The Question is:
The DCL RUN (detached) PROCESS command does not support passing arguments to
main( argc, argv). Neither does SYS$CREPRC(). How can I pass args to main() of
a detached process without using SUBMIT? How does SUBMIT do it?
Thank you very much.
The Answer is :
SUBMIT does not pass arguments to an image running a detached process,
rather it passes arguments to the CLI of a detached process. See F$GETQUI
function "DISPLAY_ENTRY" item codes "PARAMETER_1" through
This mechanism is completely different from the C language specific
argc/argv mechanism, though argc/argv also depends on the CLI to
communicate the arguments to the running program.
The command "RUN/DETACHED image" creates a process running the
specified image WITHOUT a CLI. This means there are a number of
features which cannot be used within this image. For example,
LIB$SPAWN, LIB$SET_LOGICAL and argc/argv among others.
It is not necessary to use SUBMIT to pass arguments to a detached
process, but it IS necessary to have a process running under a CLI. This
can be achieved by specifying the image SYS$SYSTEM:LOGINOUT.EXE to the
RUN command and feeding it DCL commands through SYS$INPUT. For example
$ myprog="$device:[directory]myprog.exe" ! Define foreign command
$ myprog arg1 arg2 arg3 ! invoke the image with args
Command to start the detached process
$ RUN/DETACHED/INPUT=device:[directory]DETACH.COM SYS$SYSTEM:LOGINOUT.EXE
Depending on the exact needs, you may find it necessary to dynamically
generate the input command procedure to change argument values. Or
you could pass the commands and the parameters to the created process
via an input mailbox, reading output data back via another mailbox.
You may also be able to use DECnet task-to-task (client-server network
communications), or a webserver CGI script or other similar approach.
Or a file.
Within DCL, examples of client-server network communcations are
available in the OpenVMS documentation set and within the Digital
Press Writing Real Programs in DCL book. Network communications
are covered in the DECnet documentation as well as the TCP/IP
Existing discussions of the f$getqui lexical include the following
topics: (813), (1240), (2159), (3951), (4546), (4568), (4903), (5188)
(5471), (5567), (5651), (5793), (5982), (6315), (6877), etc.