4.9. Regex Syntax Look Ahead/Behind

4.9.1. Syntax

• (?=) - Lookahead

• (?<=) - Lookbehind

• (?!foo) - Negative Lookahead

• (?<!foo) - Negative Lookbehind

• \K - Stop Look Behind

4.9.2. Example

• (?=foo) - asserts that what immediately follows the current position in the string is foo

• (?<=foo) - asserts that what immediately precedes the current position in the string is foo

• (?!foo) - Asserts that what immediately follows the current position in the string is not foo

• (?<!foo) - Asserts that what immediately precedes the current position in the string is not foo

• ^\s+sh '\K.+(?=') - if line starts with sh at any indentation, then take the content of whats inside of apostrophes

• d(?=r) - matches a d only if is followed by r, but r will not be part of the overall regex match

• (?<=r)d - matches a d only if is preceded by an r, but r will not be part of the overall regex match