Sunday, 15 July 2012

Use rsync command over ssh to to take backup of files.


Today we are going to discuss over "how to use rsync command over ssh to take backup of files". Before that let's know little bit about rsync itself.

rsync : 


rsync is a little Linux utility that synchronizes filesystems from one place to another by only copying diffs (deltas) of files that have changed. rsync optionally compresses the files ont-the-fly before transfer (to save transfer time) and may be used in conjunction with rsh or ssh to perform remote file transfers. rsync may be used as a backup or mirroring utility.

The advantage of using rsync over other archive and copy utilities such as tar, dump and rcp are:

(1) rsync can use ssh as a secure channel to transfer files over the network.

(2) It provides an ability to retain ownership and permission of files being transferred.

(3) It enables files and directories to be synchronized (deleted files are deleted from the last replication), and 

(4) transfers only "delta" files that are changed from last replication making transfer much faster. 

If rysnc is used without the ssh, it uses the TCP port 873. 

To more about rsync command you can follow these links


You can run rsync command as follow :

Example :

rsync -iavz --log-file=/usr/dirtyhandsphp/backups/`date +%d%b%Y`_rsync.log -e ssh /var/www/manual /usr/dirtyhandsphp/backups/backup_`date +%d%b%Y`

--log-file  :  saves a copy of the rsync result to a logs_date-stamped file.
-a  : archive mode
-v  : verbose mode
-z  : Compress files before transfer

 
It would copy manual folder and it's files from /var/www/ to /usr/dirtyhandsphp/backups/backup_`date +%d%b%Y`. Files would get copied in compressed mode and a logfile with nominature `date +%d%b%Y`_rsync.log would be created in /usr/dirtyhandsphp/backups/ directory.

Note : If you are running this command from backend and not going with logs file option then there is no need of using verbose (-v) mode.


How to check if rsync ran successfully or not :  


rsync command returns an exit code after execution. You can check exit codes list here : 


If it returns no code it means it ran successfully without any problem so code is 0. Otherwise it would return a particular code. If you are writing a shell script which would be exected automatically at a particular time from back-end and want to put some logic on success or failure of the command. You can do as following :


#!/bin/bash

rsync -iavz --log-file=/usr/dirtyhandsphp/backups/`date +%d%b%Y`_rsync.log -e ssh /var/www/manual /usr/dirtyhandsphp/backups/backup_`date +%d%b%Y`

 if [ "$?" = "0" ] ; then
        #echo "Backup Completed
 else
        #echo "Backup Failed"
 fi
 exit


Thanks!!!!!!!!! Enjoy Programming :)



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