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

       setgid — set-group-ID

SYNOPSIS

       #include <unistd.h>

       int setgid(gid_t gid);

DESCRIPTION

       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 unchanged.

RETURN VALUE

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

ERRORS

       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.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       Refer to the RATIONALE section in setuid().

FUTURE DIRECTIONS

       None.

SEE ALSO

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

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

COPYRIGHT

       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 .