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 (consult the correspond-
       ing 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 argu-
       ments. 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 Technol-
       ogy -- 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 .

IEEE
/The Open Group                                                    2003                                                           SETREUID(3P)