When attempting to install a new package or update an existing package if you are presented with the error E: Release file expired, ignoring http://archive.debian.org/debian-archive/debian/dists/squeeze-lts/Release (invalid since 189d 0h 42min 32s) You will need to execute the following command as root: $ echo ‘Acquire::Check-Valid-Until “false”;’ > /etc/apt/apt.conf.d/90ignore-release-date And then perform… Read more…
For a well described tutorial on basic PHP profiling and optimization I would recommend the 3 part article written by Davey Shafik: Profiling PHP Part 1: Intro to Xhprof & Xhgui Profiling PHP Part 2: Xhgui In-Depth Profiling PHP Part 3: Practical Performance Tuning
Key Generation ssh-keygen -q -f ~/.ssh/id_rsa -t rsa Enter passphrase (empty for no passphrase): … Enter same passphrase again: … Key Distribution # first, upload public key from client to server scp ~/.ssh/id_rsa.pub user@server.example.org: # next, setup the public key on server cat ~/id_rsa.pub >> ~/.ssh/authorized_keys chmod 600 ~/.ssh/authorized_keys rm Read more…
Breaks down structure of matter into atoms and, by use of conventional symbols, shows the action of electrons within an atom. The principles involved in the flow of current are explained and a volt, ampere and Ohm are defined. full details…
Basic Ocilliscope Tutorial Definately the best tutorial on the basic control and use of a dual channel ocilliscope.