Re: question on STRQSH and grep

[Luis Rodriguez <luisro58@xxxxxxxxx>]

Scott,

Thanks for the info. I thought that was the case because, the first time I
tried to do an INSERT to a QTEMP file I found it (as Alan did now) empty. I
checked and found two jobs running, one of them a BATCHI job, where I
supposed my QTEMP file was...

BTW, In your bio I found that you are living in Wisconsin. I live in
Caracas, Venezuela, and right now (15:20 local time) our temp is about 83~84
F *:-) . *Keep warm and drive carefully!!!

Thanks again,

Luis Rodriguez
IBM Certified Systems Expert — eServer i5 iSeries


On Fri, Dec 11, 2009 at 2:58 PM, Scott Klement
<midrange-l@xxxxxxxxxxxxxxxx>wrote:

> Hello Luis,
>
> > I believe that QSH has its own QTEMP, separate from the one your job
> uses.
> >
>
> That's more or less true.
>
> Basically, when you run grep, it's running at the same time as your job.
>  So if you're reading the output of 'grep', you're reading it real-time
> as it's happening.
>
> This is more important if you're doing something like this:
>
> QSH CMD('ls | grep blah')
>
> In this example, the output of 'ls' is being read by 'grep'.  These two
> things run simultaneously... the ls and the grep programs are running
> concurrently, which greatly improves performance not to mention memory
> usage.  (If they didn't run concurrently, the output of 'ls' would have
> to be saved into a buffer somewhere so it could be processed by grep
> separately, that buffer could potentially be hundreds of megabytes
> long...)
>
> Likewise, the output from grep is being displayed concurrently on your
> screen if you're running it interactively.  (Or if you're reading the
> output directly in a program -- though, since you're running this from
> CL, you probably aren't)
>
> To enable that concurrency, they are running in separate jobs.  the 'ls'
> is running in one job, the 'grep' in another, and your program in a 3rd
> job.  That's how QShell (and indeed, all Unix environments) work.
>
> Therefore, QTEMP and QShell don't play well together.  If you want to
> use QTEMP you have to make sure it's being used by your CL program so
> that it runs inside the same job.  If QTEMP is being used by the
> background components of QSH (in my example, the 'ls' and the 'grep', or
> in Alan's example, the 'db2' and the 'grep') they will have a separate
> QTEMP from your CL program.
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