setreuid(3)             (BSD Compatibility Package)             setreuid(3)


   NAME
         setreuid - set real and effective user IDs

   SYNOPSIS
         cc [ flag... ] file ... -lucb

         int setreuid(ruid, euid)
         int ruid, euid;

   DESCRIPTION
         setreuid is used to set the real and effective user IDs of the
         calling process.  setreuid is implemented via the system calls setuid
         and seteuid.  If ruid is not -1, then ruid is passed to setuid; if
         euid is not -1, then euid is passed to seteuid.

         The call to seteuid is attempted first.

         See the setuid manual page for the description of the setuid and
         seteuid system calls.

   NOTE
         This library call is slightly different from the original Berkeley
         system call. You cannot set the real uid ID without resetting the
         effective and saved uid IDs.

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

   ERRORS
         setreuid will fail and neither of the user IDs will be changed if:

         EPERM          The calling process's effective user ID is not the
                        super-user and a change other than changing the real
                        user ID to the effective user ID, or changing the
                        effective user ID to the real user ID or the saved
                        set-user ID, was specified.

   SEE ALSO
         setregid(3)

         exec(2), getuid(2), setuid(2) in the Programmer's Reference Manual.











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