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.
If the process has appropriate privileges, setgid() shall set the
real group ID, effective group ID, and the saved set-group-ID of the
calling process to gid.
If the process does not have appropriate privileges, but gid is equal
to the real group ID or the saved set-group-ID, setgid() shall set
the effective group ID to gid; the real group ID and saved set-group-
ID shall remain unchanged.
The setgid() function shall not affect the supplementary group list
in any way.
Any supplementary group IDs of the calling process shall remain
The setgid() function shall fail if:
EINVAL The value of the gid argument is invalid and is not supported
by the implementation.
EPERM The process does not have appropriate privileges and gid does
not match the real group ID or the saved set-group-ID.
The following sections are informative.
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 http://www.unix.org/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
IEEE/The Open Group 2013 SETGID(3P)