When I attempt to compile the output of this trivial lex program:

# lex.l
integer   printf("found keyword INT");

using:

$ gcc lex.yy.c

I get:

Undefined symbols:
  "_yywrap", referenced from:
      _yylex in ccMsRtp7.o
      _input in ccMsRtp7.o
  "_main", referenced from:
      start in crt1.10.6.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

lex --version tells me I'm actually using 'flex 2.5.35' although ls -fla `which lex` isn't a symlink. Any ideas why the output won't compile?