flex 2.5.35-5ubuntu1 (i386 binary) in ubuntu jaunty

 Flex is a tool for generating scanners: programs which recognized lexical
 patterns in text. It reads the given input files for a description of a
 scanner to generate. The description is in the form of pairs of regular
 expressions and C code, called rules. Flex generates as output a C source
 file, lex.yy.c, which defines a routine yylex(). This file is compiled
 and linked with the -lfl library to produce an executable. When the
 executable is run, it analyzes its input for occurrences of the regular
 expressions. Whenever it finds one, it executes the corresponding C code.
 .
 The behaviour of Flex has undergone a major change since version
 2.5.4a. Flex scanners are now reentrant, and it is now possible to
 have multiple scanners in the same program with differing sets of
 defaults, and the scanners play nicer with modern C and C++
 compilers. The Flip side is that Flex no longer conforms to the POSIX
 lex behaviour, and the scanners require conforming implementations
 when flex is used in ANSI C mode. The package flex-old provides the
 older behaviour.