[TUHS] SVR4 vs. Solaris 2

[Alan Coopersmith via TUHS]

On 11/11/25 18:04, segaloco via TUHS wrote:
> Pardon if this question has already been asked and answered
> before, but I find myself curious.  System V Release 4 was a
> joint effort between USL and Sun, which involved contributions
> from both parties as well as other improvements.
> 
> I often see it suggested that the first version of Solaris was
> SVR4 itself, but my question is: Was the initial stock Solaris 2
> release identical to USL SVR4, or were there still additional
> value-adds that Sun made to the inaugural release of Solaris
> beyond just the joint SVR4 trunk resulting from the project
> between the two organizations?  In other words, when one
> purchased and installed the initial release of Solaris, were they
> in essence also installing SVR4 from USL, or was there some
> appreciable difference?

I didn't join Sun until years later, but I do still have access to the
source archives for both SVR4 & Solaris 2.0 and can confirm they are
very much not the same.  (A quick recursive diff shows over 5000
source files modified, and over 6000 added in Solaris 2.0 - though
some of those may have come from other USL sources like the Documenter's
Workbench.  There were also a bunch removed, like all the 3b2 architecture
support.)

Sun additions appear to include things like the /usr/ucb commands and
libraries for SunOS 4 compatibility, the snoop command, sendmail, DNS,
NIS/NFS/RPC, nsswitch, and of course, lots of SPARC architecture support.

-- 
         -Alan Coopersmith-                 alan.coopersmith at oracle.com
          Oracle Solaris Engineering - https://blogs.oracle.com/solaris