If the calling process is not already a session leader, setpgrp() sets the process group ID of the calling process to the process ID of the calling process. If setpgrp() creates a new session, then the new session has no controlling terminal.
The setpgrp() function has no effect when the calling process is a session leader.
Upon completion, setpgrp() shall return the process group ID.
No errors are defined.
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 .