How to debug a Delphi application with redirected output

Question

I've got a console application that crashes with an I/O error 6 when the output is redirected to a file. It probably has something to do with the fact that the console application changes the text color, which doesn't make much sense in a file.

This works: c:\dir\app.exe
This crashes: c:\dir\app.exe >out.txt

When I supply >out.txt as a parameter in the IDE (run\parameters\parameters\), I just get >out.txt as a parameter.

How can I debug the application with the stdout redirected to a file instead of the console?

jachguate · Accepted Answer · 2010-11-22 20:29:42Z

12

Redirection is made by the command line interpreter, in windows it is cmd.exe

To debug the application, just launch a cmd.exe with propers arguments to launch your application and redirect the output, for example:

cmd.exe /c "yourapplication.exe >redirect.txt"

To make this happen from inside IDE in order to debug, configure cmd.exe as the host application (Run/Parameters):

Run/Parameters dialog

Put a breakpoint where you want to stop, and launch a new cmd.exe (Project/Load process) with "Run to first source" after load action:

Load process dialog

And you're done... the debugger must stop the application at your breakpoint.

edited Nov 22, 2010 at 20:29

answered Nov 22, 2010 at 18:29

jachguate

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mjn · Accepted Answer · 2010-11-22 18:28:16Z

2

You could try remote debugging:

at the beginning of the application, add a ReadLn; which gives you time to attach to the process from within Delphi
start the application from a command line (specifying the >out.txt parameter)
in Delphi, connect with the app process (Run | Attach to Process...), set a breakpoint and then switch to the application to enter a key

Hint: a debugger breakpoint can also be set in code:

asm
  int 3
end;

answered Nov 22, 2010 at 18:28

mjn

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Comments

Chris Thornton · Accepted Answer · 2010-11-22 21:22:18Z

0

Make sure it isn't failing due to directory permissions. Fully-qualify the output file path to somewhere that you're guaranteed to be able to write. Otherwise, Windows7 may be playing games with the directory. (VirtualStore stuff).

answered Nov 22, 2010 at 21:22

Chris Thornton

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