Каталог требований LSB Core 3.1

Standard	ID	Description
SUSv3	__getpgid.01	The getpgid() function shall return the process group ID of the process whose process ID is equal to pid.
SUSv3	__getpgid.02	If pid is equal to 0, getpgid() shall return the process group ID of the calling process.
SUSv3	__getpgid.03.01	Upon successful completion, getpgid() shall return a process group ID.
SUSv3	__getpgid.03.02	Otherwise, it shall return (pid_t)-1 and set errno to indicate the error.
SUSv3	__getpgid.04	The getpgid() function shall fail if:
SUSv3	__getpgid.04.01	[EPERM] The process whose process ID is equal to pid is not in the same session as the calling process, and the implementation does not allow access to the process group ID of that process from the calling process.
SUSv3	__getpgid.04.02	[ESRCH] There is no process with a process ID equal to pid.
SUSv3	__getpgid.05	The getpgid() function may fail if:
SUSv3	__getpgid.05.01	[EINVAL] The value of the pid argument is invalid.
LSB	__getpgid.30	__getpgid() has the same specification as getpgid().

The text in the Description column of SUSv3 requirements is reproduced from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2004 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