febootstrap-install ROOT LOCALFILE TARGETPATH MODE OWNER[.GROUP]
Just copying a file in isn't usually safe, for reasons which are to do with the fakeroot(8) command.
febootstrap-install initramfs new-fstab /etc/fstab ugo=rw root.root
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.