Rsync comes pre-installed on many systems including Red Hat, Ubuntu and Solaris. Rsync is a useful tool for performing remote backups. It is very efficient as it only backs up the changes or differences in tany changed files rather than the whole file.
BASIC EXAMPLE – LOCAL BACKUPS:
In this example you can use rsync to perform a backup from your local system to another location on your local system. This could be used to back up files onto a mounted filesystem or another hard disk. It is similar to the copy (cp) command but more efficient.
rsync -av /home/jonny/temp/source/ /home/jonny/temp/destination
The 'a' option is for all files and 'v' is for verbose. I have a trailing slash on the source directory otherwise the rsync command will create a directory
/home/jonny/temp/source/destination/backedupfiles
rather than
/home/jonny/temp/source/backedupfiles
BASIC EXAMPLE – REMOTE BACKUP:
To backup a directory from a local machine to a remote machine asecure shell account is needed on the remote machine and the command for a remote machine named 'barney' would be:
rsync -a –delete -e ssh /home/jonny/temp/rsync/source/ jonny@barney:/home/jonny/rsync/
The delete option ensures that any files deleted in the source directory will be deleted in the remote directory. This ensures you keep a mirrored backup without the junk. On logging in you are asked for your password on the remote system.
SCHEDULING BACKUPS
To schedule backups on a *nix system you would obviously use Cron.
crontab -e
An add an entry for your backup e.g.
10 2 * * * /usr/bin/rsync -a --delete /home/jonny/source/ destination/
