[Info-vax] Looking into C-include files on VMS

[MetaEd]

On Oct 29, 9:08 am, j... at cs.tu-berlin.de (Joerg Schilling) wrote:
> >$ @gnv$gnu:[lib]gnv_setup.com
> Thank you, this command worked!
> Could you please explain what this does?

GNV_SETUP.COM is intended to be run by the user after logging in and
before using the application. It is normally run from LOGIN.COM, which
is the startup file for DCL, analogous to ~/.profile for the shell.

The "@" (at) command has a similar purpose to the "." (period) or
"$include" command in bash. It will read and execute commands from the
filename argument.

"variable := value", which has a similar purpose to "alias" and
"function" (create a verb in the command language)

"DEFINE variable value" and "ASSIGN value variable", which have a
similar purpose to "export" (name and set the value of a variable in a
table for all processes to see). In VMS these are called logical
names. GNV$GNU is one. In a file name, a logical name is replaced by
its value, typically to locate the drive and directory where a file
can be found.

So this means that logical names also have a similar purpose to
symbolic links, but they do not survive system reboots like symbolic
links. They are typically redefined at boot time in SYSTARTUP.COM,
which is loosely analogous to /etc/inittab and the files in /etc/rc*.

Best wishes,

Edward