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The Ultimate Raspberry Pi Commands Cheat Sheet

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The Raspberry Pi is the most popular single-board computer (SBC) available. Just $35 gets you a powerful, fully-fledged Linux computer with Wi-Fi, Bluetooth, and 40 connected general-purpose input/output (GPIO) pins. It’s no surprise that the Raspberry Pi is equally popular between professional engineers, computer hobbyists, makers, and in the education sector.

While the Raspberry Pi runs on Linux, there are a few more features that you’d find in a common Linux distribution. The addition of GPIO pins, along with the two main libraries supporting them, means much more to remember!

That’s why we’ve prepared this handy cheat sheet for day-to-day Raspberry Pi usage.

FREE DOWNLOAD: This cheat sheet is available as a downloadable PDF from our distribution partner, TradePub. You will have to complete a short form to access it for the first time only. Download The Ultimate Raspberry Pi Commands Cheat Sheet.

The Ultimate Raspberry Pi Commands Cheat Sheet

Command Result
Raspbian OS Terminal
cat [name] Show the contents of the file [name]
cd .. Change to parent directory
cd [path] Move to the directory at [path]
cd / Change to root directory
cd ~ Change to your home directory – usually “/home/”
chmod [who][+,-,=][permissions] [name] Change the permissions for a file
chmod 777 [name] Allow all users to read, write and execute the file [name]
chmod u+x [name] Allow the user to execute [name]
cp -r [from] [to] Copy all files and subdirectories from source [from] to destination [to]
cp [from] [to] Copy a file from source [from] to destination [to]
find Search for files and their contents
grep ‘string’ [name] Search inside one or more files for occurrences of ‘string’
head [name] Return all occurrences of ‘string’ within file [name]
ls List the contents of the current directory
ls -a List all files including hidden files
ls -l List the contents of the current directory with more file information
ls [path] List the contents of the directory found at [path]
man [command] Open the manual/help page for [command]
man man Open the manual/help page for the ‘man’ command (helpception)
mkdir [name] Create a directory called [name] in the current working directory
mv -r [from] [to] Move all files and directories from source [from] to destination [to]
mv [from] [to] Move a file from source [from] to destination [to]
pwd Show the name of the current working directory
python/python3 –version Shows you what version of Python you currently have installed
rm -r * Remove all files and directories from the current working directory
rm [name] Remove the specified file
rm * Remove all files from the current working directory
rmdir [name] Remove the empty directory [name] from the current working directory
sudo [command] Superuser do. Execute [command] with elevated privileges (Allows you to do things you usually wouldn’t have access to)
sudo apt-get ​install [package] Install a package
sudo apt-get update Update the list of packages
sudo apt-get upgrade Upgrade the installed packages – must be run after sudo apt-get update
sudo ​chown pi:root [name] Change the owner of the file [name] to user ‘pi’ and set the group to ‘root’
​sudo raspi-config Launch the Raspberry Pi configuration menu
sudo reboot Safely restart your Pi
sudo shutdown -h now Safely shutdown your Pi immediately
sudo su Places you in the root directory with root user access – be careful with this!
tail [name] Show the end of file [name]
tar -cvzf [name] [path] Create compressed file [name] from the contents of [path]
tar -xvzf [name] Extract the contents of the compressed file [name]
wget [uri] Download the file found at [uri] on the internet
RPi.GPIO Library
