Is ar rcs in GCC a valid translation of link /lib in CL?

I have this command on Windows:A.objlink /lib /out:B.lib A.obj

I want to do exactly the same but with GCC 4.8.5 in Linux

I tried withA.oar rcs B.a A.oand it is generating a static library but i´m not really sure if it is the same ´cause my A.lib and my A.a have a significant size difference.