gem install -l redis-3.3.3.gem    

ERROR:  Loading command: install (LoadError)

        cannot load such file -- zlib

ERROR:  While executing gem ... (NoMethodError)

    undefined method `invoke_with_build_args' for nil:NilClass

1、cd ruby-2.5.1/ext/zlib目录，执行 

ruby ./extconf.rb

make 

make install

2、make时报错（chmod +x Makefile）:make: *** No rule to make target `/include/ruby.h', needed by `zlib.o'.  Stop.

3、更改Makefile文件， zlib.o: $(top_srcdir)/include/ruby.h  改成   zlib.o: ../../include/ruby.h；到这里就可以make成功了。

4、进入/ruby-2.5.1/ext/openssl目录执行 ruby ./extconf.rb、make 、make install命令。