Regular Expressions 101

Pro

^start of line

Negative Lookahead(?!.*\[[^\]\n]*$)

.*any character (except for line terminators), repeated any number of times

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

Negated Character Class[^\]\n]*

*matches any number of characters outside the set below:

\]the literal ] (93₁₀ / 135₈ / 5D₁₆)

\na line-feed (newline) character (ASCII 10)

$end of line

Negated Character Class[^[\n]*

*matches any number of characters outside the set below:

[the literal [ (91₁₀ / 133₈ / 5B₁₆)

\na line-feed (newline) character (ASCII 10)

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

.+any character (except for line terminators), repeated at least once

$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.

26 tokens

Regular Expression

^(?!.*\[[^\]\n]*$)[^[\n]*\[.+$

New

This [should match]. This line should match

This [should match]. This line should [ match

This line shouldn't match.

This line shouldn't match. This line [shouldn't match.