sensitive), repeated any number of times
t*the literal t (11610 / 1648 / 7416) (case sensitive), repeated any number of times
u*the literal u (11710 / 1658 / 7516) (case sensitive), repeated any number of times
v*the literal v (11810 / 1668 / 7616) (case sensitive), repeated any number of times
w*the literal w (11910 / 1678 / 7716) (case sensitive), repeated any number of times
x*the literal x (12010 / 1708 / 7816) (case sensitive), repeated any number of times
y*the literal y (12110 / 1718 / 7916) (case sensitive), repeated any number of times
z*the literal z (12210 / 1728 / 7A16) (case sensitive), repeated any number of times
$end of line
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string