Linux Admin Zone

Hosting my wordpress blog in GoDaddy was a big mistake, I realized this when one of my regular visitor alerted me that my blog is having suspicious activity. I promptly downloaded all of my blog files in my local system to scan and that operation took around 2 hours because of terrible FTP download rate from GoDaddy. Upon looking inside the files, almost all php files were having suspicious code and certainly infected by some malware. I did a clean of each and every file including database scan for any malicious records, users etc (referred this while cleaning). Uploaded all new files by replacing existing completely. I checked my logs and thought for a while about why such thing happened. My wordpress version was latest, strong FTP password and in fact no regular FTP activities from my side. I’ve Mac for myself. So I didnt’ found any reason and forgot that incident.

MySQL stopped default inclusion of InnoDB in latest 5.1.x, so if you need InnoDB, you have to compile it from source. I have done following steps in CentOS 5.4 server to compile MySQL and optimize it later for a heavy site:

1. Remove earlier installation of MySQL, if any and download source rpm from MySQL site. I’ve also removed earlier installation of PHP here to upgrade it:

$ rpm -e php-mysql mysql-server php php-devel php-pear

Download the latest source rpm from MySQL download site, you will get source rpm like below and install it. Installation of source rpm will put it as tar file in /usr/src/redhat/SOURCES, make sure to create /usr/src/redhat/SOURCES directory before installation:

Recently I was in need to convert all databases of a MySQL server from MyISAM engine to InnoDB. They are facing severe issues due to table level locking in MyISAM and wanted move to InnoDB. This task can be a mammoth work but if you work little smarter, all you need to execute few statements and look at the progress while having cup of coffee. Also note that you can convert in both side, means from MyISAM to InnoDB and from InnoDB to MyISAM using these commands.

There are plenty such tools which are definitely very useful for Linux admins. Here I am just trying to figure out 5 of such useful tools which are used by a normal Linux administrator in day to day operations. A tool which I think is most useful may not fit in your usage and its definitely possible that you know some awesome tool which I forgot to include here, for such case, I am requesting hereby to please mention the tool in comments. One more thing, I am mentioning here tools which are somewhat optional and not absolutely required for everybody and excluding tool which have no viable alternative and every Linux admin have to use them.. such as SSH, SCP etc.

Sometimes in large deployments, there are cases when MySQL server, setup by you long time back which has been in use by multiple teams in your organization, needs some change or update or intrupption in its service and you are in need to know how many clients are there which connects to this server.

One way to know is to check user table in ‘mysql’ database, you might have created individual users/databases for your clients/users. But over the time, unless taking care seriously, we tend to forget the exactly how many users/scripts/machines are there making connections. May be you have used same read-only user in various scripts scattered over many machines which you’ve created just for a single client.