Poor Man's TimeMachine: rsync

The shell script on the computer being backed up, needs a no-password ssh key to work.

#!/bin/bash

BACKUP_HOST=user@host
SSH_KEY=/home/user/.ssh/host_rsa

LOG_DIR=~/logs
LOG_FILE=$LOG_DIR/backup.`date +%Y%m%d_%H%M`.log

SRC_DIR=/home/user/
DEST_BASE_DIR=/home/user/backups/localhost
DEST_DIR_NAME=backup_`date +%Y.%m.%d_%H.%M.%S`
PREV_DIR_NAME=previous

DEST_DIR=$DEST_BASE_DIR/$DEST_DIR_NAME
PREV_DIR=$DEST_BASE_DIR/$PREV_DIR_NAME

mkdir -p $LOG_DIR

nice -10 /usr/bin/rsync --rsh="ssh -i $SSH_KEY" \
 --checksum --archive --compress --human-readable --progress --recursive \
 --link-dest=$PREV_DIR \
 --filter='merge /home/user/backup/backup.filterrules' $SRC_DIR \
 $BACKUP_HOST:$DEST_DIR >> $LOG_FILE 2>&1

ssh -i $SSH_KEY $BACKUP_HOST "link $PREV_DIR $DEST_DIR" >> $LOG_FILE 2>&1

bzip2 $LOG_FILE

A Ruby script that I use with the password-less ssh key on the server side to reduce chances of it being abused. Just add command="~/bin/backup-wrapper.rb" before your key in .ssh/authorized_keys
<br />#!/usr/bin/ruby<br /><br />SSH_ORIGINAL_COMMAND = ENV['SSH_ORIGINAL_COMMAND']<br />if SSH_ORIGINAL_COMMAND.nil?<br /> $stderr.puts "Environment variable SSH_ORIGINAL_COMMAND must be set"<br /> exit<br />end<br /><br /># Check if the command is the rsync server<br />rsyncCommand, prev_dir, dest_dir = /^rsync --server -[^ ;]+ --link-dest ([^ ;]+) \. ([^ ;]+)$/.match(SSH_ORIGINAL_COMMAND).to_a<br /><br />if !rsyncCommand.nil?<br /> dest_dir_base_idx = dest_dir.rindex('/')<br /> dest_dir_base = dest_dir[0..dest_dir_base_idx]<br /> dest_dir_name = dest_dir[(dest_dir_base_idx + 1)..dest_dir.length]<br /><br /> # Make sure the parent of the destination directory exists<br /> mkdir_rslt = %x[mkdir -p #{dest_dir_base}] if !File.exist?(dest_dir_base)<br /><br /> # turn execution over to the rsync command<br /> exec SSH_ORIGINAL_COMMAND<br />else<br /> # check if the command is trying to change the link<br /> linkCommand, prev_dir, dest_dir = /^link ([^ ;]+) ([^ ;]+)$/.match(SSH_ORIGINAL_COMMAND).to_a<br /><br /> if !linkCommand.nil?<br /> dest_dir_base_idx = dest_dir.rindex('/')<br /> dest_dir_base = dest_dir[0..dest_dir_base_idx]<br /> dest_dir_name = dest_dir[(dest_dir_base_idx + 1)..dest_dir.length]<br /><br /> # Update the symlinks<br /> if File.exist?(dest_dir)<br /> # delete previous symlink if it exists<br /> rm_rslt = %x[rm #{prev_dir}] if File.exist?(prev_dir)<br /><br /> # create new symlink to the latest destination directory<br /> ln_rslt = %x[ln -s #{dest_dir_name} #{prev_dir}]<br /> else<br /> $stderr.puts "Something went wrong, '#{dest_dir}' does not exist to link to. Previous link will not be touched."<br /> exit<br /> end<br /> else<br /> $stderr.puts "Illegal command passed to SSH '#{SSH_ORIGINAL_COMMAND}'"<br /> exit<br /> end<br />end<br />


I'm sure there is a way to do what the wrapper does in bash but I happen to be more comfortable with ruby doing the string parsing. If anyone wants to provide a bash script for doing the same thing I'd be more than happy to see it.