Regular Expressions 101

^start of line

Character Class[a-z]+

+matches at least one character from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

Group 1(-?[a-z]){0,63}

{0,63}repeats the group contents below between 0 and 63 times:

-?optionally matches the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[a-z]

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

-?optionally matches the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[a-z]+

+matches at least one character from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

$end of line

Global pattern flags

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

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

^[a-z]+(-?[a-z]){0,63}-?[a-z]+$

New

my-valid-self-signed-cert
myvalidcert

myInvalidCert
-my-invalid-self-signed-cert
my-invalid-self-signed-cert-
my-invalid--self-singed-cert