Regular Expressions 101

^start of line

tempthe literal text temp (case sensitive)

Non-Capturing Group(?:_(?:\d{4}_\d\d_\d\d|\d\d_?\d\d_?\d{4}))?

?repeats the group contents below at most once:

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Non-Capturing Group(?:\d{4}_\d\d_\d\d|\d\d_?\d\d_?\d{4})

1st Alternative\d{4}_\d\d_\d\d

\d{4}a Unicode decimal digit, repeated exactly 4 times

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

\da Unicode decimal digit

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

\da Unicode decimal digit

2nd Alternative\d\d_?\d\d_?\d{4}

\da Unicode decimal digit

_?optionally matches the literal _ (95₁₀ / 137₈ / 5F₁₆)

\da Unicode decimal digit

_?optionally matches the literal _ (95₁₀ / 137₈ / 5F₁₆)

\d{4}a Unicode decimal digit, repeated exactly 4 times

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

txtthe literal text txt (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

^temp(?:_(?:\d{4}_\d\d_\d\d|\d\d_?\d\d_?\d{4}))?\.txt$

temp_2023_05_22.txt
temp.txt
temp_09_05_2022.txt
temp_22092023.txt