perl.exe cannot be called by ProcessStartInfo

Question

I am trying to get the following code to work so I can call a perl script from my c# program. I am developing using visual stdio 2008 on xp service pack3.

 myProcess = new Process();
        ProcessStartInfo myProcessStartInfo = new ProcessStartInfo("perl.exe");
        myProcessStartInfo.Arguments = @"C:\Documents and Settings\test_perl.pl";
        myProcessStartInfo.UseShellExecute = false;
        myProcessStartInfo.RedirectStandardOutput = true;
        myProcessStartInfo.WindowStyle = ProcessWindowStyle.Hidden;
        myProcessStartInfo.CreateNoWindow = true;
        myProcess.StartInfo = myProcessStartInfo;

        myProcess.Start();
        string output = myProcess.StandardOutput.ReadToEnd();
        MessageBox.Show(output);
        myProcess.WaitForExit();

I verify the test_perl.pl exists and If I change the perl.exe to notepad.exe, thie above code works. But if I use perl.exe, the message box is empty.

Can't figure out why this is wrong. Please help me if you know why.

Thanks

Michael Petrotta · Accepted Answer · 2009-10-20T17:24:49.373

6

Can perl.exe handle unquoted paths containing spaces on the command line? Try quoting the path:

myProcessStartInfo.Arguments = @"""C:\Documents and Settings\test_perl.pl""";

Since command-line arguments are delimited by spaces, unless the file path is quoted, the application (perl.exe, in this case) will see three arguments:

C:\Documents
and
Settings\test_perl.pl

Perl will likely try to open the file "C:\Documents". This doesn't exist, of course. The solution is to quote file paths that contain spaces (or all file paths, to be consistent).

You mention that notepad.exe handles unquoted file paths fine. Likely, that's just notepad being smarter than the average bear, and merging its arguments for you.

And verify that a file exists at that path, of course. That's actually a slightly unusual path; normally, you'll see user files in something like C:\Documents and Settings\myusername\Documents\file.ext, or such.

edited Oct 20 '09 at 17:24

answered Oct 20 '09 at 05:21

Michael Petrotta

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I don't think there is anything wrong with the file path since if I change perl.exe to notepad.exe, it works. I also get rid of the myusername\Documents\ on purpose. – alex Oct 20 '09 at 05:24
...try it anyway. notepad != perl. – Michael Petrotta Oct 20 '09 at 05:26
Michael, you are good! Thanks! It is working now. But Why the extra "" there? – alex Oct 20 '09 at 05:38
You should change the check to this answer. – tster Oct 20 '09 at 05:41
@alex: glad it helped. Since double-quotes are used to delimit strings, you need to escape the quotes if you want to include them **inside** a string. In a standard string, you would use a backslash (\") for this. Here, you're marking the string as a verbatim string with the "@" symbol. To escape double-quotes in verbatim strings, double them (""). – Michael Petrotta Oct 20 '09 at 05:45
See http://msdn.microsoft.com/en-us/library/362314fe%28VS.71%29.aspx for more information. – Michael Petrotta Oct 20 '09 at 05:47

score 0 · Answer 2 · edited Oct 20 '09 at 17:30

0

Is perl in your %PATH%? Open a command prompt and type in "perl -v"

edited Oct 20 '09 at 17:30

Sinan Ünür

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answered Oct 20 '09 at 05:09

tster

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Yes, I can execute perl xxx.pl or xxx.txt on dos window. – alex Oct 20 '09 at 05:10
I'm confused, you marked this as correct but it seems it's still not working for you. I just tried this and it worked for me. Are you sure the perl program prints anything? Are you sure that it prints on standard out? Try it in a console program instead of a windows application. what is the content of the perl program? – tster Oct 20 '09 at 05:32

perl.exe cannot be called by ProcessStartInfo

2 Answers2