import RPi.GPIO as GPIO Import the RPi.GPIO module into the python sketch
GPIO.setmode(GPIO.BCM) Use Broadcom pin numbers (GPIO 14, GPIO 15 etc)
GPIO.setmode(GPIO.BOARD) Use board pin numbers (4,5, 8 etc)
GPIO.getmode() Returns current pin numbering mode (BCM, BOARD, or None)
GPIO.setup([pin number], GPIO.IN) Set up the pin at [pin number] to be an input
GPIO.setup([pin number], GPIO.IN, pull_up_down=GPIO.PUD_DOWN) Set up the pin at [pin number] to be an input with internal pull down resistance
GPIO.setup([pin number], GPIO.IN, pull_up_down=GPIO.PUD_UP) Set up the pin at [pin number] to be an input with internal pull up resistance
GPIO.setup([pin number], GPIO.OUT) Set up the pin at [pin number] to be an output
GPIO.setup([pin number], GPIO.OUT, initial=1) Set up the pin at [pin number] to be an output with the initial value ‘1’
GPIO.output([pin number], 1) Set [pin number]’s value to 1. Note that 1, GPIO.HIGH and True are the same thing
GPIO.output([pin number], 0) Set [pin number]’s value to 0. Note that 0, GPIO.LOW and False are the same thing
i = GPIO.input([pin number]) Set the variable i to the value of [pin number]
if GPIO.input([pin number]): Use the value of [pin number] as a boolean in code
GPIO.cleanup() Reset all GPIO pins (good practice to call before leaving any program)
GPIO.VERSION Returns current RPi.GPIO version
GPIO Zero Library
LEDs
from gpiozero import LED Import the LED section of the gpiozero library
led = LED(17) Assign the ‘led’ variable to an LED on pin GPIO 17
led.on() Turn on the LED stored in the ‘led’ variable
led.off() Turn off the LED stored in the ‘led’ variable
led.toggle() Toggle the LED stored in the ‘led’ variable (if it’s off, turn it on and vice versa)
Motors
from gpiozero import Motor Import the Motor section of the gpiozero library
motor = Motor(17, 18) Assign the variable ‘motor’ to a Motor object containing the forward and backward drive pin numbers
motor.forward() Activate the forward pin of the variable ‘motor’
motor.backward() Activate the backward pin of the variable ‘motor’
motor.reverse() Reverse the current motor direction
motor.stop() Stop the motor
Buzzer
from gpiozero import Buzzer Import the Buzzer section of the gpiozero library
bz = Buzzer(3) Assign the variable bz to a Buzzer on pin GPIO3
bz.on() Turn the buzzer on
bz.off() Turn the buzzer off
bz.toggle() Toggle the buzzer’s state (if it’s off, turn it on and vice versa)
Servo
from gpiozero import Servo Import the Servo section of the gpiozero library
servo = Servo(17) Assign the ‘servo’ variable to a Servo on GPIO 17
servo.min() Move the servo to its minimum value
servo.mid() Move the servo to its middle value
servo.max() Move the servo to its maximum value
servo.value = 0.5 Move the servo to a set numerical point (min = -1, max = 1)
Raspi Camera Image
raspistill Command to take a still image with attached camera, modify with arguments below
–width, -w Set image width
–height, -h Set image height
–quality, -q Set JPEG quality (75 is most common)
–raw, -r Inserts raw Bayer data from the camera into the JPEG metadata
–output, -o Output filename (required for saving)
–latest, -l Add latest frame to filename
–verbose, -v Verbose debugging information during run
–timeout, -t Set a time to wait before capturing an image.
–encoding, -e Encoding to use for output file – jpg, gif, bmp, or png
Raspi Camera Video
raspivid Command to take a video using attached camera, modify with arguments below
–width, -w Set image width (between 64px – 1920px)
–height, -h Set image height (between 64px – 1080px)
–bitrate, -b Set bitrate in bits per second (i.e 15 Mbits/s = 15000000)
–output, -o Output filename (required for saving)
–verbose, -v Verbose debugging information during run
–timeout, -t Set a time to wait before capturing video
–framerate, -fps Specify the frames per second for recording

