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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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nohup

NOHUP(1)                                                           User Commands                                                          NOHUP(1)

NAME

       nohup - run a command immune to hangups, with output to a non-tty

SYNOPSIS

       nohup COMMAND [ARG]...
       nohup OPTION

DESCRIPTION

       Run COMMAND, ignoring hangup signals.

       --help display this help and exit

       --version
              output version information and exit

       If  standard  input  is a terminal, redirect it from an unreadable file.  If standard output is a terminal, append output to 'nohup.out' if
       possible, '$HOME/nohup.out' otherwise.  If standard error is a terminal, redirect it to standard output.   To  save  output  to  FILE,  use
       'nohup COMMAND > FILE'.

       NOTE: your shell may have its own version of nohup, which usually supersedes the version described here.  Please refer to your shell's doc-
       umentation for details about the options it supports.

AUTHOR

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SEE ALSO

       Full documentation at: <http://www.gnu.org/software/coreutils/nohup>
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