problem running a C program in the cygwin shell in Win XP

This is a discussion on problem running a C program in the cygwin shell in Win XP within the C Programming forums, part of the General Programming Boards category; Hi, I just installed cygwin on Windows XP. I used Visual Studio to compile a test C program. If I ...

  1. #1
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    problem running a C program in the cygwin shell in Win XP

    Hi,

    I just installed cygwin on Windows XP. I used Visual Studio to compile a test
    C program. If I were at the shell in cygwin, and typed this command:

    $ date > tmp_file

    The content of the file tmp_file in that directory would look something like this:

    Mon Jul 27 01:22:25 PDT 2009

    So when I compiled my program that looks something like below, and ran the .exe file at the prompt at the cygwin shell, the "date" command executes, the "tmp_file" got created with the correct info, but the C program hangs. I have to press <RETURN> for the program to end.

    What causes this, and how do I fix this problem? Thanks.

    Here's the samle of that command in the C function:

    system ("date > tmp_file");

  2. #2
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    It looks like it's not the UNIX commands that are causing the problem.

    If I type the Windows commands, I still have the same problem.

    I think that my syntax for the system command is not correct.

  3. #3
    Registered User slingerland3g's Avatar
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    Well with gcc alone, this works on my WinXP with Cygwin. By any chance are you calling getchar() at all?

    In Netbeans, I get what you get, without that, then I have to hit return to exit. My date_file is created as expected.

  4. #4
    and the hat of wrongness Salem's Avatar
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    date is both a cygwin command and a DOS command.

    The cygwin one just prints the date.
    The DOS one prints the current date, and prompts you for a new date. Pressing return just accepts the old date.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  5. #5
    Registered User slingerland3g's Avatar
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    Then running this within a cygwin shell you should be fine.

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    OK, I just changed it to something else, like:

    system ("ls -l > tmp_file");



    The same problem occurred. The compiled program hangs when it reaches this command. To make it continue, I have to press <RETURN>. It looks like the system command is waiting for a key to be pressed by the user, before it can continue in the C program.

    What do I need to do in my C program, so that it thinks that a <RETURN> was pressed, so that it can continue?

  7. #7
    Registered User slingerland3g's Avatar
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    I believe your <RETURN> is to exit out of your IDE, if that is the environment you ran your program in. Do you get this same behaviour when you execute your .exe from the command line?

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