1 flex is a tool for generating scanners: programs which recognized
2 lexical patterns in text. flex reads the given input files, or its
3 standard input if no file names are given, for a description of a
4 scanner to generate. The description is in the form of pairs of
5 regular expressions and C code, called rules. flex generates as
6 output a C source file, lex.yy.c, which defines a routine yylex().
7 This file is compiled and linked with the -lfl library to produce an
8 executable. When the executable is run, it analyzes its input for
9 occurrences of the regular expressions. Whenever it finds one, it
10 executes the corresponding C code.