Regular Expressions 101

Explanation

Pro

Group 1(20[0-9]{0,2})

20the literal text 20

Character Class[0-9]{0,2}

{0,2}matches between 0 and 2 characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Character Class[\-_]?

?matches at most one character from the set below:

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Group 2([01]?[0-9])

Character Class[01]?

?matches at most one character from the set below:

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[0-9]

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Character Class[\-_]?

?matches at most one character from the set below:

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Group 3([0123]?[0-9])

Character Class[0123]?

?matches at most one character from the set below:

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

3the literal 3 (51₁₀ / 63₈ / 33₁₆)

Character Class[0-9]

0-9one character from 0 (48₁₀) to 9 (57₁₀)

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.

25 tokens

(20[0-9]{0,2})[\-_]?([01]?[0-9])[\-_]?([0123]?[0-9])

New

2017-01-01
2018-05-15-project1.backup.tar
projekt2-2018-05-15.tgz.part01.enc
projekt3-20170913.tar.gz
projekt3-2017_09_13.tar.gz