O_NOCTTY Forbidden to obtain terminal control Invalid?

sdwyhua

The younger brother wrote a program on LINUX, according to the book <unix advanced environment programming>,
If the session leader does not specify O_NOCTTY, the terminal device will be opened to obtain the controlling terminal;
Conversely, if specified, the controlling terminal will not be obtained.

But the program indicates that it still doesn't work or get the control terminal, because I wrote extra
Using a subroutine to open the non-session group leader can't get the control terminal. When opening tty12,
"No job control in the Shell" is displayed, indicating that the control terminal failed to obtain,
Why is O_NOCTTY not valid for the session leader?

code show as below:
#include <sys / stat.h>
#include <unistd.h>
#include <stdio.h>
#include <sys / types.h>
#include <sys / stat.h>
#include <fcntl.h>
#include <stdlib.h>
int main ()
{
    pid_t pid = fork ();
    if (pid> 0)
    exit (0);
    if (pid <0)
    printf ("first fork error\n"), exit (1);
    if (setsid () <0)
    printf ("sedsid () error\n"), exit (1);

     
    umask (022);
    close (0);
    close (1);
    close (2);
     
    int _new = open ("/ dev / tty12", O_RDWR | O_NOCTTY);

     dup2 (_new, 0); // Repoint to stdin
     dup2 (_new, 1); // Repoint to stdout
     dup2 (_new, 2); // Repoint to stderr
    execl ("/ bin / bash", "bash", (char *) 0);
    
}

hongchaoch

bash will retrieve the session terminal

Kele8

: @: lol solved?