NAME

       setreuid - set real and effective user IDs

SYNOPSIS

       #include <unistd.h>

       int setreuid(uid_t ruid, uid_t euid);

DESCRIPTION

       The  setreuid()  function shall set the real and effective user IDs of the current process
       to the values specified by the ruid and euid  arguments.  If  ruid  or  euid  is  -1,  the
       corresponding effective or real user ID of the current process shall be left unchanged.

       A  process  with  appropriate  privileges can set either ID to any value.  An unprivileged
       process can only set the effective user ID if the euid argument is  equal  to  either  the
       real, effective, or saved user ID of the process.

       It  is unspecified whether a process without appropriate privileges is permitted to change
       the real user ID to match the  current  real,  effective,  or  saved  set-user-ID  of  the
       process.

RETURN VALUE

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

ERRORS

       The setreuid() function shall fail if:

       EINVAL The value of the ruid or euid argument is invalid or out-of-range.

       EPERM  The current process does not have appropriate privileges, and either an attempt was
              made  to change the effective user ID to a value other than the real user ID or the
              saved set-user-ID or an attempt was made to change the real user ID to a value  not
              permitted by the implementation.

       The following sections are informative.

EXAMPLES

   Setting the Effective User ID to the Real User ID
       The  following  example sets the effective user ID of the calling process to the real user
       ID, so that files created later will be owned by the current user.

              #include <unistd.h>
              #include <sys/types.h>
              ...
              setreuid(getuid(), getuid());
              ...

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       getegid() , geteuid() ,  getgid()  ,  getuid()  ,  setegid()  ,  seteuid()  ,  setgid()  ,
       setregid() , 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 .