Expand Your Knowledge With Linux

These commands will help you navigate the Pi’s terminal, and program its GPIO pins. That said, this cheat sheet doesn’t even begin to scratch the surface. There is a huge depth of support for hobby components, cameras and screens for the Raspberry Pi. Listing them in one place is almost impossible!

The good thing is, since the Raspberry Pi is a Linux computer, you can reference a cheat sheet for general Linux systems to expand your knowledge even further.

Read the full article: The Ultimate Raspberry Pi Commands Cheat Sheet



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How Lifetime Access to Rosetta Stone Is Cheaper Than You Think

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Social distancing means we’re all spending more time in the house than ever… But once you’ve played every board game you own, replayed the entire Halo series on Xbox, and turned your backyard into botanical gardens, what else are supposed to do with your time?

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Read the full article: How Lifetime Access to Rosetta Stone Is Cheaper Than You Think



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Software that monitors students during tests perpetuates inequality and violates their privacy

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The coronavirus pandemic has been a boon for the test proctoring industry. About half a dozen companies in the US claim their software can accurately detect and prevent cheating in online tests. Examity, HonorLock, Proctorio, ProctorU, Respondus and others have rapidly grown since colleges and universities switched to remote classes.

While there’s no official tally, it’s reasonable to say that millions of algorithmically proctored tests are happening every month around the world. Proctorio told the New York Times in May that business had increased by 900% during the first few months of the pandemic, to the point where the company proctored 2.5 million tests worldwide in April alone.

I’m a university librarian and I’ve seen the impacts of these systems up close. My own employer, the University of Colorado Denver, has a contract with Proctorio.

It’s become clear to me that algorithmic proctoring is a modern surveillance technology that reinforces white supremacy, sexism, ableism, and transphobia. The use of these tools is an invasion of students’ privacy and, often, a civil rights violation.

If you’re a student taking an algorithmically proctored test, here’s how it works: When you begin, the software starts recording your computer’s camera, audio, and the websites you visit. It measures your body and watches you for the duration of the exam, tracking your movements to identify what it considers cheating behaviors. If you do anything that the software deems suspicious, it will alert your professor to view the recording and provide them a color-coded probability of your academic misconduct.

Depending on which company made the software, it will use some combination of machine learning, AI, and biometrics (including facial recognition, facial detection, or eye tracking) to do all of this. The problem is that facial recognition and detection have proven to be racist, sexist, and transphobic over, and over, and over again.

In general, technology has a pattern of reinforcing structural oppression like racism and sexism. Now these same biases are showing up in test proctoring software that disproportionately hurts marginalized students.

A Black woman at my university once told me that whenever she used Proctorio’s test proctoring software, it always prompted her to shine more light on her face. The software couldn’t validate her identity and she was denied access to tests so often that she had to go to her professor to make other arrangements. Her white peers never had this problem.

Similar kinds of discrimination can happen if a student is trans or non-binary. But if you’re a white cis man (like most of the developers who make facial recognition software), you’ll probably be fine.

Students with children are also penalized by these systems. If you’ve ever tried to answer emails while caring for kids, you know how impossible it can be to get even a few uninterrupted minutes in front of the computer. But several proctoring programs will flag noises in the room or anyone who leaves the camera’s view as nefarious. That means students with medical conditions who must use the bathroom or administer medication frequently would be considered similarly suspect.

Beyond all the ways that proctoring software can discriminate against students, algorithmic proctoring is also a significant invasion of privacy. These products film students in their homes and often require them to complete “room scans,” which involve using their camera to show their surroundings. In many cases, professors can access the recordings of their students at any time, and even download these recordings to their personal machines. They can also see each student’s location based on their IP address.

Privacy is paramount to librarians like me because patrons trust us with their data. After 9/11, when the Patriot Act authorized the US Department of Homeland Security to access library patron records in their search for terrorists, many librarians started using software that deleted a patron’s record once a book was returned. Products that violate people’s privacy and discriminate against them go against my professional ethos, and it’s deeply concerning to see such products eagerly adopted by institutions of higher education.

This zealousness would be slightly more understandable if there was any evidence that these programs actually did what they claim. To my knowledge, there isn’t a single peer-reviewed or controlled study that shows proctoring software effectively detects or prevents cheating. Given that universities pride themselves on making evidence-based decisions, this is a glaring oversight.

Fortunately, there are movements underway to ban proctoring software and ban face recognition technologies on campuses, as well as congressional bills to ban the US federal government from using face recognition. But even if face recognition technology were banned, proctoring software could still exist as a program that tracks the movements of students’ eyes and bodies. While that might be less racist, it would still discriminate against people with disabilities, breastfeeding parents, and people who are neuroatypical. These products can’t be reformed; they should be abandoned.

Cheating is not the threat to society that test proctoring companies would have you believe. It doesn’t dilute the value of degrees or degrade institutional reputations, and student’s aren’t trying to cheat their way into being your surgeon. Technology didn’t invent the conditions for cheating and it won’t be what stops it. The best thing we in higher education can do is to start with the radical idea of trusting students. Let’s choose compassion over surveillance.

Shea Swauger is an academic librarian and researcher at the University of Colorado Denver.



