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Efivars and Efivarfs

Recently a new filesystem was added to the 3.8 Linux kernel and backported to the Fedora kernel-3.6.10-4.fc18 and others. Here is the scant documentation for it: efivarfs – a (U)EFI variable filesystem The efivarfs filesystem was created to address the shortcomings of using entries in sysfs to maintain EFI variables. The old sysfs EFI variables code only supported variables of up to 1024 bytes. This limitation existed in version 0.99 of the EFI specification, but was removed before any full releases. Since variables can now be larger than a single page, sysfs isn’t the best interface for this. Variables can

Fedora 18 Supports 256 Color Terminals

You may not be aware of it but currently Linux terminal emulators such as xterm only supports 8 colors while those on Apple’s OS X support 256 colors. Now, beginning with Fedora 18, Fedora will also support 256 colors via the xterm-256color terminfo database entry. To see how many colors a terminal supports: $ echo $TERM xterm-256color $ tput colors 256 I have never liked the default colors produced by the –color color option to ls and other utilities and, as a result, have normally removed such aliases from my bash startup scripts. Having 32 times more colors available gives

Software Defined Networking

We are being to enter the era of software defined networking (SDN), an emerging paradigm where network control logic (learning and forwarding decisions) is decoupled from the underlying physical network topology (routers, switches). To quote from Nick Feamster who is the Darnell-Kanal Associate Professor of Computer Science at University of Maryland: Separating a network’s control logic from the underlying physical routers and switches that forward traffic allows operators to write high-level control programs that specify the behavior of an entire network, in contrast to conventional networks, whereby network operators must codify functionality in terms of low-level device configuration. Logically centralized

IPA – Indentity Policy Audit 3.1

Identity Policy Audit (IPA) 3.1 was released in recent weeks. IPA is also known as Red Hat Enterprise Identity Management and is part of RHEL6 along with SSSD. Identify Management (IdM) describes the management of individual identifiers, their authentication, authorization, and privileges within or across system and enterprise boundaries with the goal of increasing security and productivity. If you’re not familiar with IPA, you should become familiar with it. It is basically the IdM for POSIX systems. This release is significant because it adds Active Directory (AD) trusts and Server 2012 support. You now can run an IPA Domain that

Implementing strstr in Korn Shell

Neither Bash or the Korn Shell 93 (ksh93) provide a C-like strstr builtin. Here is a simple implementation of a strstr function in ksh93. The strstr function finds the first occurrence of s2 in s1. If s2 is an empty string, 0 is returned; if s2 occurs nowhere in s1, 0 is also returned; otherwise the offset to the first character of the first occurrence of s2 is returned. #!/bin/ksh function strstr { typeset s1=”$1″ typeset s2=”$2″ if [[ ${#s2} == 0 ]] then return 0 fi typeset len=${#s1} typeset first=${s1%%${s2}*}x typeset ndx=${#first} if (( ndx > len )) then