Sudo and shell redirection One of our students was stuck using sudo to change a file. This spawned a lengthy email discussion on how the shell works and what sudo actually does. Here is the crux of the problem: This works: $ sudo touch /etc/aaaa This does not: $ sudo echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governer And here is my response: The [...]

CS@VT Open House Last week the computer science department had an open house day where everyone showed their research to the rest of the university. I was on vacation but one of the SCAPE lab students was on hand to show our stuff.

Email gone Yesterday I realised I was missing some email from when I started working at VT. I asked support what was up and they revealed the horrific truth: Matthew, The current policy for IMAP is that your e-mail will be deleted after 32 days with no recovery mechanism, unless you take action by [...]

Compiling a kernel the Redhat way One of our students was having trouble making a custom kernel for our test cluster. I wrote him a howto for making Kernel RPMs. Unpack the kernel: cp linux-2.6.38.tar.bz2 /usr/src/ cd /usr/src/ bzip2 -d linux-2.6.38.tar.bz2 tar -xf linux-2.6.38.tar ln -s linux-2.6.38 linux cd linux-2.6.38 Copy old config: cp /boot/config-2.6.25-14.fc9.x86_64 .config make [...]

Powerpack in the flesh One of the things the SCAPE lab is famous for is Powerpack. This is a software hardware solution for fine-grained monitoring the power consumption computers. Rather than just a machines total consumption at the wall you can see how much electricity the hard drive / CPU / memory etc use [...]