Daemon Dancing

Monday, August 18, 2008

Yet Another Backup Solution

In these days of US$150 1 terabyte hard drives, there is simply no reason not to have multiple hard drives and implementing a regular backup plan. Of course, I don't have one and feel like I'm walking the high wire without a net. I've installed a couple of GUI rsync frontends, but haven't done anything with them. I even did some work to try and update dar to work, given its orphaned status (although they finally updated it in the openSUSE repositories), but still haven't done anything. Here's another tool that looks easy to use, although I really think I should set up a real bacula setup for all the home computers.

BackupGem Manual

Backup is the easiest and most flexible backup, archive and rotate tool. It’s a beginning-to-end solution for scheduled backups in a clean ruby package that is simple use and powerful when customized.

Monday, August 4, 2008

Back in the Saddle

As you may have noticed (for both of my readers), I am back to updating Daemon Dancing instead of helping out at Linux Brain Dump, as LBD seems to have slipped into a funk lately. So I figured I would just go back to working on Daemon and trying to update the look and feel of it. But I had forgotten just what an incredible time sink it can be once you begin playing with your blog look! Just a few minor tweaks (like trying to get the search box to work) took a couple of hours, as I played with all kinds of settings. And, as you can probably see, this is a pretty plain vanilla Movable Type blog!

Anyway, look for more Linux, FreeBSD and other FOSS software ramblings to show up here again.

Just a quick note on FreeBSD - while I don't run it on my home desktop, my server (the one that hosts this blog, for instance), runs FreeBSD 6.1 (a little out of date). I finally bit the bullet and did a full package upgrade and lo and behold, it went like a champ, despite the long delay between updates. At least I had the portsnap cron job running, so that part was kept up to date. The first portsnap update command took a very long time, but after a few carefully chosen upgrades, I just jumped in with both feet and the portmanager -u command did it all. Of course, I haven't tried rebooting yet, which is the real test. But still, very nice.

Friday, August 1, 2008

AIRing it out

Very nice intro to AIR on Linux found at Linux Journal. AIR (Adobe Integrated Runtime) is Adobes push for a crossplatform rich Internet app "operating system". I've been using it for Twhirl, a very nice Twitter client. For some reason, there are many Twitter clients using AIR. Adobe claims AIR to be only in an "alpha" state for Linux, but it has been working for me pretty well.

The only obvious shortcoming is that, according to the Twhirl author, the Linux version doesn't support the password encryption that is found on the Windows client, so it doesn't store passwords. And there are some rough edges for the UI, like the super-annoying Mac-like restriction of only resizing the window via dragging the lower right corner. And the auto-update feature doesn't work. You have to download the update file for the app and install it yourself. But it has been very stable for me and I'd like to look more into programming with it.

An Introduction to AIR

Vee Dee Eyes page

Cool page providing a bunch of VDIs, which are images you can use in VirtualBox, my current favorite OS emulator. These VDIs are pre-installed OS images that run in VirtualBox and let you quickly try out any OS (mostly Linux, of course).

Sun xVM VirtualBox VDI Index | veeDee-Eyes

The VirtualBox "Virtual Disk Image" Index
VDI images of pre-installed "Open Source" Operating System distros.
It's a computer inside your computer.

Wednesday, July 30, 2008

Teaching OSS to Share

Say you're doing some programming, or trying out an older audio program, and you get some form of the following cryptic error:

unable to open `/dev/dsp', Device or resource busy

What does it mean and what can you do about it?

As to what it means - basically, an application somewhere isn't being very nice and sharing, like we have all be taught to do. Or it wants to hog the sound device all to itself and another app won't let it go. /dev/dsp is the device pointer for the default "dsp" or digital sound processor and, as audio remains a bit of an Achilles heel for Linux, there can be problems in the sandbox.

So what you need to do is to figure out which app currently has locked, so maybe you can quit that application to allow our other one to access it. You might think of using lsof or fuser to figure it out. So you check:

$ lsof /dev/dsp
$ fuser /dev/dsp

But unfortunately, it won't show you anything. I think this is because /dev/dsp is just an affectation, which allows Linux to point wherever it really wants to.

