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regex cheat sheet

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Paul Trowbridge 2022-10-04 10:04:56 -04:00
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[https://cheatography.com/davechild/cheat-sheets/regular-expressions/](https://cheatography.com/davechild/cheat-sheets/regular-expressions/)
```
Anchors Quantifiers Groups and Ranges
^ Start of string, or start of line in multi-line pattern * 0 or more {3} Exactly 3 . Any character except new line (\n)
\A Start of string + 1 or more {3,} 3 or more (a|b) a or b
$ End of string, or end of line in multi-line pattern ? 0 or 1 {3,5} 3, 4 or 5 (...) Group
\Z End of string Add a ? to a quantifier to make it ungreedy. (?:...) Passive (non-capturing) group
\b Word boundary [abc] Range (a or b or c)
\B Not word boundary Escape Sequences [^abc] Not (a or b or c)
\< Start of word [a-q] Lower case letter from a to q
\> End of word \ Escape following character [A-Q] Upper case letter from A to Q
\Q Begin literal sequence [0-7] Digit from 0 to 7
Character Classes \E End literal sequence \x Group/subpattern number "x"
Ranges are inclusive.
\c Control character
\s White space Pattern Modifiers
\S Not white space Common Metacharacters
\d Digit g Global match
\D Not digit ^ [ . $ i * Case-insensitive
\w Word { * ( \ m * Multiple lines
\W Not word + ) | ? s * Treat string as single line
\x Hexadecimal digit < > x * Allow comments and whitespace in pattern
\O Octal digit The escape character is usually \ e * Evaluate replacement
U * Ungreedy pattern
POSIX Special Characters * PCRE modifier
[:upper:] Upper case letters \n New line String Replacement
[:lower:] Lower case letters \r Carriage return
[:alpha:] All letters \t Tab $n nth non-passive group
[:alnum:] Digits and letters \v Vertical tab $2 "xyz" in /^(abc(xyz))$/
[:digit:] Digits \f Form feed $1 "xyz" in /^(?:abc)(xyz)$/
[:xdigit:] Hexadecimal digits \xxx Octal character xxx $` Before matched string
[:punct:] Punctuation \xhh Hex character hh $' After matched string
[:blank:] Space and tab $+ Last matched string
[:space:] Blank characters $& Entire matched string
[:cntrl:] Control characters Some regex implementations use \ instead of $.
[:graph:] Printed characters
[:print:] Printed characters and spaces
[:word:] Digits, letters and underscore
Assertions
?= Lookahead assertion
?! Negative lookahead
?<= Lookbehind assertion
?!= or ?<! Negative lookbehind
?> Once-only Subexpression
?() Condition [if then]
?()| Condition [if then else]
?# Comment
```