backupfs
                   A clone of Plan9's dumpfs


                       Yoichi Hariguchi


Usage:

  1.  backupfs /full/path/of/target /full/path/of/backups

      This makes a daily snapshot of /full/path/of/target
      under /full/path/of/backups. For example, assume
      `backupfs' is executed on July 20, 2015 for the FIRST
      TIME, everything under /full/path/of/target is copied to
      the following directory:

      /full/path/of/backups/2015/07/20/full/path/of/target

      Now assume it is executed on July 23, 2015 for
      the second time (`backupfs' does not require to be
      executed everyday), everything under /full/path/of/target
      is copied to the following directory:

      /full/path/of/backups/2015/07/23/full/path/of/target

      For the second time and after, only new and changed files
      are copied. The files with no change were hard-linked to
      the same file under /full/path/of/backups. Both target
      and backup directories must be full path.

  2. backupfs host:/full/path/of/target /full/path/of/backups
     This does the same thing as '1.', but the target directory
     is located in a remote host called "host". `backupfs' uses
     ssh to copy; you need to create an ssh key pair. See below
     for more details.



How to install:

1. LOCAL AND REMOTE BACKUPS

0. Install boost C++ Libraries (http://www.boost.org/)

1. WINDOWS ONLY: install cygwin including sshd
     http://www.cygwin.com/
     http://pigtail.net/LRP/printsrv/cygwin-sshd.html
   on the windows machines which you want to run backupfs
   client. Windows machines can become *ONLY* backupfs clinets.
2. Open the backupfs source package on local host (server) and
   remote hosts
3. Run "make" on local host and remote hosts
4. Become root (Administrator on Windows) and run "make
   install" on local host and remote hosts.


2. UNIX BACKUPFS SERVER

1. Run "make ssh-keygen" to create an SSH authentication key
   pair with no passphrase.
2. Copy the secret key (id_rsa) to the backup root directory
   for a remote host as .id_rsa. If the backup root directory
   for host foo is /backup/foo, copy id_rsa as
   /backup/foo/.id_rsa. You can use the same secret key for
   multiple hosts as well as use a different key for each 
   remote host.


3. WINDOWS REMOTE BACKUPFS CLIENTS

1. Create an account "backupfs" with "Computer Administrator"
   privilege on a Windows machine
2. Run the following commands in a cygwin shell console:
     # ssh Administrator@localhost
     # mkpasswd -l > /etc/passwd
3. Change the group of all the files and directories under the
   top directory to be backed up to root. Use the following
   command if the top directory is /cygdrive/c/Documents\ and Settings/foo:
     chgrp -R root /cygdrive/c/Documents\ and Settings/foo
4. Change the access mode of all the files and directories
   under the top directory to be backed up so that backupfs can
   read. The following is example commands when the top
   directory is /cygdrive/c/Documents\ and Settings/foo:
     # find /cygdrive/c/Documents\ and Settings/foo -type d \
     -exec chmod 750 {} \;
     # find /cygdrive/c/Documents\ and Settings/foo -type f \
     -exec chmod 640 {} \;


4. REMOTE BACKUPFS CLIENTS

1. Add the matching SSH authentication public key (created in
   Section 2.1) to the $HOME/.ssh/authorized_keys file on each
   remotehost. In the above example, add the content of
   id_rsa.pub to foo:/home/backupfs/.ssh/authorized_keys.
2. Run backupfs against each remote host interactively. This is
   necessary to add SSH host keys to /root/.ssh/known_hosts.
   For example, run "backupfs foo:/etc /backup/foo" if you want
   to back up /etc on remote host foo into /backup/foo on the
   local host.
3. Once backupfs is run interactively against a remote host,
   you can use backupfs to back up the remote host's
   directories non-interactively.