NAME

       tcgetpgrp, tcsetpgrp - get and set terminal foreground process group

SYNOPSIS

       #include <unistd.h>

       pid_t tcgetpgrp(int fd);

       int tcsetpgrp(int fd, pid_t pgrp);

DESCRIPTION

       The  function  tcgetpgrp() returns the process group ID of the foreground process group on
       the terminal associated to fd, which must be  the  controlling  terminal  of  the  calling
       process.

       The function tcsetpgrp() makes the process group with process group ID pgrp the foreground
       process group on the terminal associated to fd, which must be the controlling terminal  of
       the  calling  process, and still be associated with its session.  Moreover, pgrp must be a
       (nonempty) process group belonging to the same session as the calling process.

       If tcsetpgrp() is called by a member of a background process group in its session, and the
       calling  process  is  not  blocking  or  ignoring SIGTTOU, a SIGTTOU signal is sent to all
       members of this background process group.

RETURN VALUE

       When fd  refers  to  the  controlling  terminal  of  the  calling  process,  the  function
       tcgetpgrp()  will return the foreground process group ID of that terminal if there is one,
       and some value larger than 1 that is not presently a process group ID otherwise.  When  fd
       does  not  refer  to  the controlling terminal of the calling process, -1 is returned, and
       errno is set appropriately.

       When successful, tcsetpgrp() returns 0.  Otherwise,  it  returns  -1,  and  errno  is  set
       appropriately.

ERRORS

       EBADF  fd is not a valid file descriptor.

       EINVAL pgrp has an unsupported value.

       ENOTTY The  calling  process does not have a controlling terminal, or it has one but it is
              not described by fd, or, for tcsetpgrp(), this controlling terminal  is  no  longer
              associated with the session of the calling process.

       EPERM  pgrp  has  a  supported  value, but is not the process group ID of a process in the
              same session as the calling process.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌─────────────────────────┬───────────────┬─────────┐
       │Interface                │ Attribute     │ Value   │
       ├─────────────────────────┼───────────────┼─────────┤
       │tcgetpgrp(), tcsetpgrp() │ Thread safety │ MT-Safe │
       └─────────────────────────┴───────────────┴─────────┘

CONFORMING TO

       POSIX.1-2001, POSIX.1-2008.

NOTES

       These functions are implemented via the TIOCGPGRP and TIOCSPGRP ioctls.

   History
       The ioctls appeared in 4.2BSD.  The functions are POSIX inventions.

SEE ALSO

       setpgid(2), setsid(2), credentials(7)

COLOPHON

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