(gawk.info)Kinds of Patterns

Kinds of Patterns
-----------------

   Here is a summary of the types of patterns supported in `awk'.

`/REGULAR EXPRESSION/'
     A regular expression as a pattern.  It matches when the text of the
     input record fits the regular expression.  (Note: Regular
     Expressions.)

`EXPRESSION'
     A single expression.  It matches when its value is non-zero (if a
     number) or non-null (if a string).  (Note: Expressions as
     Patterns.)

`PAT1, PAT2'
     A pair of patterns separated by a comma, specifying a range of
     records.  The range includes both the initial record that matches
     PAT1, and the final record that matches PAT2.  (Note: Specifying
     Record Ranges with Patterns.)

`BEGIN'
`END'
     Special patterns for you to supply start-up or clean-up actions
     for your `awk' program.  (Note: The `BEGIN' and `END' Special
     Patterns.)

`EMPTY'
     The empty pattern matches every input record.  (Note: The Empty
     Pattern.)