Question

While debugging I want to display console output both on console and save a backup in file.
Windows doesn’t have tee, but you can add one. Say the folder is c:\bin\ and it works fine. And I have added it into system’s PATH.

Problem is setting “[ ]| tee[.exe] output.txt” or ” | tee[.exe] output.txt” won’t work — the output.txt is just nowhere to be found. I also tried to add the c:\bin\ path explicitly in VC Directories or environment under debugging and merge environment to be yes.

“> output.txt” works fine.

Anyone has any idea how I can resolve this? Many thanks!

Answer 1

I assume that you’re putting the | tee.exe output.txt string in the project property “Debugging | Command Argument”.

Unfortunately, that property only supports the redirection operators, not the pipe operator. If you have the | tee.exe output.txt string in the preoperty and run a program that dumps the command line arguments, you’ll see that that information is just passed on as the arguments. The “Debugging | Command Argument” doesn’t actually get processed by a full-fledged shell (such as cmd.exe) – it’s just the IDE supporting some simple redirection (actually, it seems to support more than I expected):

From http://msdn.microsoft.com/en-us/library/kcw4dzyf.aspx:

You can use the following redirection operators in this box:

    < file
        Reads stdin from file.

    > file
        Writes stdout to file.

    >> file
        Appends stdout to file.

    2> file
        Writes stderr to file.

    2>> file
        Appends stderr to file.

    2> &1
        Sends stderr (2) output to same location as stdout (1).

    1> &2
        Sends stdout (1) output to same location as stderr (2).

You can have a limited version of what you’re looking for by redirecting the program’s output to a file using >> and using a tail-f command to display whatever gets added to the file. If you do this you’ll probably want to call setvbuf( stdout, NULL, _IONBF, 0 ) first thing in main() so that I/O is unbuffered. Otherwise tail -f won’t see it until the buffer gets flushed, and I imagine that you’d like to see each output operation as it occurs.

Another option is to crank the console window’s “Screen Buffer Height” property up to a large number – one of the first things I do when I get a new Windows machine is set that value to 3000 or so – then debug the program normally and copy/paste the contents of the console window before it closes.