Find how to check and tune your ext filesystem here.
How to manage root password and emergency mode in RHEL6 and RHEL7
Easiest root password management is to not set it up at all and therefore not manage it.
How to manage emergency mode without root password can be read from here.
How to set up Windows 7 with Bitlocker and Linux multiboot PC
If you have to keep Bitlocker-encrypted windows and some Linux distro safely side by side on the same PC, check out this how to. It does not matter do you want Linux to be encrypted too, both options are also described.
How to use RPi & SIM900 GSM/GPRS add-on to open the gates
If gate to your parking place opens up with a phonecall from your cellphone, bundle up with your buddies, set up RPi and save some money. Read more how to call out when you call in here.
How to use DS3231 RTC with Raspberry Pi
RTC or Real Time Clock is something what is missing on Raspberry Pi boards. Some say that its because RPi-people want to keep the price down but I tend to think that they actually want to teach you how to manage time if its not managing itself
How to use Raspberry Pi with SIM900 GSM/GPRS add-on
Feel free to check out how to run commands by calling to your RPi here.
Few commandline examples
As my head is not capable to remember everything, I started to write down useful information about the commandline tools I use. So, if you are wondering how to split video or change its framerate without re-encoding or how to jump between apt/dpkg/yum/rpm or manipulate pdf files or something else, check out this page for starters.
How to choose powered USB hub
I tried but failed. More information here. If you have had better luck tell me too.
Calculating Pi (π) with bash
I just created this post for people who ended up in this site searching for ways to get pi value with bash shell. There are multiple ways for calculation but I like following:
1. make sure you have package bc installed. It comes from package named “bc” on debian.
2. run command below where parameter scale is number of decimal places after comma.
export BC_LINE_LENGTH=0;bc -lq <<< "scale=1000;4*a(1)"
Alternatively you could make a shellscript like this:
#!/bin/bash
DP=1000
export BC_LINE_LENGTH=0
pi=`bc -lq <<< "scale=${DP};4*a(1)"`
echo ${pi}
exit 0
Environment variable BC_LINE_LENGTH with 0 value is needed to disable result line splitting with backslash and newline.
Raspberry Pi serial console connection
No network connection to your Raspberry Pi, no display, no keyboard? Seems almost like no way to connect? There is still very easy way to get into commandline trough serial port! All the instructions are here