Automate Backups on Linux

By Martyn Honeyford
2005-04-20

Scripting a Backup Process

Our next task is to create the shell scripts, which will perform the necessary backup operations. The goal is to perform a complete database backup of servers 1 and 2. In our example, each server is running the MySQL database server and we'll use the mysqldump command-line utility to export a few database tables to an SQL import file.

Listing 10. The dbbackup.sh shell script for server 1

#!/bin/sh



# change into the backup_agent directory where data files are stored.

cd /home/backup_agent



# use mysqldump utility to export the sites database tables

mysqldump -u sitedb -pG0oDP@sswrd --add-drop-table sitedb --tables

tbl_ccode tbl_machine tbl_session tbl_stats > userdb.sql



   # compress and archive

   tar czf userdb.tgz userdb.sql

On server 2, we'll place a similar script which backs up the unique tables present in the site's database. Each script is flagged as executable using:

[server1]:$ chmod +x dbbackup.sh

With a dbbackup.sh file on servers 1 and 2, we return to the offsite data server, where we'll create a shell script to invoke each remote dbbackup.sh script prior to initiating a transfer of the compressed (.tgz) data files.

Listing 11. backup_remote_servers.sh shell script for use on the offsite data server

#!/bin/sh



# use ssh to remotely execute the dbbackup.sh script on server 1

/usr/bin/ssh backup_agent@server1.com "/home/backup_agent/dbbackup.sh"



   # use scp to securely copy the newly archived userdb.tgz file

   # from server 1.  Note the use of the date command to timestamp

   # the file on the offsite data server.

   /usr/bin/scp backup_agent@server1.com:/home/backup_agent/userdb.tgz

   /home/backups/userdb-$(date +%Y%m%d-%H%M%S).tgz



   # execute dbbackup.sh on server 2

   /usr/bin/ssh backup_agent@server2.com "/home/backup_agent/dbbackup.sh"



   # use scp to transfer transdb.tgz to offsite server.

   /usr/bin/scp backup_agent@server2.com:/home/backup_agent/transdb.tgz

   /home/backups/transdb-$(date +%Y%m%d-%H%M%S).tgz

The backup_remote_servers.sh shell script uses the ssh command to execute a script on the remote servers. Because we've set up passwordless access, the ssh command is able to execute commands on servers 1 and 2 remotely from the offsite server. The entire authentication process is now handled automatically, thanks to keychain.

Tutorial Pages:
» No Excuses: do-it-Yourself, Secure, Distributed Network Backups Made Easy
» Simple Backups
» Advanced Backups
» Secure Remote Access Using Public/Private Keys
» Automating Machine Access Using SSH-Agent
» Simplifying Key Access Using Keychain
» Scripting a Backup Process
» Scheduling
» Verifying Your Backups
» Additional Security Precautions
» Conclusion
» Resources

First published by IBM DeveloperWorks

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