Regular expressions

With regular expressions, you can search for text by applying patterns instead of an exact text string to search for.

Beginning of line ^ Matches a line start.
End of line $ Matches a line end.
Any character . Matches any single character.
Zero or more * Matches zero or more of the preceding expression. Example: ta* matches t, ta and taa. t(ab)* matches t, tab and tabab.
One or more + Matches one or more of the preceding expression. Example: ta+ matches ta, taa and taaa.
Set of characters [] Matches any of the characters within the brackets. Example: t[ab] matches ta and tb.
Not in set [^] Matches any characters not within the brackets (following the '^'. Example: t[^ab] matches tc and td, but not ta or tb.
Or | Matches the expression before or after the '|'. Example (ta)|(tb) matches ta or tb, but not tc.
Grouping () Groups a subexpression.
Nth subexpression \N Each group ('(expression)') gets an order number from 1 to 9. 0 is the whole expression. When replacing, the text matching the Nth expression from the found text is inserted. Example: t(a)|(b) should be replaced with u\1. In the text "ta", the replacement will result in "ua", and in the text "tb" the replacement will result in "ub".
Character code \nnn or \xnn Inserts or searches for the decimal character code nnn or the hexadecimla character code xnn.
Alphabetic string :a Equivalent to [a-zA-Z].
Uppercase alphabetic string :u Equivalent to [A-Z].
Lowercase alphabetic string :l Equivalent to [a-z].
Numeric string :n Equivalent to [0-9].
Alphanumeric string :m Equivalent to [a-zA-Z0-9].
Space character :s Equivalent to [\032\009].