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SETREUID(2)                 BSD System Calls Manual                SETREUID(2)

NAME
     setreuid -- set real and effective user IDs

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.

     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, the standard setuid() function is pre-ferred. preferred.
     ferred.

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.

BSD                            February 8, 2001                            BSD