LEX(1)                                                                  LEX(1)



NAME
       lex - generator of lexical analysis programs

SYNOPSIS
       lex [ -tvfn ] [ file ] ...

DESCRIPTION
       _L_e_x  generates  programs  to be used in simple lexical analyis of text.
       The input _f_i_l_e_s (standard input default) contain regular expressions to
       be  searched  for, and actions written in C to be executed when expres‐
       sions are found.

       A C source program, ’lex.yy.c’ is generated, to be compiled thus:

              cc lex.yy.c -ll

       This program, when run, copies unrecognized portions of  the  input  to
       the  output,  and  executes  the  associated  C action for each regular
       expression that is recognized.

       The options have the following meanings.

       -t     Place the result on the  standard  output  instead  of  in  file
              "lex.yy.c".

       -v     Print  a  one-line  summary  of statistics of the generated ana‐
              lyzer.

       -n     Opposite of -v; -n is default.

       -f     "Faster" compilation: don’t bother to pack the resulting tables;
              limited to small programs.

EXAMPLE
              lex lexcommands

       would  draw  _l_e_x  instructions from the file _l_e_x_c_o_m_m_a_n_d_s_, and place the
       output in _l_e_x_._y_y_._c


              %%
              [A-Z] putchar(yytext[0]+´a´-´A´);
              [ ]+$ ;
              [ ]+  putchar(´ ´);

       is an example of a _l_e_x program that would be put  into  a  _l_e_x  command
       file.  This program converts upper case to lower, removes blanks at the
       end of lines, and replaces multiple blanks by single blanks.

SEE ALSO
       yacc(1), sed(1)
       M. E. Lesk and E. Schmidt, _L_E_X _- _L_e_x_i_c_a_l _A_n_a_l_y_z_e_r _G_e_n_e_r_a_t_o_r



7th Edition                     April 14, 1986                          LEX(1)