NAME

       setreuid — set real and effective user ID's

LIBRARY

       Standard C Library (libc, -lc)

SYNOPSIS

       #include <unistd.h>

       int
       setreuid(uid_t ruid, uid_t euid);

DESCRIPTION

       The  real  and  effective user IDs of the current process are set according to the arguments.  If ruid or
       euid is -1, the current uid is filled in by the system.  Unprivileged users may change the real  user  ID
       to the effective user ID and vice-versa; only the super-user may make other changes.

       If  the  real  user  ID is changed (i.e. ruid is not -1) or the effective user ID is changed to something
       other than the real user ID, then the saved user ID will be set to the effective user ID.

       The setreuid() system call has been used to swap the real and effective user IDs in set-user-ID  programs
       to  temporarily  relinquish  the  set-user-ID value.  This purpose is now better served by the use of the
       seteuid(2) system call.

       When setting the real and effective user IDs to the same value, the  standard  setuid()  system  call  is
       preferred.

RETURN VALUES

       The  setreuid()  function  returns  the value 0 if successful; otherwise the value -1 is returned and the
       global variable errno is set to indicate the error.

ERRORS

       [EPERM]            The current process is not the  super-user  and  a  change  other  than  changing  the
                          effective user-id to the real user-id was specified.

SEE ALSO

       getuid(2), issetugid(2), seteuid(2), setuid(2)

HISTORY

       The setreuid() system call appeared in 4.2BSD.

Debian                                          February 8, 2001                                     SETREUID(2)