require 'mkmf' dir_config("gdbm") if have_library("gdbm", "gdbm_open") and have_header("gdbm.h") checking_for("sizeof(DBM) is available") { if try_compile(< const int sizeof_DBM = (int)sizeof(DBM); SRC $defs << '-DDBM_SIZEOF_DBM=sizeof(DBM)' else $defs << '-DDBM_SIZEOF_DBM=0' end } create_makefile("gdbm") end