Re: is there a different between write(1: %addr(data): len) and 'QtmhWrStout'

[Scott Klement <rpg400-l@xxxxxxxxxxxxxxxx>]

hi Lim,

Not in all cases.

QtmhWrStout always writes to stdout.  write(1: ....) always writes to 
descriptor 1.  But they aren't always the same thing.

If I understand correctly, the original implementation of C on OS/400 
didn't have descriptors.  So stdin, stdout, stderr were not associated 
with a particular file descriptor.

Later, when descriptor support was added, IBM had to deal with the fact 
that some people expected 0,1,2 to be mapped to stdin,stdout,stderr 
(because that's how Unix works).  So they invented an environment 
variable, QIBM_USE_DESCRIPTOR_STDIO that controls this.

Furthermore, 0,1,2 always match stdin, stdout, stderr when you are in 
QShell or PASE.  I believe they also do when you are communicating with 
the HTTP server (i.e. CGI programming)

But there are situations where they don't match, such as in the native 
ILE environment (interactive or batch job) or when spawning a child job 
manually via the spawn() API and mapping pipes to descriptors 0,1,2, or 
when starting Java directly from RPG.  In those cases, you have to set 
the QIBM_USE_DESCRIPTOR_STDIO variable...



hockchai Lim wrote:
> is it correct for me to assume that write() (using handle ID of 1) and 
> QtmhWrStout essentially does the same thing of writing the data to stdout?
>
> thanks