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Full Discussion: C, UNIX: How to redirect 'stdout' to a file from a C code?
Top Forums Programming C, UNIX: How to redirect 'stdout' to a file from a C code? Post 302983597 by jim mcnamara on Thursday 13th of October 2016 03:52:41 PM
Old 10-13-2016
Here is sample code using dup() and dup2()- I copied this from somewhere years ago:
Code:
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>

int main(int argc, const char *argv[])
{
    int out = open("cout.log", O_RDWR|O_CREAT|O_APPEND, 0600);
    if (-1 == out) { perror("opening cout.log"); return 255; }

    int err = open("cerr.log", O_RDWR|O_CREAT|O_APPEND, 0600);
    if (-1 == err) { perror("opening cerr.log"); return 255; }

    int save_out = dup(fileno(stdout));
    int save_err = dup(fileno(stderr));

    if (-1 == dup2(out, fileno(stdout))) { perror("cannot redirect stdout"); return 255; }
    if (-1 == dup2(err, fileno(stderr))) { perror("cannot redirect stderr"); return 255; }

    puts("doing an ls or something now");

    fflush(stdout); close(out);
    fflush(stderr); close(err);

    dup2(save_out, fileno(stdout));
    dup2(save_err, fileno(stderr));

    close(save_out);
    close(save_err);

    puts("back to normal output");

    return 0;
}

From your description it does not sound like this will help you.
These 2 Users Gave Thanks to jim mcnamara For This Post:
alex_5161 kbw
 

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LEARN ABOUT DEBIAN

ns_connredirect

Ns_ConnReturn(3aolserver)				   AOLserver Library Procedures 				 Ns_ConnReturn(3aolserver)

__________________________________________________________________________________________________________________________________________________

NAME

       Ns_ConnRedirect - Internally redirect a request to a new local url

SYNOPSIS

       #include "ns.h"

       int
       Ns_ConnRedirect(conn, url)

ARGUMENTS

       Ns_Conn	 conn	(in)	  Pointer to open connection.

       char	 *url	(in)	  Pointer to string of local url.
_________________________________________________________________

DESCRIPTION

       This  routine  can  be  used  to  internally redirect to a new, local url on the server.  The url paramter specifies a path relative to the
       server, i.e., without the leading "http://host:port" portion.  The server will reset  the  Ns_Request  structure  in  the  open	connection
       pointed	to  by conn and restart connection handling, including authorization checks.  The result is a standard AOLserver request procedure
       result code, either from an underlying call to Ns_ConnRunRequest or the result of one  of  the  authorization  response	routines  such	as
       Ns_ConnReturnForbidden.	Filter callbacks, if any, are not run again with the updated connection.

       The  Ns_ConnRedirect routine is used internally in the server to support the basic file serving code (i.e., "fastpath") to redirect to spe-
       cific files when a directory is opened and by the Ns_RegisterRedirect routine to map  standard  reponse	routines  to  user-provided  local
       url's.

EXAMPLE

       The  following  example	demonstrates redirecting to an ADP help page within a custom C-level request callback whenever a ?help=topic query
       argument is present:

		int
		MyRequest(void *arg, Ns_Conn *conn)
		{
		   Ns_Set *query = Ns_ConnGetQuery(conn);

		   /* Redirect to help.adp for /myrequest?help=topic calls. */
		   if (Ns_SetGet(query, "help")) != NULL) {
		     return Ns_ConnReturnRedirect(conn, "/help.adp");
		   }
		   ...	handle non-help requests ...
		}

SEE ALSO

       Ns_RegisterRedirct(3), Ns_ConnRunRequest(3), Ns_AuthorizeRequest(3)

KEYWORDS

       connection, redirect

AOLserver								4.0						 Ns_ConnReturn(3aolserver)
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