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Showing posts from December, 2011

Build Wine rpm with 32 bit application support

Wine is a software to allow running Windows applications in Linux, MAC etc. platforms. It is available for installation from package managers like yum (RHEL, CentOS) and apt (Ubuntu). You can find more details on how it works in Wine wiki.

But the default Wine package available from package manager does not have support for 32 bit Windows applications. This was the case for me. In Redhat Enterprise Linux 7.3, the wine package did not contain support for 32 bit windows applications. So the only option was to build a separate rpm of wine which will include this support.

All the steps are executed on a RHEL 7.3 VM (x86_64).

Step 1
Download and run shell script which will make wine 64 and 32 support for RHEL: https://github.com/zma/usefulscripts/blob/master/script/install-wine-i686-centos7.sh It accepts a version no. as CLI parameter e.g. 2.0.3

The script installs wine in /usr/local/ directory by default. We can verify the files that are being copied for wine using "cd /usr/src/wine-2.0.…

Call an external program from MySQL trigger

MySQL is the choice of many when it comes to database. Its free and quite robust.
During one of our prototype implementations we had a requirement of calling some external processes when there is a change in a MySQL table. MySQL triggers are provided for the same purpose. They get executed when the table is changed in certain ways that is specified by the programmer. Now it is very easy (rather trivial) to do some thing in other MySQL database tables when trigger gets fired. But, our requirement was to call a C program.

Fortunately MySQL provides a way to implement your own functions, its called User Defined Functions (UDF). The "how to" is here. Now that we know, how to define your own functions and call them from MySQL events, we need to write our logic in a C program by following the interface provided by MySQL and we are done.

Wait a minute. That is already done by somebody. They have made a library of UDFs. One of them, LIB_MYSQLUDF_SYS does exactly what we want. It al…