This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       None.

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       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
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                       SETEGID(3POSIX)

       If  gid  is  equal  to  the  real  group  ID or the saved set-group-ID, or if the process has appropriate
       privileges, setegid() shall set the effective group ID of the calling process to gid; the real group  ID,
       saved set-group-ID, and any supplementary group IDs shall remain unchanged.

       The setegid() function shall not affect the supplementary group list in any way.

       The setegid() 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.

       Thefollowingsectionsareinformative.

       None.

       None.

       setegid — set the effective group ID

       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.

       Refer to the RATIONALE section in setuid().

       Upon  successful  completion,  0  shall  be  returned;  otherwise,  -1 shall be returned and errno set to
       indicate the error.

exec, getegid(), geteuid(), getgid(), getuid(), seteuid(), setgid(), setregid(), setreuid(), setuid()

       The Base Definitions volume of POSIX.1‐2017, <sys_types.h>, <unistd.h>

       #include <unistd.h>

       int setegid(gid_t gid);