Prepare Flex to be compiled: ./configure --prefix=/usr Continue with compiling the package: make make bigcheck Install the package: make install There are packages which expect to find the lex library in the /usr/lib directory. Create a symlink to account for this: ln -s libfl.a /usr/lib/libl.a Some programs don't know about flex and try to find the lex program (flex is a (better) alternative for lex). To please those programs, create a shell script named lex which calls flex in emulation mode: cat > /usr/bin/lex << "EOF" #!/bin/sh # Begin /usr/bin/lex exec /usr/bin/flex -l "$@" # End /usr/bin/lex EOF chmod 755 /usr/bin/lex