e-help

• [abc] A single character of a, b or c
• [a-z] A Single character in a range: a to z

• a	b Match either a or b

• Either or

• \d A digit: [0-9]
• \D Not a Digit
• \w A word character [a-zA-Z0-9]
• \W Not a word character
• \s Whitespace (space, tab, newline)
• \S Not whitespace (space, tab, newline)
• \b Word boundry
• \B Not a word boundry
• . Any single character
• a{3} Exactly 3 of a: aaa
• a{3,} 3 or more of a
• a{2,4} between 2 or 4 of a: aa, aaa, or aaaa (min , max)
• ^ The begning of a line
• $ The end of a line
• • Matches zero or more occurrences
• • Matches one or more occurrences
• ? Matches zero or one occurence
• [] Matches characters in brackets
• [^ ] Matches characters NOT in bracket
• () group