An overview of the PC Real Time Clock (RTC)

Introduction

Have you ever thought how the computer is able to display the correct time after you power on the system? There is a component called the RTC in the computer which stores this date and time information when the computer is turned off.

I will talk about how to read/write the date and time and use other features of the RTC using command-line tools, Linux RTC driver and also a low level direct access to the RTC internal registers.
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Find process IDs of a running process by name

In this post I will talk about a procedure to find the process IDs of a running process by name, which can then be used to send signals or do other stuffs. For example if you have multiple instances of bash opened, this should be able to get you the list of process IDs (PIDs) of the bash instances.

Firstly, a shell utility is already available called pidof which is a part of the sysvinit-tools package. There are a whole bunch of tools in this package which lets you query PID based on different requirements, send signals to set of processes, etc. Just check out the stuff.

I will only mention the outline of how this is done and post the sourcecodes to do it. After that this can be extended to have many features just like the tools of sysvinit-tools package or more.
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What are ID3 Tags all about?


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When you play a music file in your favourite music player, or in your portable media player the track name, album, artist, lyrics gets displayed. You can search the songs with artists, album names. Even some of the tracks come with album art too, but there is no image file anywhere. The question generally arises, where does these information come from? The answer is straight forward; this metadata about the audio track is stored inside the audio file itself. The different audio files need different codecs. Different audio format files also have different such metadata systems. For example The Vorbis comments, APE tag, ID3 tags etc.

The most common and popular audio media (although not the best) is the mp3 . Mp3 audio format stores this metadata inside the music file, either at the beginning or at the end or at both locations. The music metadata system used with mp3 is called an ID3 Tag.
We will rip off the ID3 tag and check out what’s inside it in this article. We will discuss about ID3v1.x and ID3v2.x tags.

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