help.txt

. 	Matches any character
^regex 	Finds regex that must match at the beginning of the line.
regex$ 	Finds regex that must match at the end of the line.
[abc] 	Set definition, can match the letter a or b or c.
[abc][vz] 	Set definition, can match a or b or c followed by either v or z.
[^abc] 	When a caret appears as the first character inside square brackets, it negates the pattern. This can match any character except a or b or c.
[a-d1-7] 	Ranges: matches a letter between a and d and figures from 1 to 7, but not d1.
X|Z 	Finds X or Z.
XZ 	Finds X directly followed by Z.
$ 	Checks if a line end follows.
\d 	Any digit, short for [0-9]
\D 	A non-digit, short for [^0-9]
\s 	A whitespace character, short for [ \t\n\x0b\r\f]
\S 	A non-whitespace character, short for [^\s]
\w 	A word character, short for [a-zA-Z_0-9]
\W 	A non-word character [^\w]
\S+ 	Several non-whitespace characters
\b 	Matches a word boundary where a word character is [a-zA-Z0-9_]. 
* 	Occurs zero or more times, is short for {0,} 	X* finds no or several letter X,
.* 	finds any character sequence
+ 	Occurs one or more times, is short for {1,} 	X+ - Finds one or several letter X
? 	Occurs no or one times, ? is short for {0,1}. 	X? finds no or exactly one letter X
{X} 	Occurs X number of times, {} describes the order of the preceding liberal 	\d{3} searches for three digits, .{10} for any character sequence of length 10.
{X,Y} 	Occurs between X and Y times, 	\d{1,4} means \d must occur at least once and at a maximum of four.
*? 	? after a quantifier makes it a reluctant quantifier. It tries to find the smallest match.