🚀 go-pugleaf

>We are looking into moving our DEC System 5500 users to a 6610 running
>VMS 5.5 which I understand includes a POSIX kernel.  I would like to find out
>what functionality the current UNIX users are going to lose (if any) running
>under VMS 5.5 with the UNIX-like (or POSIX) shell.

Remember, Unix does not mean POSIX. There are many Unix systems that are not POSIX compliant.

The software which makes VMS POSIX compliant is a VMS layered product.  It provides 1003.* interfaces/services/utilities as an addition to VMS interfaces/services/utilities.  An application written on a VMS system where the POSIX layered product is installed can be written/ported in three ways:

  1) VMS compliant
  2) VMS and POSIX compliant
  3) POSIX compliant

The degree to which your application is POSIX compliant determines the degree of porting difficulty. 100% compliant applications will port easily.

Accordingly, your shell scripts should run fine if they are POSIX (1003.2) compliant.

>The current production application is written in C, but I'm unsure of the
>compatibility between an Ultrix system and the VMS environment. It seems
>to me that the Ultrix ".exe" executable does not run in the VMS environment.

U*ix images will not run on a VMS system. The image formats are incompatable due to fundamental differences in how images are activated. 

FWIW, 1003.1 provides the operating system services interface, 1003.2 provides a shell and utilities interface, and 1003.4 provides the realtime extentions interface. 

Your source code will port fairly easily if it is POSIX compliant.  You will have to compile and link it on a VMS system.
--
            Kent Sarff
      sarff@gsrc.enet.dec.com 
          (719) 260-2571
     Digital - Colo. Spgs., CO
Digital is blameless for my rambling