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Creating a MySQL or MariaDB user and granting permissions to him to access a specific database and be able to write data on it is a very usual task that is necessary to perform each time you install a new application based on any of these database engines, like web applications running on top of LAMP stack. Whether it is a simple WordPress, or a more complex application tailor made, one way or another you will always have to complete these steps at some point before its deployment.

One of the most targeted goals when optimizing a website for page load speed is to get a good score on Google PageSpeed Insights test. But it is not enough to work hard on optimization, achieve a good score and go to sleep. It is essential to periodically monitor score changes as a website evolves and undergoes changes over time which affect this metric.

Here’s a little script that will allow you to automatically track Google PageSpeed Insight score and be alerted if it falls below a custom value.

When we completely fill up an ext4 filesystem mounted on a partition hosted in an EBS volume of Amazon Web Services and we can not do anything to free space because we do not want to lose any of the stored data, the only solution is to grow up the volume and extend the associated partition up to 100% of its capacity to obtain free space again.

We start in our example with a 50 GB volume full to 100%. We want to extend it to double the size, 100 GB:

Since the key combination Control+s is widely used as a shortcut to save files in GUI applications such as text editors, image editors, web browsers, etc. sometimes you are betrayed by your subconscious when you are working from the Linux command line and you use that same key combination when you are for example editing a Vim document when trying to save it. Then you notice that no key answers, the shell is locked and you can no longer do anything else in it.  Even worse, you get a cold sweat because you can’t continue editing your document and you can’t save the changes.

It is often common to embed a Facebook «Like» button on your website so that on the one hand you show the number of followers of your Facebook page and on the other hand you invite the user to click on it to start following your page. However, this type of buttons tend to overload a website quite a lot because they consist of Javascript code that dynamically generates the button with the updated number of followers and the functionality needed to give a «Like». This means that every time you load a page of your website you have to send 11 extra requests to the Facebook servers to download all the necessary elements. Given that these servers are currently located on the west coast of the United States and are not available through any CDN or similar service, depending on where the user is located, it is likely that each of these requests will have to cross half the globe to complete the download. All this causes your website to slow down unnecessarily and its loading speed is affected, which is quite negative in multiple aspects.

Through the following instructions you can easily get a permanent access_token to automatically connect your applications to a Facebook page and be able to obtain for example your number of followers periodically, get new likes or comments in real time, publish new entries in the timeline, or any of the possibilities offered by the Facebook Pages API.

2.1 Go to My apps.

2.2 Create new app, for example AppMipagina:

The CPU average load value is a very important metric to understand the behavior of a Linux system, and especially its current and recent past status. Many times there is confusion between this term and percentage of CPU usage, but differences are important. In this article I will try to explain the true meaning of both and how to tell if a Linux box is overloaded or underutilized.

It is shown in the different monitoring tools (top, atop, htop, etc.) as a set of 3 values representing the average CPU load experienced by a Linux system in the last 1, 5 and 15 minutes respectively. Therefore, a first difference is that these are historical values, while the percentage of CPU usage is typically measured in intervals of between 1 and 5 seconds, so their value is usually almost instantaneous.

I am a strong supporter of simplicity and the principle that less is more, but as far as security and performance of information systems is concerned, we must be able to strike a balance between keeping things simple and exposing ourselves as little as possible to potential threats while trying to obtain the maximum performance of all system elements involved.

It is a common practice that the various distributions of Linux, and even the images used to launch Linux virtual server instances as in the case of AWS AMI’s, implement by default an extremely simple partitioning scheme consisting in a single partition that covers the entire disk. It is in this only partition where the root filesystem (/) is mounted and in which all the directories that configure the file hierarchy of a Linux operating system are placed.

When we try to know a computer’s architecture and performance at CPU level using Linux commands like nproc or lscpu, we often find out that we are not able to properly interpret their results because we confuse terms such as physical CPU, logical CPU, virtual CPU, core, thread, socket, etc. If we add concepts like HyperThreading (not to be confused with multithreading), we are in a situation where we can not be sure how many cores our box has, we don’t understand why commands like htop indicate that we have 8 cpus when we thought we had bought a single quad-core processor, etc. In short, it’s a mess.

One of the most common and tedious tasks of a sysadmin is to prevent file systems become completely full, because when a server runs out of space the consequences are unpredictable. Depending on how you structured the root file system and if it is divided into different partitions or volumes, those consequences will be more or less severe, but in any case undesirable.

In any case it is always better to be safe than sorry, so use tools that perform automatic log rotation as logrotate and custom scripts to monitor and conduct periodic emptying actions to prevent file systems to get full. However, still using these prevention methods it is for sure it will be many times when you will have to act manually to troubleshoot problems.