pid_t tcgetpgrp(int fildes);
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.
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.
The tcgetpgrp() function shall fail if:
- The fildes argument is not a valid file descriptor.
The calling process does not have a controlling terminal, or the file
is not the controlling terminal.
The following sections are informative.
COPYRIGHTPortions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 .