What is the history of shared objects on Unix? When did they first
appear, and with what object/executable file format? The a.out ZMAGIC
format doesn't seem to support them. I don't recall if COFF does.
IRIX 4 had COFF shared libraries, barely. The OS included libc_s, libgl_s, and maybe one or two other things. They were very difficult and time-consuming to create, and if you had external dependencies then things were even worse.