Section: POSIX Programmer's Manual (3P)
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.
int setgid(gid_t gid);
If the process has appropriate privileges,
shall set the real group ID, effective group ID, and the saved
set-group-ID of the calling process to
If the process does not have appropriate privileges, but
is equal to the real group ID or the saved set-group-ID,
shall set the effective group ID to
the real group ID and saved set-group-ID shall remain unchanged.
function shall not affect the supplementary group list in any way.
Any supplementary group IDs of the calling process shall remain
Upon successful completion, 0 is returned. Otherwise, -1 shall be
set to indicate the error.
function shall fail if:
The value of the
argument is invalid and is not supported by the implementation.
The process does not have appropriate privileges and
does not match the real group ID or the saved set-group-ID.
The following sections are informative.
Refer to the RATIONALE section in
The Base Definitions volume of POSIX.1-2008,
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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
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