linux

Sun Java on Debian/Ubuntu

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It would appear that even if you install ONLY the sun java package it
drags in some GNU java stuff as well.

You can go through everything in /etc/alternatives and update it
manually but that is somewhat time consuming.

Instead just run:

sudo /usr/sbin/update-java-alternatives --set java-1.5.0-sun

and this will sort everything :)

Dropbox

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Somone appears to have created a online storage and sync thing that actually works:

Dropbox - Home - Secure backup, sync and sharing made easy.

Few grips thou:

  • It requires nautilus
  • Not obvious how to create an account (it's not on the website, the client does it)
  • The initial dialog box (which you use to sign up for an account) takes an age to appear

All that aside it works wonderfully, copy file into ~/Dropbox and it syncs automatically :)

... oh and it versions files too
... and only sends binary diffs

Another blog added

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Another one I've just added to my feedlist,

http://blog.kovyrin.net/

some interesting stuff, especially on the MySQL front.

He is also the author of the MySQL Master-Master Replication Manager
which can be found here:

http://code.google.com/p/mysql-master-master/

definitely something I'll be looking at.

XMLStarlet

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I'm not the greatest fan of XML for much the same reasons as Jeff Atwood who wrote a controversial blog post on the subject.

Sometimes though I'm forced to deal with it. XMLStarlet looks like it might relieve some of my frustration.

Thanks to BASH Cures Cancer for flagging this.

Log Levels

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As a sysadmin I spend much of my day trawling though log files looking for problems.
Unfortunately many developers don't appear to know how to use log levels effectively which can make a sysadmin's life a small hell when it comes to debugging.

As a general rule I advise the following:

Be quiet about successful operations and verbose about unsuccessful ones.

Yes I like to see what an application is doing but I don't need to know every function call that it's making, yes this is useful when developing an application but can make isolating a problem in production a real pain.

Generally I use 4 different log levels:

  • DEBUG
  • INFO
  • WARN
  • ERROR
    • The definitions for these go something as follows:

      DEBUG Things that should happen but you don't want to see in production. This includes function tracing, SQL statements, variable values etc...
      INFO Things that should happen that give you just enough idea about what's going on. This should be limited to 1 or 2 lines per transaction,
      WARN Things that shouldn't happen but the end user should see no difference. For example $foo failed so falling back to $bar instead
      ERROR Houston we have a problem! This is a serious error that has caused a problem for the end user. If you want to dump variables to the logs then now is a good time to do it.

      Some applications do logging in a completely different way, they have more log levels. Generally in production you want to know just enough to know what the application is doing + all the warnings and errors.

      If something goes wrong then you need enough information to be able to replicate it. If all is well then, as sysadmins, we don't care.

MySQL 5.1 on Debian Etch

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Here is a quick guide to getting MySQL installed on Debian Etch without pulling
in anything from testing or unstable.

Now there are a number of different ways you could do this but I wanted a debian
package (as I have banned installing anything from source on new servers at work).

After some google action I found that Norbert Tretkowski had submitted packages to experimental
However after checking these out they wanted to pull things in from testing and/or unstable and I didn't want
that (especially considering it wanted to upgrade libc6)

That said it turned out that this package would build fine on Etch by doing the following:

Add the following to /etc/apt/sources.list:

deb http://ftp.uk.debian.org/debian/ experimental main contrib non-free
deb-src http://ftp.uk.debian.org/debian/ experimental main contrib non-free

Then create /etc/apt/preferences with the following in:

Package: *
Pin: release o=Debian,a=stable
Pin-Priority: 900
Package: *
Pin: release o=Debian
Pin-Priority: -1

which basically says "only install stuff from stable".

Next we get the dev tools and the build dependencies:

aptitude install dpkg-dev devscripts
apt-get build-dep mysql-server-5.1

Then build the .debs:

cd mysql-dfsg-5.1-5.1.24rc
debuild

Once that has finished get the run time deps:

aptitude install libdbd-mysql-perl libdbi-perl

And finally install the .debs we created earlier:

cd ..
dpkg -i *.deb

...and there you go, MySQL 5.1 on Debian Etch :)

gnome-do

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So after a mate a work started raving about Gnome Do I decided to give it another go, not quite remembering which I gave up with it last time.

Quicksilver is a program I've always installed first when using any Mac and Gnome Do is a very similar thing for Linux.

It wasn't long before I worked out why I had ditched it. I keep switching between window managers and seem to always end up back with pekwm. Launching Gnome Do in pekwm for some reason causes the "window" to end up behind all the other windows.

A quick RTFM later and I found the answer. In my ~/.pekwm/autoproperties I added:

Property = "Do,Do" {
ApplyOn = "Start New Reload"
Layer = "Menu"
Title = "^Do"
}

which forces it above all other windows.

With that sorted the only thing left is the occasional erratic behavior of the window placement, but I can live with that for now :)

irssi + screen + UTF-8

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I thought I'd sorted this once but apparently not :(

I'd managed to get things sorted so that I could input pound signs and they would appear fine to me and everyone else but if someone else typed a pound sign I got a question mark.

I *think* what was happening was that it was taking UTF-8 input and converting it to latin1... not entirely sure.

Anyway for those suffering the same issues take a look at The ultimate guide for UTF-8 in irssi and GNU/Screen

Debian 'fixes' OpenSSL

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So it would appear that Debian "fixed" a problem in OpenSSL a few years ago. Unfortunately this "fix" has meant that they have had to release this security announcement.

Now this vulnerability is quite bad, so much so that Debian have stated the following:

It is strongly recommended that all cryptographic key material which has been generated by OpenSSL versions starting with 0.9.8c-1 on Debian systems is recreated from scratch. Furthermore, all DSA keys ever used on affected Debian systems for signing or authentication purposes should be considered compromised; the Digital Signature Algorithm relies on a secret random value used during signature generation.

Ben Laurie has posted a great blog entry as to why this so stupid. This quote from that entry sums the problem up nicely:

Secondly, if you are going to fix bugs, then you should install this maxim of mine firmly in your head: never fix a bug you don’t understand.

Bash Cures Cancer

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Another site that I've just added to my feed list.

Quite a few things on here I wasn't aware of such as:

find . -name 'file-*' -delete

is much faster than

find . -name 'file-*' -exec rm {} \;

although I need to test how it compares to:

find . -name 'file-*' | xargs rm

BASH Cures Cancer

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