This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       None.

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee  document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or formatting errors that appear in this page are most likely to have been introduced
       during  the  conversion  of  the  source  files  to  man  page  format.  To  report  such   errors,   see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                     TCGETPGRP(3POSIX)

       The  tcgetpgrp()  function shall return the value of the process group ID of the foreground process group
       associated with the terminal.

       If there is no foreground process group, tcgetpgrp() shall return a value greater than 1  that  does  not
       match the process group ID of any existing process group.

       The  tcgetpgrp()  function  is  allowed  from  a  process that is a member of a background process group;
       however, the information may be subsequently changed by a process  that  is  a  member  of  a  foreground
       process group.

       The tcgetpgrp() function shall fail if:

       EBADF  The fildes argument is not a valid file descriptor.

       ENOTTY The  calling  process  does  not  have  a controlling terminal, or the file is not the controlling
              terminal.

       Thefollowingsectionsareinformative.

       None.

       None.

       tcgetpgrp — get the foreground process group ID

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

       None.

       Upon  successful completion, tcgetpgrp() shall return the value of the process group ID of the foreground
       process associated with the terminal. Otherwise, -1 shall be returned  and  errno  set  to  indicate  the
       error.

setsid(), setpgid(), tcsetpgrp()

       The Base Definitions volume of POSIX.1‐2017, <sys_types.h>, <unistd.h>

       #include <unistd.h>

       pid_t tcgetpgrp(int fildes);