Raspberry PI, by default, has only one memory available – an SD card that also holds the kernel itself. Unless you are using a large SD, eventually, you will run out of space -especially if you are dealing with media files or playing with the camera module. The easiest and cheapest way of expanding memory is to use a USB Flash drive. If you are accessing PI from the terminal screen, then probably one of the built-in USB ports is free, and you can attach a drive directly to it; otherwise, use USB HUB – better with an external power option.
Recently I’ve received a Raspberry pi camera board. So decided to make a post about it. Raspberry PI comes with two interesting connectors onboard. One is between Ethernet and HDMI, and another is near GPIO. The one closer to the Ethernet connector is CSI (Camera Serial Interface) bus interface. This interface is common in mobile phones with cameras. This interface is specially designed for high data rates that are necessary for transferring pixel data. The camera board is a small (25mm x 20mm x 9mm) board where a fixed-focus 5MP camera module (OV5647) is assembled. The camera connects to Raspberry Pi via a 15cm ribbon cable. Camera module is capable of producing 1080p images at 30fps or 720p at 60 fps and 640x480p at 60/90 fps. Obviously, such images and fps require a high-speed interface and processing. So CSI is connected directly to Raspberry Pi GPU, which can process images without ARM intervention. This is why the camera module is a much better choice than the USB camera, which occupies the main processor and slows down the whole system. GPU processing also benefits with fast H264 video encoding and JPEG compression capabilities.
Probably this would be unwise to go through a long list of available Unix commands. It is quite long, and there is no reason to point out each of them here. You can take a look at some basic ones in the following list. It is more important to learn how to use them and get the desired result by building more complex commands. Commands can also be combined into a single line using piping. In this case, the output of one command becomes the input of the next one and so on. Let’s go with few examples. We all know that Raspberry Pi comes with Python installed. So we should expect to find lots of .py files here: sudo find / -name *.py this throws us large list of file names: Finding and displaying files that way is useless. Viewing is even more painful. Let’s say we simply want to count all .py files. For this, we use the same command, but instead of throwing the list to the terminal, we feed it to another command that does the counting of lines (we get every file in a new line):
Previously we looked at simple terminal commands like ls, cd. We know that ls output all files in the working directory. But in practice, command without options and parameters is almost useless. You may need to list special files or list files from the specified directory in more complex situations without going to it. This is why UNIX commands are run with options and parameters command [options] [parameters] There can be more than one option and parameter for a single command. For instance, we used a cd .. command to go to the previous directory. Dots .. are nothing more than parameters. Let’s see what parameters we have with the ls command. ls -l It displays a list of files in a long format. You can see that we get much more information by adding a simple option -l. Let’s say we want to display files in a long format from a different than a working directory. Then we need to type in the path to the directory as a parameter.
Computer users today are so attached to graphical interfaces. Sometimes it seems that people help computers to do the tasks. Can you imagine how many mouse clicks are required to do something simple? This is visible when the task is cyclic like “find, sort, delete.” Sometimes you find yourself just clicking the mouse and not seeing the result. What you would do half a day clicking the mouse can be performed with the single command line. The question is how to be that smart and feel like a fish in the water in front of the command prompt, shell, or bash – call it however you want. It is a system program that accepts typed commands from used and performs tasks. If you look deeper at almost any program with the graphical interface, you will see that it is only a nice skin that hides the same commands that run when the user clicks buttons. No graphical interface can cower all features of shell commands. So if you start dealing with Linux, then start being a friend to the terminal. Historically Unix computers even didn’t have a graphical interface, so all tasks were performed from the terminal screen. This is…
It’s been quite some time since my Raspberry Pi Model B arrived. All I’ve done is tried to run several things, blink GPIO with examples found on the Internet, set up a desktop computer for my daughter with TuxPaint. I never was a big fan of Linux; on the desktop computer, I always use Windows for my daily tasks. With cheap single-board computers like Raspberry Pi, people looked at Linux from a different perspective. We can notice an increased interest in Linux, how to do this, and this. Who works with Linux long time? It is just another computer where they can work with it and make cool things right away. But for us like me, it’s a good chance to get to know Linux better and learn a few tricks.
Is there anyone who didn’t hear about Raspberry Pi? It’s like the second thing after Arduino. And this is the result of the right idea at the right time. Many Linux boards around that don’t cost a fortune, but they didn’t make it to the masses. And mainly, they were used by advanced users who know Linux well enough. Raspberry Pi pros Raspberry Pi changed things pretty drastically. And there are several key factors why: