Re: Reading Output from Shell Command

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance

April 8, 2005

First, I don't know anything about Perl. Second, you can definitely pass
the streamreader output to the regex function, BUT you have to make sure
that the output has come back from the program before you do so. If the
string comes from the output, say about in 1/2 hour, then you might have to
continue to test whether the output you need has come back yet. As far as a
difference in performance, my view is that with sockets you are actually
sending data through a network (even if it is just on the same machine) and
therefore negiotiating connections possibly. Therefore I think it is much
better to do it with streamreaders that don't go over a network. Even if
there is no negiotiating, your program is still having to open ports,
connect, send responses back and forth... This is just my opinion and I
like having my brain picked! :-)

Joseph MCAD




"lgbjr" <lgbjr@xxxxxxxxxxxxx> wrote in message
news:OIoKWk$OFHA.580@xxxxxxxxxxxxxxxxxxxxxxx
> Joseph,
>
> Understood. while I have your attention, I think I'll pick your brain a
> bit, if that's ok. Before I start creating test apps and possible changing
> my main app, let me tell you a bit about what the app does, and see if you
> think switching to a redirect and streamreader is the way to go.
>
> 1. There are six different PERL apps that are controlled by the VB app,
> plus some other funtionality in the VB app. And, each of the PERL apps is
> run in a seperate thread, so all apps can be run simultaneously if
> desired. Some of the PERL apps can take up to an hour to run depending on
> the amount of input data.
>
> 2. When the TCPListener receives a string, it passes it to a function that
> uses several regex expressions to determine where the string should be
> displayed in the VB form. Most of the strings are sequentially added to a
> listbox. some of the strings are used to trigger progress on a progress
> bar, and some of the strings go to different labels telling the user more
> specifically what tasks are actually being completed as the PERL app runs.
>
> 3. Occasionally, due to faulty input data, the PERL app will die, and in
> this case the last string that is passed to the Listener provides
> information regarding the error cause. In this case, the VB app terminates
> the PERL process and informs the user of the specific error. another
> complication to this part is that some of the PERL apps use OLE to write
> data to an Excel spreadsheet. If the PERL app dies, I clean up not only
> the PERL app, but the Excel process as well.
>
> So, based on this, do you think I can just pass the streamreader output to
> my regex function? Do you think that there is any speed or stability
> difference between using a socket to transfer the data rather than the
> streamreader?
>
> TIA
> Lee
>
>
>
>
> "Joseph MCAD" <anonymous@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> news:ue2SbC$OFHA.1476@xxxxxxxxxxxxxxxxxxxxxxx
>> April 7, 2005
>>
>> I think you are asking whether redirecting the output will still work
>> if you specify for the black window to not show up visible. If so, the
>> answer is yes. To not make the window show use...
>>
>> p.Startinfo.UseShellExecute = false
>> p.startinfo.createnowindow = true
>>
>> I forgot to mention to call p.WaitForExit before showing the output or
>> closing the output stream reader. So...
>>
>> p.Start
>> dim reader as streamreader = p.standardoutput
>> p.waitforexit
>> messagebox.show(reader.readtoend)
>>
>> In case you don't know you specify the parameters to the .exe using the
>> arguments property...
>>
>> p.filename = "....exe"
>> p.Arguments = "-n -r /e flags"
>>
>> Glad to hear this helped!
>>
>> Joseph MCAD
>>
>>
>>
>> "lgbjr" <lgbjr@xxxxxxxxxxxxx> wrote in message
>> news:%23tsa1Z%23OFHA.4028@xxxxxxxxxxxxxxxxxxxxxxx
>>> LOL! For the past few months, I've been developing a VB.NET app that
>>> acts as a front end to several PERL apps. I use the shell command (in a
>>> thread) to start a PERL app and in one command pass all of the command
>>> line arguments (values from Textboxes, comboboxes, etc.) to the PERL
>>> App.
>>>
>>> Then, using the sledgehammer approach, I setup a TCPListener in a thread
>>> to read the output from the perl app(Of course, I had to add the
>>> TCPClient functionality to all of my PERL apps!!)
>>>
>>> For some reason, I just never thought about simply redirecting the
>>> output of the command window itself.
>>>
>>> I'll have to make a small test app to see if redirecting the output (as
>>> you stated) works as well as the TCPListener/TCPclient setup.
>>>
>>> In some of my initial attempts at controlling the PERL app from a VB
>>> App, I noticed that SendKeys does not work if the command window is
>>> hidden. Will redirecting the output work if the command window is
>>> hidden?
>>>
>>> regards,
>>> Lee
>>>
>>> "Joseph MCAD" <anonymous@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
>>> news:%231XpvQ6OFHA.3444@xxxxxxxxxxxxxxxxxxxxxxx
>>>> April 7, 2005
>>>>
>>>> You have to set the Process.Startinfo.RedirectStandardOutput property.
>>>> You can then access the Process.StandardOutput to retrieve a
>>>> Streamreader that has the output....
>>>>
>>>> dim p as new process
>>>> p.startinfo.filename = "..."
>>>> p.startinfo.redirectstandardoutput = true
>>>> p.start
>>>> dim reader as new streamreader = p.standardoutput
>>>> messagebox.show(reader.readtoend)
>>>>
>>>> Hope this helps! :-)
>>>>
>>>> Joseph MCAD
>>>>
>>>>
>>>>
>>>> "Herfried K. Wagner [MVP]" <hirf-spam-me-here@xxxxxx> wrote in message
>>>> news:ee2lIN6OFHA.3380@xxxxxxxxxxxxxxxxxxxxxxx
>>>>> "Kevin Mansel via .NET 247" <anonymous@xxxxxxxxxxxxx> schrieb:
>>>>>>Ok, basically this is my problem. I'm building a console app to call a
>>>>>>dos program. So i'm using the Shell command to call the program, now
>>>>>>depending on what happens, I want to read the output that this program
>>>>>>returns.
>>>>>
>>>>> <URL:http://dotnet.mvps.org/dotnet/samples/misc/RedirectConsole.zip>
>>>>>
>>>>> --
>>>>> M S Herfried K. Wagner
>>>>> M V P <URL:http://dotnet.mvps.org/>
>>>>> V B <URL:http://classicvb.org/petition/>
>>>>
>>>>
>>>
>>>
>>
>>
>
>


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