From: briggs@encompasserve.org
Sent: Friday, April 12, 2002 11:18 AM
To: Info-VAX@Mvb.Saic.Com
Subject: Re: Redirect SYS$OUTPUT for detached process

In article <2c0966c2.0204120637.5be57503@posting.google.com>, hchen3@uwo.ca (Sammy) writes:
...
[write timestamp to newsysoutput.log]
[create process]

>   // all qiow use IO$_WRITEVBLK|IO$M_NOW 

Why are you using IO$M_NOW?

>   sys$qiow(write "open/append sys$output newSysOutput.log" to the mailbox)
>   sys$qiow(write "open/append sys$error newSysError.err" to the mailbox)
>    
>   sys$qiow(write "write sys$output "stdout" " to the mailbox)
>   sys$qiow(write "write sys$error "stderr" " to the mailbox)

...

>   I have 3 files at the end.
> 
>   report.log -> just the regular login info and accouting stuff
> 
>   newSysOutput.log;1 -> only the time stamp is here
> 
>   newSysError.err;1 -> only the time stamp is here.

Oh yeah.  That problem.  The issue is that the $ OPEN SYS$OUTPUT 
is a NOOP.  The DCL OPEN command silently fails if the logical name
specified is already open as a process permanent file.

I gave you bad advice when I recommended that you merely OPEN SYS$OUTPUT.
You'd have to close it first.  Which is difficult to do.

Hmmm.  How do we get DCL to open SYS$OUTPUT, appending to an existing
file.  Let's play some games interactively...

First try...

$ DEFINE SYS$OUTPUT "^ & *"
%DCL-E-OPENOUT, error opening ^ & * as output
-RMS-F-SYN, file specification syntax error
$ SHOW LOG SYS$OUTPUT
   "SYS$OUTPUT" = "_ALPHA$VTA1215:" (LNM$PROCESS_TABLE)

Ok.  So you can't close SYS$OUTPUT that way.

Second try...

$ CLOSE SYS$OUTPUT
$ SHOW LOG SYS$OUTPUT
   "SYS$OUTPUT" = "_ALPHA$VTA1215:" (LNM$PROCESS_TABLE)

Nope.  You might be able to close it that way, but it automatically
re-opens.

Third try...

$ CREATE your-file.dat
time-stamp
^Z
$ OPEN Q your-file.dat
$ DEFINE SYS$OUTPUT Q
$ WRITE SYS$OUTPUT "some text"
$ DEASSIGN SYS$OUTPUT
$ CLOSE Q
$ TYPE your-file.dat
time-stamp
some text
$

*BINGO -- we have a winner*

   sys$qiow(write "open/append newsysout newSysOutput.log" to the mailbox)
   sys$qiow(write "define sys$output newsysout" to the mailbox)

	John Briggs