Regular Expressions 101

^start of line

Non-Capturing Group(?:(?:[[:xdigit:]]{4}\.){2}[[:xdigit:]]{4}|(?:[[:xdigit:]]{2}[:-]){5}[[:xdigit:]]{2}|[[:xdigit:]]{12})

1st Alternative(?:[[:xdigit:]]{4}\.){2}[[:xdigit:]]{4}

Non-Capturing Group(?:[[:xdigit:]]{4}\.){2}

{2}repeats the group contents below exactly 2 times:

Character Class[[:xdigit:]]{4}

{4}matches exactly 4 characters from the set below:

[:xdigit:]a hexadecimal digit [A-Fa-f0-9]

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[[:xdigit:]]{4}

{4}matches exactly 4 characters from the set below:

[:xdigit:]a hexadecimal digit [A-Fa-f0-9]

2nd Alternative(?:[[:xdigit:]]{2}[:-]){5}[[:xdigit:]]{2}

Non-Capturing Group(?:[[:xdigit:]]{2}[:-]){5}

{5}repeats the group contents below exactly 5 times:

Character Class[[:xdigit:]]{2}

{2}matches exactly 2 characters from the set below:

[:xdigit:]a hexadecimal digit [A-Fa-f0-9]

Character Class[:-]

:the literal : (58₁₀ / 72₈ / 3A₁₆)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[[:xdigit:]]{2}

{2}matches exactly 2 characters from the set below:

[:xdigit:]a hexadecimal digit [A-Fa-f0-9]

3rd Alternative[[:xdigit:]]{12}

Character Class[[:xdigit:]]{12}

{12}matches exactly 12 characters from the set below:

[:xdigit:]a hexadecimal digit [A-Fa-f0-9]

$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

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

^(?:(?:[[:xdigit:]]{4}\.){2}[[:xdigit:]]{4}|(?:[[:xdigit:]]{2}[:-]){5}[[:xdigit:]]{2}|[[:xdigit:]]{12})$

Test String
New

1234567890abcd
12:34:56:78:90:12
12-34-56-78-90-12
1234.5678.9012
123456789012
12:34:56:78:90:12:34