C programming in Mac. stderr and stdout redirection

The following code doesn't give me any problem in Linux. But it is not that case when I run it in Mac OS 10.8.

I am wondering if I have done something wring about redirect the stderr and stdout. Is there any specific thing I need to know when doing this in Mac?

Code:

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void

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Code:

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start_server ( ) {

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Code:

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        char cmd[ MAX_BUF ];
        memset( cmd, 0, MAX_BUF );
        sprintf( cmd, "./x11vnc -storepasswd %s ", "./output/x11vnc.passwd" );
        system(cmd);
        memset( cmd, 0, MAX_BUF );
        sprintf( cmd, "./x11vnc -rfbauth %s -display :0", "./output/x11vnc.passwd" );

/* Redirect standard output to file */

        if( stdoutfp != NULL ) {
                fclose( stdoutfp );
                stdoutfp = NULL;
        }


        freopen( OUT_X11VNCOUT, "w", stdout );

        if( stdoutfp == NULL ){
                printf("Could not redirect output for X11 VNC Server.c\n");
                return;
        }
        printf("successfuln\n");
/* Redirect standard error to file */

        if( stderrfp != NULL ) {
                fclose( stderrfp );
                stdoutfp = NULL;
        }

        stderrfp = freopen( OUT_X11VNCERR, "w", stderr );
        if( stderrfp == NULL ){
                printf("Could not redirect output for X11 VNC Server.c\n");
                return;
        }
        freopen( OUT_X11VNCERR, "w", stderr );
       
        /* Start x11vnc */
#ifdef DEBUG
        printf( "DEBUG RDP: %s \n", cmd );
#endif
        x11vncfp = popen( cmd, "w" );
} /* end of start_server() */

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