Shell script to backup database and send it to remote server automatically

Database backup script
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This article explains how to create a database backup script to send the backup to remote server  without any manual intervention. For security reasons or to enable disaster recovery it is important to keep database backup copies on some additional server outside your network.

The process to create a script for database backup and to autosend it to a remote server is not really so complicated as many would think.

To make it simpler let’s divide the whole task in 3 different sub tasks

  1. Create a backup file of your database.
  2. Authorize the origin server i.e. Your current server to send the files to the remote server (So that the remove server knows that it is receiving the files from a genuine source)
  3. Create a script to simply SCP the files from the origin server to the remove server

Above mentioned are mandatory steps. Additionally you may also want to create a log file to log the status of every step just in case if something goes wrong.

Now lets discuss each step in detail

Step 1: Create a backup file of your database

The backup file of your database can simply be a compressed sql file. There are lot of automated tools to achieve this. But to create a script is also quite simple.

For those who want to script everything here is a sample script (and assuming you have only one database)

Above command just creates a dump of the database. The dump is in sql format. Let’s say db.sql

The size of the file however would be too big (depending upon your database) as it is an uncompressed database file. So you may wish to change the above command to output a gzip or bzip2 file.

GZip

bzip2

Note: Although the compressing provided by bzip2 is better than Gzip it takes much longer (around 6-10 times) to compress a file in comparison to Gzip. However in our case the process will mostly run during the night and will be automated so you might wish to use bzip2. So in this case both the options are ok.

Step 2: Authorize the origin server to send the files to the remote server

As you would have guessed this steps is to avoid password prompts so that the process happens automatically without any manual intervene.

It involves only 2 steps

A. Create an SSH key on the origin server

Command: ssh-keygen

This will create a key in your USER/.ssh folder with the name of the key provided while running above command.

When asked to enter passphrase, leave it blank (unless you will be caching the passphrase on the remote server)

If you want to use your current SSH keys thats fine too however they may have a passphrase on it. You can remove the passphrase using below command

Command: ssh-keygen -p

This command will first ask the ID of the key for which you wish to change the passphrase. Then it will prompt you to add the new passphrase. You can leave it blank.

 

B. Add the private key to the authorized_keys file on the remote server

This step is very simple. Just copy the public key (e.g. id_rsa.pub) contents and paste them on a new line in the authorized_keys file on the remote server

Note: Do not delete any content in this file. Just append the file with the contents of the key starting on a new line.

Step 3: Create a script to simply SCP the files from the origin server to the remove server

Final step is very simple. Here we will just be copying the files from the origin server to the remote server using below command

 

Here the port number is of the remote server where you will be sending the files. If the scp port is non standard or non default only then -P PORT_NUMBER option is necessary