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.1‐2008, <sys_types.h>, <unistd.h>

COPYRIGHT

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