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4.3.5 The regexp statement

The regexp statement configures the flavor of regular expressions for use by subsequent match, set, and insert statements.

global: regexp flags ...

Configure the type of regular expressions.

Each flag is a word specifying some regular expression feature. It can be preceded by ‘+’ to enable this feature (this is the default), or by ‘-’ to disable it. Valid flags are:


Use POSIX Extended Regular Expression syntax when interpreting regex. This is the default.


Use basic regular expressions. Equivalent to ‘-extended’.


Do not differentiate case. Subsequent regex matches will be case insensitive.

For example, the following statement enables POSIX extended, case insensitive matching:

  regex +extended +icase