Grub2 is the new bootloader for Red Hat and Centos 7. Grub 1 (grub legacy) used on older Red Hat and Centos releases was really simple. Just edit grub.conf and you were done.
Grub2 however seems really complex. Maybe it is just new material that you must getting used to.
Lets change the boot delay in grub2. Continue reading
Howto: log webcrawlers, robots, indexers and other useless user-agents to a different logfile.
I collected a big list of user-agents which I do not want to be logged to the apache webserver logfile. I prefer them to be logged to a different logfile.
This is an online random number generator for a MSP430 microcontroller, you can use it to include some randomness in your project.
When using these static random numbers in more than one MSP430 controller, they all got the same random numbers, however all oscillators differ somewhat in speed over time and thus multiple MSP430 controllers using the same random number table do really seem random.
After the random timer based on an Attiny24 I have build a larger version of the random countdown timer. The Attiny24 had a single channel and two potentiometers. In this countdown timer the number of outputs have been increased from 1 to 8. The potentiometers have been replaced by a 2×16 HD44780 LCD screen and a rotary encoder.
With this random countdown timer circuit you can turn on and off 8 outputs. The outputs are, while randomly turned on and off, still grouped together meaning that as a group that at the beginning and half way the countdown timer cycle they are all on or off at the same time.
With this circuit you can simulate people turning on and off internal house lighting in a street on a model railroad track. Read on and see it in action.
What is a time server? A time server gets its time from a reference time source. That source can be a another time server, a local time source such as a rubidium or cesium atomic clock. In this post I make an USB GPS receiver for a Linux time server using cheap available components. After assembling the GPS module I give instructions on how to configure the Linux NTP daemon to use this module. The GPS receiver gets its time signal from the GPS satellite network. Its longtime time drift is about 0 seconds. This is possible because the GPS time signals are constantly adjusted to keep very accurate time needed for navigation.
Here I present to you a single AA battery led circuit. This circuit is a variant of the Joule thief in that it contains 2 transistors and a simple standard 2 lead inductor instead of a hand wound 2 wire inductor.
You can use it as a white led torch. You can use a fresh AA battery, but the circuit is special in that it accepts empty batteries. Down to 0.7 volts. Do you have a box of empty batteries? They are still useful to power this led circuit. Continue reading
This howto shows you the schematic of a popular TDA2030A amplifier DIY kit which is sold on eBay and other places.
After ordering the kit on eBay (search for “TDA2030A Audio Power Amplifier DIY Kit”) I received a version 1.0 PCB made by XY HI-FI with components and a short Chinese manual on what was needed to solder the kit in stereo mode (OCL) or in mono mode (BTL or bridge). Continue reading
This is an online random number generator for an AVR microcontroller, you can use it to include some randomness in your project.
When using these static random numbers in more than one AVR controller, they all got the same random numbers, however all oscillators differ somewhat in speed over time and thus multiple AVR controllers using the same random number table do really seem random. The effect is the biggest when using the internal RC oscillator because from AVR to AVR the speed differs the most. Continue reading
I made an update for the e2fsprogs rpm for Centos that enables ext4 online defragmentation using e4defrag.
The Ext4 file system supports online defragmentation since kernel version 2.6.28. Centos 6 has version 2.6.32 but does not include the e4defrag utility to defragment ext4 files. Centos 6 has version 1.41 of the e2fsprogs. Version 1.42 or newer provides e4defrag. Continue reading
I have compiled for you a PHP-FPM Centos 6 rpm that can be installed for PHP 5.3.3-14. This rpm works with the standard PHP version that is installed with Centos 6. With this you can configure Apache to use fastcgi and this opens the possibility to use Apache worker MPM.
Why? PHP-FPM offloads php scripts to a dedicated daemon freeing up precious memory and processing power in Apache making it faster.