Category Archives: Linux

Recover an #Oracle installation from a full disk backup in #Linux

Reinstalling things like Oracle is always a hassle and takes about one day to make it work. Lucky for me I made a full back-up of my old disk when I upgraded to a new laptop. On the new laptop I did a fresh install of Fedora 28. The idea is to migrate my old… Read More »

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Disable core dump generation on #Linux

Generation of core dumps that result in freezing the Linux system is another common issue in the new Linux kernels discussed on many forum threads. Same as the bug of kswapd0 discussed here Kswapd0 going haywire this can become very annoying. It seems that lately someone tries to add developer features turned on by default… Read More »

#Apache #Kafka solutions going mainstream

I like when solutions you are excited about and are first seen as “experimental” start to go mainstream. This happened with containers (Docker, CoreOS, Kubernetes etc.) which are now the hottest topic in DevOps right now. The same is happening now for Apache Kafka which was adopted by no other than “Goldman Sachs” for their… Read More »

A solution for kswapd0 going haywire on #Linux

This is a common issue in the new Linux kernels discussed on many forum threads. There is a long thread here about this problem. In short the issue is that when you run out of memory “kswapd0” a kernel process than manages virtual memory will start moving “old memory entries” to swap. The “run out… Read More »

Find in Linux if your installed RAM is ECC

Sometimes really simple questions are hard to answer. One day I got the question from a coworker: “How do I know if some installed RAM is ECC or not”. The easiest way is to use dmidecode command that dumps in Linux all the system characteristics. But because I had no idea how to see if… Read More »

Convert certificate from DER to PEM format

Sometimes you get a CA certificate in DER format and some application requires it in a PEM format. OpenSSL to the rescue:

#Docker volumes and Selinux

When running complex environments on Docker on Linux again we face the mighty selinux. There are plenty of selinux alerts generated when I start my environment when the host machines have selinux enabled and volumes are used by the containers. Setting selinux permissions is hard and tedious and many people just prefer to disable it.… Read More »

Linux: Save a pdf presentation to individual image slides

There is a very simple way to save a pdf presentation to individual jpeg images of the slides using convert.

where: – density 300 specifies the DPI used to read the pdf. – presentation_page_%04d.jpg is a name pattern for the saved images As a result if presentation has 20 slides we get image slides… Read More »