got it working well on bionic
My phone is rooted.
I had to copy a file containing my password to the same folder as the rsync bin file. I also had to chmod 600 the file.
So copy rsync to /system/xbin and, in my case, rsyncd_passwd to /system/xbin
Then chmod 600 /system/xbin/rsyncd_passwd
then remount to ro.
Also another note is I couldn't use the archive "-a" switch. I could do this:
rsync -rv --delete --password-file=/system/xbin/rsyncd_passwd "/mnt/" "firstname.lastname@example.org::/"
On a side note, this is not encrypted. Rsync on port 873 defaults to just compression. This doesn't rsync over ssh yet. Someone has to have openssh for android first or something smaller.
AGAIN this is what I had to do to make this work. I am still working on getting a cron or some other scheduler to run this @daily for me. This is great! I have linux functionality on MY FREAKIN PHONE!