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



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

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 vol-
       ume 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,  Copy-
       right (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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                  SETREUID(3P)