Charlie Bullen wrote:

> I have a Mandrake 9.1 installation that I am attepmting to install PHP4 
> on. I start with the following tarball, php-4.3.4.tar.gz.Unzipping and 
> un taring go fine, but when I go to ./configure , I get an error message 
> as follows,
> checking for flex... lex
> checking for yywrap in -ll... no
> checking lex output file root... ./configure: line 2425: lex: command 
> not found
> configure: error: cannot find output from lex; giving up
> 
> I then opened up the configuration file and went to line 2425 and find 
> the following:
> 
>  # The minimal lex program is just a single line: %%.  But some broken 
> lexes
> # (Solaris, I think it was) want two %% lines, so accommodate them.
> echo '%%
> %%' | $LEX
> if test -f lex.yy.c; then
>  ac_cv_prog_lex_root=lex.yy
> elif test -f lexyy.c; then
>  ac_cv_prog_lex_root=lexyy
> else
>  { echo "configure: error: cannot find output from $LEX; giving up" 
> 1>&2; exit 1; }
> 
> My interpretation of this is that my installation doesn't have lex 
> installed. Does this make sense? If this is so, what is lex and how can 
> I get it?  Is there any other reason why this install may be failing?
> 
> Normally, if I wanted PHP to be installed, I would just either install 
> it at the time I was installing the operating system, but this time i 
> deliberatly did not install it as I am working through "Sams teach 
> yourself  PHP MySQL and Apachee in 24 hours" and the installation is 
> part of the learning process. As with all education, you never know what 
> you may have to learn in order to learn what you are trying to learn.

check your install cds for either flex or lex.

As for what it is:

flex - fast lexical analyzer generator
http://www.gnu.org/software/flex/manual/html_mono/flex.html