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SETREGID(3P)               POSIX Programmer's Manual              SETREGID(3P)

PROLOG
       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.
NAME
       setregid - set real and effective group IDs
SYNOPSIS
       #include <unistd.h>
       int setregid(gid_t rgid, gid_t egid);

DESCRIPTION
       The setregid() function shall set the real and effective group  IDs  of
       the calling process.
       If  rgid  is -1, the real group ID shall not be changed; if egid is -1,
       the effective group ID shall not be changed.
       The real and effective group IDs may be set to different values in  the
       same call.
       Only  a  process  with appropriate privileges can set the real group ID
       and the effective group ID to any valid value.
       A non-privileged process can set either the real group ID to the  saved
       set-group-ID from one of the exec family of functions, or the effective
       group ID to the saved set-group-ID or the real group ID.
       Any supplementary group IDs of the calling process remain unchanged.
RETURN VALUE
       Upon successful completion, 0 shall be returned. Otherwise, -1 shall be
       returned  and errno set to indicate the error, and neither of the group
       IDs are changed.
ERRORS
       The setregid() function shall fail if:
       EINVAL The value of the rgid or egid argument  is  invalid  or  out-of-
              range.
       EPERM  The  process  does  not have appropriate privileges and a change
              other than changing the real group ID to the saved set-group-ID,
              or  changing  the effective group ID to the real group ID or the
              saved set-group-ID, was requested.

       The following sections are informative.
EXAMPLES
       None.
APPLICATION USAGE
       If a set-group-ID process sets its effective group ID to its real group
       ID,  it  can  still  set  its effective group ID back to the saved set-
       group-ID.
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       exec(), getegid(), geteuid(), getgid(), getuid(), setegid(), seteuid(),
       setgid(),   setreuid(),   setuid(),  the  Base  Definitions  volume  of
       IEEE Std 1003.1-2001, <unistd.h>
COPYRIGHT
       Portions 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 .

IEEE/The Open Group                  2003                         SETREGID(3P)