Rsync
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The swiss army knife of backups and file transfers
rsync is a utility for efficiently transferring and synchronizing files between two locations either locally or across networked computers. It is particularly useful because it facilitates fast incremental file transfer, ideal for backups.
Examples
Commonly used default options
/usr/local/bin/rsync -avHP --exclude=.snapshot/ --exclude=.zfs /isilon/fs/vol1/hag/user1 /ironbank/gr/ >> user1.log &
/usr/local/bin/rsync instead of rsync so that my scripts dont have to worry about $PATH being set properly.
a - Archive mode preserving all attributes
v - Verbose - listing even the names of files being transferred - for logging purposes. May be too much in some cases.
H - Preserve Hard links
P - keep partially transferred files and show progress
--exclude - Exclude a pattern. In my case Netapp's .snapshot format and ZFS's .zfs format to exclude copying snapshots.
>> - Append to the log
& - Run this as a background process in shell.
Replicate a directory tree at destination
You get you will end up with /pre_existing/dir/new/x/y/z/To replicate partial directory path,
You get /pre_existing/dir/y/z/ at destination.