To flash a LED we will use the GPIO pins(general purpose input/output) to control the LED. We will control these GPIO pins using Python. The GPIO layout on the Raspberry Pi model B. We will be using GPIO 17 which is Pin 11. 1. Installing the library for python. $ sudo apt-get install python-dev python-rpi.gpio […]
Linux
How to burn an ISO to CD or DVD using Wodim
Wodim is a command line tool for burning ISO files to disks. wodim is used to record data or audio Compact Discs on an Orange Book CD-Recorder or to write DVD media on a DVD-Recorder. Step 1 Locate you CD/DVD writer. # wodim –devices Example output: # wodim –devices wodim: Overview of accessible drives (1 […]
CentOS/RHEL: /tmp mount point not automatically mounting when added in /etc/fstab
Problem /tmp is not automatically mounted after reboot even though an entry is present in /etc/fstab. Below outputs show an example of the issue: # uptime 16:44:11 up 2 min, 1 user, load average: 0.21, 0.55, 0.44 # df -h Filesystem Size Used Avail Use% Mounted on devtmpfs 252G 0 252G 0% /dev tmpfs 252G […]
“No space left on device” – kdump generation issue (CentOS/RHEL)
The Problem Unable to generate kdump and fails with the following error: Checking for memory holes : [100.0 %] | copy_bitmap_file: Can’t write the bitmap(/tmp/kdump_bitmapQijuck). No space left on device” kdump: dump target is /dev/[ 14.793505] EXT4-fs (dm-0): re-mounted. Opts: (null) mapper/VGExaDb-kdump_vol kdump: saving to /kdumproot/kdump/u01/crashfiles/127.0.0.1-2020-04-29-09:46:31/ kdump: saving vmcore-dmesg.txt kdump: saving vmcore-dmesg.txt complete kdump: saving […]
How to monitor your CPU on debian or ubuntu systems
There are many reasons to want to monitor your CPU maybe if you are over-clocking(making sure your CPU hasn’t caught fire after running Prime95), or you might just be interested to look at your CPU temps, there are lots of different reasons and this is a post to show you how. For both of these […]
How to fix the “Firefox already running” problem on Linux
After creating a script that included closing a firefox tab and hiding the window I realized I could not open firefox and just got a “Firefox is already running” error every time after running this script once. I tried running the command: $ sudo killall firefox As there may have been some hidden windows however […]
How to create a Python Dictionary
Dictionaries in python are quite similar to arrays in how they look however arrays are indexed by a range of numbers i.e. 1-10, but dictionaries are indexed by their key. You can set these keys to immutable data types only. They can also be known as key pair arrays. You will be used to seeing […]
Command line parameters in shell scripts
Command line parameters are a way to pass information into a program or script in order for it to do what you want it to. Some examples of command line parameters: $ ls -l $ cat textfile The command line parameters here are the “-l” and “textfile”. How are command line parameters accessed within a […]
How to format code within web pages
When displaying code within web pages it can be hard to read if it hasn’t been separated from the other text and images on the page. To get around this problem you can use google code-prettify JavaScript. This allows code to be displayed like this: To implement this within your HTML you need to add […]
How to Enable sudo I/O Logging
sudo will normally only log the command it explicitly runs. If a user runs a command such as sudo su or sudo sh, subsequent commands run from that shell are not subject to sudo’s security policy. The same is true for commands that offer shell escapes (including most editors). If I/O logging is enabled, subsequent […]