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SETREUID(2)                   System Calls Manual                  SETREUID(2)

     setreuid - set real and effective user ID's

     Standard C Library (libc, -lc)

     #include <unistd.h>

     setreuid(uid_t ruid, uid_t euid);

     This interface is made obsolete by the saved ID functionality in
     setuid(2) and seteuid(2).

     The real and effective user ID's of the current process are set according
     to the arguments.  If the real user ID is changed, the saved user ID is
     changed to the new value of the effective user ID.

     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 may change the effective user ID to the real user ID or the saved
     user ID; only the super-user may make other changes.

     The setreuid() function 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()
     function (see setuid(2)).

     When setting the real and effective user IDs to the same value, this
     function is equivalent to the setuid() function.  When setting only the
     effective user ID, this function is equivalent to the seteuid() function.

     Upon successful completion, a value of 0 is returned.  Otherwise, a value
     of -1 is returned and errno is set to indicate the error.

     [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.

     getuid(2), seteuid(2), setgid(2), setuid(2)

     The setreuid() function call appeared in 4.2BSD.  An incompatible version
     was implemented in 4.4BSD.  It was reimplemented in NetBSD 1.2 in a way
     compatible with 4.3BSD, SunOS and Linux, but should not be used in new

NetBSD 10.99                    January 5, 2001                   NetBSD 10.99