In this case, it is the /dev/snd/* files. It is here you want to see who is grabbing things:

$ ls /dev/snd
controlC0  hwC0D2    pcmC0D0p  pcmC0D1p  pcmC1D0c  seq
controlC1  pcmC0D0c  pcmC0D1c  pcmC0D2c  pcmC1D0p  timer
$ lsof /dev/snd/*
COMMAND    PID     USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
VirtualBo 4083 jdarnold  mem    CHR 116,10          4395 /dev/snd/pcmC0D0c
VirtualBo 4083 jdarnold  mem    CHR  116,9          4390 /dev/snd/pcmC0D0p
VirtualBo 4083 jdarnold   40r   CHR  116,2      0t0 4102 /dev/snd/timer
VirtualBo 4083 jdarnold   42u   CHR 116,10      0t0 4395 /dev/snd/pcmC0D0c
VirtualBo 4083 jdarnold   43u   CHR 116,12      0t0 4411 /dev/snd/controlC0
VirtualBo 4083 jdarnold   44r   CHR  116,2      0t0 4102 /dev/snd/timer
VirtualBo 4083 jdarnold   45u   CHR  116,9      0t0 4390 /dev/snd/pcmC0D0p
VirtualBo 4083 jdarnold   46u   CHR 116,12      0t0 4411 /dev/snd/controlC0
kmix      4155 jdarnold   12u   CHR 116,12      0t0 4411 /dev/snd/controlC0
kmix      4155 jdarnold   13u   CHR  116,5      0t0 4560 /dev/snd/controlC1
$ fuser /dev/snd/*
/dev/snd/controlC0:   4155  4800
/dev/snd/controlC1:   4155
/dev/snd/pcmC0D0c:    4800m
/dev/snd/pcmC0D0p:    4800m
/dev/snd/timer:       4800
$ ps -c 4800
PID CLS PRI TTY      STAT   TIME COMMAND
4800 TS   19 ?        SLl    0:12 /usr/lib/virtualbox/VirtualBox -comment Debia

Pretty conclusive proof that it is VirtualBox using the device. So let's see what it looks like after I quit out of VirtualBox:

$ lsof /dev/snd/*
COMMAND  PID     USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
kmix    4155 jdarnold   12u   CHR 116,12      0t0 4411 /dev/snd/controlC0
kmix    4155 jdarnold   13u   CHR  116,5      0t0 4560 /dev/snd/controlC1
$ fuser /dev/snd/*
/dev/snd/controlC0:   4155
/dev/snd/controlC1:   4155
$ ps -c 4155
PID CLS PRI TTY      STAT   TIME COMMAND
4155 TS   19 ?        S      0:00 kmix [kdeinit] -autostart

kmix, the KDE sound mixer program, is pretty good about things, and thus we no longer have a conflict:

$ ./dspinfo
Information on /dev/dsp:

Defaults:
sampling rate: 8000 Hz
channels: 1
sample size: 8 bits
block size: 1023 bytes

Supported Formats:
mu-law
unsigned 8-bit (default)
signed 16-bit little-endian
signed 16-bit big-endian
signed 8-bit
unsigned 16-bit little-endian
unsigned 16-bit big-endian

Capabilities:
revision: 1
full duplex: yes
real-time: yes
batch: no
coprocessor: no
trigger: yes
mmap: yes

Modes and Limits:
Device    Sample    Minimum   Maximum
Channels  Size      Rate      Rate
--------  --------  --------  --------
1         8      1000    100000
1        16      1000    100000
2         8      1000    100000
2        16      1000    100000

dspinfo is a small program I adapted from the exerpt for the old O'Reilly book Linux Multimedia Guide, which is Chapter 14. Programming Sound Devices. As I said, OSS (Open Sound System) is an old Linux standard, pretty much passed by in these days of 2.6 kernels.

Thursday, January 17, 2008

Linux HowTo search

A page using a focused Google search to look for just the right HowTo to scratch that itch:

HowtoFinder - The search engine for Howto's and Tutorials