Using rsync For Transferring Files Under Linux or UNIX

rsync is a free software computer program for Unix and Linux like systems which synchronizes files and directories from one location to another while minimizing data transfer using delta encoding when appropriate. An important feature of rsync not found in most similar programs/protocols is that the mirroring takes place with only one transmission in each direction.

So what is unique about the rsync command?

It can perform differential uploads and downloads (synchronization) of files across the network, transferring only data that has changed. The rsync remote-update protocol allows rsync to transfer just the differences between two sets of files across the network connection.

How do I install rsync?

Use any one of the following commands to install rsync. If you are using Debian or Ubuntu Linux, type the following command:

# apt-get install rsync

OR

$ sudo apt-get install rsync

If you are using Red Hat Enterprise Linux (RHEL) / CentOS 4.x or older version, type the following command:

# up2date rsync

RHEL / CentOS 5.x or newer (or Fedora Linux) user type the following command:

# yum install rsync

Always use rsync over ssh

Since rsync does not provide any security while transferring data it is recommended that you use rsync over ssh session. This allows a secure remote connection. Now let us see some examples of rsync command.

Comman rsync command options

--delete : delete files that don’t exist on sender (system)
-v : Verbose (try -vv for more detailed information)
-e "ssh options" : specify the ssh as remote shell
-a : archive mode
-r : recurse into directories
-z : compress file data

Task : Copy file from a local computer to a remote server

Copy file from /www/backup.tar.gz to a remote server called openbsd.nixcraft.in

$ rsync -v -e ssh /www/backup.tar.gz jerry@openbsd.nixcraft.in:~

Output:
Password:
sent 19099 bytes  received 36 bytes  1093.43 bytes/sec
total size is 19014  speedup is 0.99

Note that symbol ~ indicate the users home directory (/home/jerry).

Task : Copy file from a remote server to a local computer

Copy file /home/jerry/webroot.txt from a remote server openbsd.nixcraft.in to a local computer’s /tmp directory:

$ rsync -v -e ssh jerry@openbsd.nixcraft.in:~/webroot.txt /tmp

Task: Synchronize a local directory with a remote directory

$ rsync -r -a -v -e "ssh -l jerry" --delete /local/webroot openbsd.nixcraft.in:/webroot

Task: Synchronize a remote directory with a local directory

$ rsync -r -a -v -e "ssh -l jerry" --delete openbsd.nixcraft.in:/webroot/ /local/webroot

Task: Synchronize a local directory with a remote rsync server or vise-versa

$ rsync -r -a -v --delete rsync://rsync.nixcraft.in/cvs /home/cvs

OR

$ rsync -r -a -v --delete /home/cvs rsync://rsync.nixcraft.in/cvs

Task: Mirror a directory between my “old” and “new” web server/ftp

You can mirror a directory between my “old” (my.old.server.com) and “new” web server with the command (assuming that ssh keys are set for password less authentication)

$ rsync -zavrR --delete --links --rsh="ssh -l vinay" my.old.server.com:/home/lighttpd /home/lighttpd

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