lex: command not found

Hello. I have a root-server with SuSE 8.1, Apache 1.3.27 and php 4.2.2. After downloading and unpacking, i look into INSTALL. i wrote "./configure --with-mysql --with-apxs". the result was: loading cache ./config.cache checking host system type... i686-pc-linux-gnu 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 whether gcc and cc understand -c and -o together... yes checking how to run the C preprocessor... gcc -E checking for AIX... no checking if compiler supports -R... no checking if compiler supports -Wl,-rpath,... yes checking for ranlib... ranlib checking whether ln -s works... yes 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 flex... lex checking for yywrap in -ll... no checking lex output file root... ./configure: line 2356: lex: command not found configure: error: cannot find output from lex; giving up i hope you can help me cu Andy