syncwith

#!/bin/bash

# ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
#
# USAGE:
#
#	syncme user@target.tld
#
#		OR
#
#	syncme target.tld
#
# SETUP:
#
#	Create id_dsa and id_dsa.pub on the client
#	machine, and copy id_dsa.pub into authorized_keys
#	on the target.
#
#	Follow the instructions at:
#
#		http://kimmo.suominen.com/docs/ssh/
#
# CUSTOMIZING:
#
#	This script is very simple.  You must read through
#	it and customize some of the paths, as appropriate.
#	Look for {bin,Documents,work} in the script below
#	and fix them up.  This pattern appears twice in the
#	script.  It could be parameterized, but you'd have
#	to figure out the quoting rules for the second
#	instance and get it just right.
#
# GETTING ORGANIZED:
#
#	Of course it is possible to just rsync your entire
#	home directory, but that is slow and wasteful.
#	If you did that, you'd end up replicating every
#	large package you downloaded, backing up all of your
#	temporary files, etc.   Yuck.
#
#	A little organization can make syncronization much
#	more efficient.  I have my home directory organized
#	as follows:
#
#		bin		my scripts
#		Documents	non-code docs not under revision control
#		Personal	documents that are not synced with work machines
#		work		code not under revision control
#		local		local checkout of everything under revision control
#		Downloads	folder firefox saves downloads to
#		WhatIsInstalled	installed software, usually moved from Downloads folder
#		VirtualMachines	for vmware
#		tmp		random trash
#
#	Of these folders, I sync bin, Documents and work.
#	You might sync more or less, but you should not
#	sync files under revision control; that is a bad idea.
#	Use svn / cvs checkin and checkout directly to sync
#	files under revision control.
#
# WARNING:
#
#	This script does two-way syncs between multiple machines.
#	If you delete a file on one machine and then sync, the
#	deleted file will come right back.  If you move a file
#	to a new folder and then sync, then you will have two
#	copies of that file on both machines.
#
#	It helps to get organized before using this script for the
#	first time, and it is also helpful to stay organized and
#	put things where they belong before syncing.  Only
#	"clean house" occasionally; then, move away the target
#	directories on all other machines to another spot,
#	clean up the source directories, and run sync again to
#	make a fresh copy on the other machine.
#
# ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

#
# Check to see if this script is already being
# run under ssh-agent, with our id specified via
# ssh-add.
#
hasID=`ssh-add -l | grep '/home/'$USER'/.ssh/id'`

#
# Check to see if it's time to call rsync, or if
# we still need to invoke ssh-agent.  We will go
# ahead and call rsync if we have been called recursively
# ("sync" in the second parameter), or if ssh-add -l
# reported that we've already cached a key for this
# system in memory.
#
if [ "X$2" = "Xsync" ] || [ "X$hasID" != "X" ] ; then

	#
	# If we do not have a key yet, then prompt
	# for one.
	#	
	if [ "X$hasID" = "X" ] ; then
		ssh-add
	fi
	
	#
	# Check to see if we have a username in the target
	# or not.  If we do not, then we will use $USER
	#
	if [ X`echo "$1" | grep "@"` \!= "X" ] ; then
		remoteuser=`echo $1 | sed -e 's/@.*//'`
		target=$1:/home/$remoteuser
	else
		target=$USER"@"$1:/home/$USER
	fi
	
	echo "Target is $target"
	
	#
	# Push the documents in the folders to sync
	# from this machine to the target machine.
	#
	# -a == -rlptgoD
	#
	# Flags we've selected:
	#
	#	-r	recursive
	#	-l	copy symlinks as symlinks
	#	-p	preserve permissions
	#	-t	preserve times
	#	-g	preserve groups
	#	-o	preserve owner
	#	-D	preserve device files
	#
	#	-C	skip files the same way that CVS does
	#	-u	skip files that are newer on the receiver
	#	-v	verbose
	#	-z	compress data during transfer
	#
	rsync -autvz \
		--exclude='~*' \
		--exclude='.~*' \
		/home/$USER/{Documents,work} \
		$target


	#
	# Next, pull files that have changed on the
	# target machine back over to this machine.
	#
	rsync -autvz \
		--exclude='~*' \
		--exclude='.~*' \
		$target/'{Documents,work}' \
		/home/$USER

else
	#
	# Make a recursive call to re-invoke this
	# script using ssh-agent.  Ssh-agent will
	# cache our keys in memory (keys are cached
	# via calls to ssh-add), so we do not have
	# to enter a password every time we call
	# rsync.
	#
	ssh-agent $0 $1 sync
fi