A Simple Python script to blink a Raspberry Pi LED.
import RPi.GPIO as GPIO
from time import sleep
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BOARD) # Uses the physical pin numbering
GPIO.setup(7, initial=GPIO.LOW) # Set GPIO pin to off
while True:
GPIO.output(7, GPIO.HIGH)
sleep(0.2)
GPIO.output(7, GPIO.LOW)
sleep(0.2)
Change pin numbers as needed.
We can also do this with BASH.
You will need an Android Terminal. You can turn on the default one in the developer settings. Need to turn on developer mode?
You will also need to enable root which can also be done in the Developer settings
Open up the terminal app and run
su
rpi3-audio-jack.sh
More info here
Download LineageOS
Download the unofficial LineageOS 16 build from the following page
https://konstakang.com/devices/rpi3/LineageOS16.0/
Unzip
Unzip the file with
unzip ~/Downloads/lineage-16.0-20200207-UNOFFICIAL-KonstaKANG-rpi3.zip
Write to SD Card
Either use the instructions on the following link to write it to the SD card
https://www.raspberrypi.org/documentation/installation/installing-images/windows.md
Or use DD
WARNING! Make sure “/dev/mmcblk0” is the correct SD Card. Refer to here if you need to locate the path for the SD Card.
sudo dd if=~/Downloads/lineage-16.0-20200207-UNOFFICIAL-KonstaKANG-rpi3.img of=/dev/mmcblk0 bs=1M status=progress
Plug you SD Card into your Pi and boot it up.
The following script is for monitoring if an IP address is reachable or not. If it becomes unavailable the script will turn on a LED that is plugged into one of the GPIO pins of the Raspberry Pi. View pinout here
Script
#!/bin/bash
# Script to ping ip address and turn on LED on if device is unreachable.
nPin="18" # Change if GPIO pin is different
ledPin="gpio${nPin}" toPing="8.8.8.8" # Change to address you want to ping
echo "${nPin}" > /sys/class/gpio/export
echo "out" > /sys/class/gpio/${ledPin}/direction
if ( fping -r1 $toPing | grep -v alive ); then
echo "Internet unreachable"
# Turn on LED
echo "1" > /sys/class/gpio/${ledPin}/value
else
# Turn off LED
echo "0" > /sys/class/gpio/${ledPin}/value
fi
Save script as ping_led.sh and make it executable.
chmod +x ping_led.sh
and run the script.
sh ping_led.sh
Run script in crontab
You can setup the script to run every minute using a crontab
crontab -e
Add the following line
*/1 * * * * /home/pi/ping_led.sh
Should now execute the script every minute and not need any human interaction.
Helpful image from the Raspberry Pi site.
Note the numbers are the GPIO nmumbers you would use for programming.
Some helpful links
https://www.raspberrypi.org/documentation/usage/gpio/
https://pinout.xyz/
https://www.jameco.com/Jameco/workshop/circuitnotes/raspberry-pi-circuit-note.html
Slackcat allows you to send Slack messages from the Linux command line.
Update pi
sudo apt-get update
Install Ruby and other components
sudo apt-get install ruby1.9.1 ruby ruby-dev rubygems
Install Slackcat
sudo gem install slackcat
Use Slackcat. You will need to generate an API Key from Slacks website.
echo "Hello World" | slackcat -k API-KEY -p --channels=#CHANNEL_NAME
Examples :
Send to Channel
echo "Hello World" | slackcat -k xoxp-94827839414-94819543146-441447827184-h7dt2hg2h8ggs7d24ce638edrw9q8def -p --channels=#General
Send Direct Message
echo "Hello World" | slackcat -k xoxp-94827839414-94819543146-441447827184-h7dt2hg2h8ggs7d24ce638edrw9q8def -p --users=#General
This is on a Raspberry Pi, but should be the same on any Linux distro.
Error :
pi@raspberrypi:~ $ mail Cannot open mailbox /var/mail/pi: Permission denied No mail for pi pi@raspberrypi:~ $
Fix :
sudo touch /var/mail/$USER sudo chown $USER:mail /var/mail/$USER sudo chmod 660 /var/mail/$USER
You can replace “$USER” if you need to run the commands for a different account.
Example:
sudo touch /var/mail/pi sudo chown pi:mail /var/mail/pi sudo chmod 660 /var/mail/pi
The examples given here are for modifying the wlan0 interface. Replace wlan0 with the interface you are configuring. i.e. (eth0,wlan1)
Method 1
This was the typical way to add a static IP address to a Pi, if you have issues with this, then try Method 2.
sudo vi /etc/network/interfaces
In the file it is pretty easy to see which lines control which interface, find the lines that control wlan0 (or the interface your configuring) and change/add to look like below.
iface wlan0 inet static address 192.168.42.109 netmask 255.255.255.0 gateway 192.168.42.1
Save the file, reboot, and the Pi should come up with the new static IP.
Method 2
It looks like on the newer versions of Raspbian, the above method does not work anymore, so now you have to edit the following file
sudo vi /etc/dhcpcd.conf
and add the following lines.
interface wlan0 static ip_address=192.168.42.109/24 static routers=192.168.42.1 static domain_name_servers=192.168.42.1
If you just need to assign a static IP address, to the device, because it is going to be setup as a hotspot or something, you can get away with the following.
interface wlan0 static ip_address=192.168.42.1/24
If you run into issues with it not assigning the address, check the /etc/network/interfaces file and make sure that the line that starts with “iface wlan0” says manual at the end and not static. If it says “iface wlan0 inet static”, change it to “iface wlan0 inet manual”
Replace “4” with the GPIO pin your using.
echo "4" > /sys/class/gpio/export
Setup the direction. If it was a button or switch we would change “out” to “in”.
echo "out" > /sys/class/gpio/gpio4/direction
Turn the LED on.
echo "1" > /sys/class/gpio/gpio4/value
Turn the LED off.
echo "0" > /sys/class/gpio/gpio4/value
1 = on and 0 = off.
Debian Based Distros
The below command should work for Debain, Ubuntu, and the Raspberry Pi Raspbian.
dpkg --get-selections
RPM Based Distros
The following works on Fedora, CentOS, ReHat.
rpm -qa
The above commands return all of the packages installed on a system. If you want to look for a specific program or package you can use grep to filter the results.
rpm -qa | grep program
or
dpkg --get-selections | grep program