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5 Reasons Why You Should Buy The New Maruti Suzuki S-Cross 2020

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Ever since Maruti Suzuki discontinued diesel engines, its SUV S-Cross went off the sales chart as it only had a diesel variant. However, the 2020 Maruti Suzuki S-Cross is back with a powerful new hybrid petrol engine and better looks.

As reported in our previous article, the bookings for SUV are already open and you can book it from the nearest Nexa outlet or through online platforms. However, at that time we knew very little about the specifications of the new S-Cross. As the automaker confirms the details of the SUV, we can say the new S-Cross is quite impressive.

In fact, this SUV is worth considering before buying a new car in the compact SUV segment. Here are the reasons why we think you should check out the all-new 2020 Maruti Suzuki S-Cross.

5 Reasons Why Maruti Suzuki S-Cross

Image: Maruti Suzuki

1. Improved Built Quality And Safety Standards

Unlike the reputation of the automaker for built quality, Maruti Suzuki S-Cross is quite impressive with its high-end safety standards. The SUV has a five-star safety rating in ASEAN NCAP crash test.

With an overall score of 15.48 out of 16 for adult occupant protection, S-Cross is one of the safest cars in its segment.

Poor safety standards are one of the major reasons why people switch away from Maruti cars. With this assurance, you can go for S-Cross without any hesitation.

2. Hybrid Powertrain

maruti suzuki s-cross hybrid powertrain
Image: Maruti Suzuki

The new Maruti Suzuki S-Cross is one of the most affordable SUVs with a hybrid powertrain. The latest variant of this compact SUV is equipped with Suzuki’s Smart Hybrid Vehicle Technology (SHVS).

Under the hood is a combination of a K15B 1.5-liter BS6 compliant petrol engine and an electric motor. The electric motor gets power from two small lithium-ion battery packs.

With this powertrain, the SUV gets a total output of 103 BHP and 138 Nm of peak torque. The engine is available with both manual and automatic transmission.

Not only does the S-Cross have decent power delivery, but it also has very low carbon emissions due to the hybrid powertrain. Maruti Suzuki S-Cross is a very good option for masses who prefer eco-friendly cars.

Apart from this, Maruti Suzuki has provided features like Idle Start-Stop (ISS), Brake Energy Regeneration, and Torque assist during acceleration for a better experience.

3. Impressive Mileage

Being an SUV, S-Cross has quite an impressive fuel- efficiency. The automaker claims to provide a mileage of 18.55 km/l on MT and 18.43 km/l with AT. Generally, the SUVs in this segment offer a fuel-economy of under 15 km/l. However, with a mild-hybrid and idle Start-Stop (ISS) system, Maruti Suzuki S-Cross is providing impressive mileage.

The idle start-stop system turns off the engine when the vehicle is stationary, especially when waiting at red lights, and starts it again when the clutch is pressed. This way, it cuts off unnecessary fuel-consumption.

Looking at the fuel-efficiency we can say now you don’t have to worry about fuel-economy.

4. Improved Braking And Ride Quality

s-cross disc brakes
Image: Maruti Suzuki

The new S-Cross comes with 4 disc brakes, which provides amazing stopping power, you can easily go into a corner with a higher speed without any worry. Well, it doesn’t mean you should over-speed, always ride within the safe speed limit.

The front disc brakes of S-Cross are ventilated for better heat dissipation. The braking force acts more on the front wheels, therefore the front wheels need to be better in all aspects than the rear one.

5. More Features, More Comfort

s-cross features
Image: Maruti Suzuki

The 2020 Maruti Suzuki S-Cross features a smart infotainment system with Android Auto and Apple CarPlay connectivity. Additionally, this compact SUV is equipped with features like cruise control, autosensing rain wipers, push start, and much more.

Other than this, the rear seats of the car are made foldable that allows the user to have more cabin space. Foldable seats are very useful in putting extra luggage.

The best part is that, with all these features and a hybrid tag, the price of S-Cross starts at Rs 8.39 lakh (ex-showroom). On the other hand, there are no hybrid SUVs in this segment except the MG Hector hybrid which is almost twice in price than S-Cross. This also makes S-Cross a value for money car.

Finally, we would like to say that though it might not be the best selling car of Maruti, it’s much better than the other best selling cars of the company.

Do share your views in the comments section below.

The post 5 Reasons Why You Should Buy The New Maruti Suzuki S-Cross 2020 appeared first on Fossbytes.



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