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    SubjectRe: TIOCGDEV ioctl

    > Hi Linus, Alan,
    > some applications do need to know where the console (/dev/console)
    > actually maps to. For processes with a controlling terminal, you may see
    > it in /proc/$$/stat. However, daemons are supposed to run detached (they
    > don't want to get killed by ^C) and some processes like init or bootlogd
    > do still need to be able to find out.
    > The kernel provides this information -- sort of:
    > It contains the TIOCTTYGSTRUCT syscall which returns a struct. Of course,
    > it changes between different kernel archs and revisions, so using it is
    > an ugly hack. Grab for TIOCTTYGSTRUCT_HACK in the bootlogd.c file of the
    > sysvinit sources. Shudder!
    > Having a new ioctl, just returning the device no is a much cleaner solution,
    > IMHO. So, I created the TIOCGDEV, which Miquel suggests in his sysvinit
    > sources. It makes querying the actual console device as easy as
    > int tty; ioctl (0, TIOCGDEV, &tty);
    > Patches against 2.2.18 and 2.4.0-testX are attached.
    > Please apply.

    Based on fgconsole.c. I just threw it together in a few minutes.

    * consolewhat.c - Prints which VC /dev/console is.
    #include <sys/ioctl.h>
    #include <linux/vt.h>

    struct vt_stat vtstat;
    int fd;

    fd = open("/dev/console", O_RDONLY);

    if (fd < 0 && errno == EACCES)
    fd = open("/dev/console", O_WRONLY);
    if (fd < 0)
    return -1;

    if (ioctl(fd, VT_GETSTATE, &vtstat)) {
    perror("consolewhat: VT_GETSTATE");
    printf("%d\n", vtstat.v_active);
    return 0;

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