php and oracle

Hallo, I have problems installing php in Linux Mandrake 7.2. Php work, but I can't see the oracle funcions. I guessed I had to recompile the source. I have downloaded the latest version of php from php.net. I unzipped the file in /tmp but when I write "./configure" the program go in abend with this message: creating cache ./config.cache checking for a BSD compatible install... /usr/bin/install -c checking whether build environment is sane... yes checking whether make sets ${MAKE}... yes checking for working aclocal... missing checking for working autoconf... missing checking for working automake... missing checking for working autoheader... missing checking for working makeinfo... missing Updated php_version.h checking whether to enable maintainer-specific portions of Makefiles... no checking host system type... i586-pc-linux-gnu checking for gawk... gawk checking for bison... no checking for byacc... no configure: warning: You will need bison if you want to regenerate the PHP parsers. checking for gcc... gcc checking whether the C compiler (gcc ) works... yes checking whether the C compiler (gcc ) is a cross-compiler... no checking whether we are using GNU C... yes checking whether gcc accepts -g... yes checking how to run the C preprocessor... gcc -E checking for AIX... no checking for gcc option to accept ANSI C... none needed checking for ranlib... ranlib checking whether gcc and cc understand -c and -o together... yes checking whether ln -s works... yes checking for flex... lex checking for yywrap in -ll... no checking lex output file root... ./configure: lex: command not found configure: error: cannot find output from lex; giving up what is lex??? and where I did wrong? thank you very much. Bye Marco R.