byronc bits

udiskie

Thu, 03 Jun 2010 20:55:02 MDT

With the deprecation of HAL proceeding at full speed it's time to find a new solution for automounting disks on my Linux box. I've been happily using halevt, which does a lot more than disk mounting, but won't be of much use once HAL really goes away. udisks is the replacement that the major desktops are moving to, so I decided to write a simple automounting daemon for those of us not using a major desktop: udiskie. It's a simple udisks client that just takes care of mounting removable media right now. I run it by adding udiskie & to ~/.xinitrc. When I'm done using a removable disk, udiskie-umount will take care of the unmount. I probably can't stress enough how simplistic and undocumented this approach is, but it works for me.

And, of course, for the Archlinux users, it's already packaged in the AUR: udiskie

pm-utils and Locked Screens

Tue, 06 Apr 2010 05:54:54 MDT

pm-utils seems to be the clear winner to userspace suspend and hibernate setup. It's a great back, but, for those of us who don't run a desktop environment with a power manager, there's one thing missing: screen locking. I'd like the screen to be locked when my computer resumes from either suspend or hibernate, and I don't want to run gnome-power-manager to get that functionality. So, 00lock-screen to the rescue. Just drop that file in /etc/pm/sleep.d and, as long as you have xscreensaver, gnome-screensaver, i3lock, or xlock setup, the screen will lock as your computer suspends or hibernates.

For the Archlinux users, it's already packaged in the AUR: pm-utils-screen-lock

OpenWRT on the D-Link DIR-615

Wed, 10 Mar 2010 06:41:01 MST

Last night, I finally got around to installing the OpenWRT 10.03 Beta on my D-Link DIR-615. The short version: it works and works well. There were only two surprises I ran into.

The first surprise is that the wireless drivers are not included in the install image. Running opkg update; opkg install kmod-ath9k takes care of that. The drivers are left out by design at least on this router and the WRT160NL. Bonus points to OpenWRT for allowing me to file a bug without creating an account on their bug tracker.

The second surprise is that the dynamic dns client doesn't know about DNS-O-Matic. I installed the ddns-scripts package and used the following config to get it working:

config 'service' 'myddns'
	option 'ip_source' 'network'
	option 'ip_network' 'wan'
	option 'check_unit' 'minutes'
	option 'enabled' '1'
	option 'domain' 'all.dnsomatic.com'
	option 'username' 'username'
	option 'password' 'password'
	option 'update_url' 'http://[USERNAME]:[PASSWORD]@updates.dnsomatic.com/nic/update?hostname=[DOMAIN]&myip=[IP]'
	option 'check_interval' '5'
	option 'force_interval' '480'
	option 'force_unit' 'hours'

gdb and pthread

Fri, 19 Feb 2010 21:33:22 MST

Error message translation time. Here's an error gdb gave me today:

[Thread debugging using libthread_db enabled]             
Cannot find new threads: generic error

Translation: Programs that use pthread functions should really be linked with the -lpthread option.

Scripting wireshark with lua

Wed, 09 Dec 2009 06:44:23 MST

While attempting to wrap some wireshark processing with a bash script, I discovered that I didn't need to write complex bash code at all, because wireshark has a built-in scripting language. Even better, it's a common scripting language: lua. It looks like Debian and its derivatives ship wireshark with lua support, but for everything else, you'll have to rebuild the package to enable it. There's a great page of examples and the api is really simple. And for those cases where you don't want to use the wireshark GUI, lua scripts work just fine with tshark.

If lua is overkill for the task at hand, tshark also offers decent control over what shows up in the output. If you want to see all HTTP requests and their request URI and method, without any other information about the packet, this tshark command will do the trick:

tshark -T fields -e http.request.method -e http.request.uri -R 'http'

gnome-screensaver and alternative window managers

Tue, 30 Jun 2009 22:15:18 MDT

I've been using gnome-screensaver with awesome for a while without any problems. Unfortunately that all came to an end when GNOME 2.26 hit Debian Sid last week. Just so that no-one else has to dig for this, gnome-screensaver now uses gnome-session to determine idle time. gnome-screensaver will run without gnome-session, but the screensaver and locking mechanism will never kick in. Fortunately, there is an easy fix. I changed my

gnome-power-manager &

line to

gnome-session &

in ~/.xsession and everything works now.

pcapy

Thu, 21 May 2009 09:21:35 MDT

So, pcapy is a great, simple library to interface with libpcap. It works well for reading live packets and dump files. There's only one problem: there is no way to modify or create a struct pcap_header from Python code. So there's really no way to add data to the packets and add them to a dump file.

View a Certificate

Wed, 20 May 2009 11:10:40 MDT

Yet another command I'll never remember unless I write it down. Here's how to view a certificate. In my case I was viewing a certificate that Mutt had stored:

openssl x509 -in .mutt_certs -noout -text

_hg_ps1()

Tue, 31 Mar 2009 21:23:53 MDT

In honor of the decision to move Python development to Mercurial, I decided to write something helpful. I've found __git_ps1() to be incredibly useful, so, here's my take on _hg_ps1():

_hg_root()
{
    local basedir=$(pwd)

    while [ '/' != "${basedir}" ]; do
        if [ -d "${basedir}/.hg" ]; then
            break;
        fi

        basedir="$(readlink -f "${basedir}/..")"
    done

    [ '/' == "${basedir}" ] || echo -n "${basedir}"
}

_hg_ps1()
{
    local g=$(_hg_root)
    if [ -n "${g}" ]; then
        local branch

        branch=$(hg branch)
        if [ -f "${g}/.hg/bookmarks.current" ]; then
            branch="$(< "${g}/.hg/bookmarks.current"):${branch}"
        fi

        if [ -n "${1-}" ]; then
            printf "$1" "${branch}"
        else
            printf " (%s)" "${branch}"
        fi
    fi
}

Yes, I know that the hg root command does the same thing as my _hg_root(), but it felt slow running mercurial before printing each prompt. The only thing that's missing is showing when merges are in progress. I'll try to add that the next time I need to do a manual merge.

Update: It seems that some of my repositories don't have a .hg/branch file so I'm calling hg branch for that info. Also, the readlink line in _hg_root() did not properly handle spaces.

Saving ViM Macros

Wed, 11 Mar 2009 09:32:01 MDT

I use ViM macros (aka complex-repeat) all the time. Occasionally, I find that it would be nice to reuse one of my macros across editing sessions. Turns out it's pretty easy to save the macro. Just add a line like the following to a file that gets sourced when your file is opened by ViM (This example is from ~/.vim/ftplugin/rst.vim).

let @h = "yypVr"

Now, whenever I open a ReStructured Text file, I can hit @h and my macro will run.