can you please add a synchronization feature to the GNU cp

[William Tambe]

Hi,
Can you please add a synchronization feature to the GNU cp so that files
not found in the source files/folders get removed from the destination
folder?

This is a very useful feature for backups without having to use very
expensive routines.

I know rsync provide a similar feature but it would be nice to have just 
a single option to the cp command to do the work without having to use 
another tool which has its own set of options and feature.

It would make the cp command much more complete.

To clarify what I mean, here below is a small bash script that I use to
backup my machine on an external drive. I would need such a long script
if a synchronization feature was added to the GNU cp.

#! /bin/sh

destdir='/mnt/.disk_backup'

[ $UID -eq 0 -a -d ${destdir} ] && {
        cd /
        echo 'backing up...'

        # It is awsome that cp does not abrutly failed when there is no
        # space left on the device holding ${destdir} this way we can
        # still copy file with size small enough to fit inside the backup
        # device, untill it gets really full.
        cp -axuv /{bin,boot,etc,home,lib,opt,sbin,usr,var,win} ${destdir}
        echo 'syncronizing...'
        cd ${destdir} || {
                # it very important to move to ${destdir}
                # otherwise we would be deleting all the files
                # on the system. Because find below get a list of
                # files with respect to the current working directory.
                # I almost lost all my files.
                echo "cd ${destdir} failed"
                exit 1
        }

        find . | while read file
        do
                [ -e "/${file}" -o -L "/${file}" ] || rm -vrf ${file}
        done
        echo 'done'
} || echo 'backup error'