Into.the.Void.

I’ve just updated by .zshrc so that I can get the exit status of commands on a “right prompt” using zsh’s RPROMPT variable. Exit status appears only if the value is non-zero.

Example usage:

You can find my zshrc and more dot files that I use in my Pages/My dot files

Filed by kargig at 12:32 under Linux,MacOSX
Tags: exit codes, Linux, prompt, zsh
No Comments | 13,271 views

The Task
Last year, me and comzeradd set up a Gentoo server for HELLUG according to our plot to help Gentoo conquer the world. Unfortunately Gentoo is out of HELLUG’s administration policy, all servers must be Debian. We didn’t know that, so after a small flame :), we decided that we should take back the server to somebody’s home and re-install Debian over it, the problem was that the server was located at University of Athens campus which is a bit far from downtown Athens where comzeradd lives. I also live 500km away so we were pretty much stuck. Months passed and nobody actually had enough free time to go to UOA‘s campus and take the server to their house. …In the meantime manji joined us as an extra root for the server.

One Saturday night while chatting at IRC (what else could we be doing on saturday night ??) we had an inspiration, why not install Debian remotely, without taking the server home. Even if everything got eventually borked it couldn’t get any worse than going there, taking the server home and fixing it, just like we would do any way. So we gathered on a new IRC channel with some more friends that are really good with Debian and started the conversion progress.

The Server
The interesting part about the server was that it had 2x250Gb IDE disks. The Gentoo setup had these disks partitioned to 4 software raid devices + swap partitions.
(more…)

Filed by kargig at 20:21 under Gentoo,Linux
Tags: debian, debootstrap, Gentoo, grub, HOWTO, mdadm, no psysical access, raid, raid0, raid1, remote install
11 Comments | 21,048 views

I’ve written a small perl script to parse random entries from the extremely usefull commandlinefu.com website. Quoting from their site:

Command-Line-Fu is the place to record those command-line gems that you return to again and again.

The script code is very “clean”. I can almost say that it’s written in a very python-ish way.
Sample output:%./cfu.pl
CMD: for (( i = 0; i < 100; i++ )); do echo "$i"; done
URL=http://www.commandlinefu.com/commands/view/735/perform-a-c-style-loop-in-bash. Title=Perform a C-style loop in Bash.
Description: Print 0 through 99, each on a separate line.
%./cfu.pl
CMD: rsync -av -e ssh user@host:/path/to/file.txt .
URL=http://www.commandlinefu.com/commands/view/20/synchronise-a-file-from-a-remote-server Title=Synchronise a file from a remote server
Description: You will be prompted for a password unless you have your public keys set-up.

You can get it from here: commandlinefu.com random entry parser perl script

As far as I’ve tested, it works out of the box on default perl installations of Debian, Gentoo and Mac OS X.

Filed by kargig at 01:28 under Gentoo,Internet,Linux,MacOSX
Tags: commandlinefu, debian, Gentoo, MacOSX, oneliner, parse, perl, script
3 Comments | 11,683 views

I am writing this post to provide some statistics on athcool + sata_sil usage. The results are horrible.

Athcool is a small utility, enabling/disabling Powersaving mode for AMD Athlon/Duron processors.
The homepage of the utility has a big fat warning as well:

WARNING: Depending on your motherboard and/or hardware components, enabling powersaving mode may cause:

* noisy or distorted sound playback
* a slowdown in harddisk performance
* system locks or instability

The Gentoo ebuild also has these warnings:

ewarn “WARNING: Depending on your motherboard and/or hardware components,”
ewarn “enabling powersaving mode may cause:”
ewarn ” * noisy or distorted sound playback”
ewarn ” * a slowdown in harddisk performance”
ewarn ” * system locks or unpredictable behavior”
ewarn ” * file system corruption”
ewarn “If you met those problems, you should not use athcool. Please use”
ewarn “athcool AT YOUR OWN RISK!”

Ignoring all these warning I was using athcool for years on my old desktop box filled with 2 IDE disks. Never had any real problem at all, except for a some performance loss. The problem appeared when I first used a sata disk on motherboard’s, Gigabyte GA-7VAXP-A Ulta, sata controller which uses the sata_sil module.
(more…)

Filed by kargig at 10:47 under Gentoo,Linux
Tags: athcool, bug, bug-report, bugzilla, dd, ext3, Gentoo, IDE, Linux, performance, powesaving, sata, sata_sil, vmstat
No Comments | 8,946 views

The Problem
To sum it up, the case is this: many many many web applications were programmed so that they used latin1 collation for their fields inside mysql databases. But most users now use utf8 from within their browsers. What happens is that utf8 characters are getting stored inside latin1 fields, which in return produces chaos! A huge web application that used that kind of madness was WordPress. Luckily (or not) WordPress now uses utf8 everywhere. I’ve known many many many people that got so frustrated when they tried to move from their old WordPress installation to a newer one because all their greek posts couldn’t be exported “easily”, I won’t say “properly” because there are always solutions to problems like this, but all the solutions were not straightforward at all, that they finally dumped the idea of moving the posts and started a new blog.

This is a HUGE problem for many greek (and not only) users and I hope I now have an elegant(?) solution to it.
(more…)

Filed by kargig at 21:14 under Greek,Internet,Linux
Tags: bash, convert, Greek, latin1, mysql, sed, utf8, wordpress
22 Comments | 38,571 views

A couple of days ago I’ve met a guy who has a high traffic blog about tech stuff. The guy was telling me that he has hosting problems and that his blog is getting slower and slower by the day. I’ve offered to help him by providing hosting for him in one of the servers that I administer. After making the transition from his old hosting to my server, which was not an easy thing to do due to latin1 to utf8 conversions that had to be made – it deserves a post of it’s own, I started to notice increased load on my server. Sure his blog had heavy traffic…but could it be that bad ?
(more…)

Filed by kargig at 13:49 under Linux
Tags: caching, db-cache, Linux, mysql, wordpress, wp-cache
10 Comments | 19,592 views

Following the request of comzeradd

answer the following questions with less than 50 words each (mind, only desktop/gui applications):
1. which desktop manager do you use more often ?
2. which desktop application you would not like to see implemented again on linux? and why?
3. which desktop application you definitely would like to see implemented on linux? describe it briefly or point out to a similar application.
4. write the name of the last project (not the very best, the last!) that made you wish to thank their developers so you can thank them now! 🙂

5.(optional) Link the blogs of 1-3 people you’d like to take part to this meme. (no more than three). you can skip this question if you like.

and here are my answers:

1. fluxbox
2. Audio players
3. I don’t have a single desktop application that I use on any other OS and I think it needs implementing on Linux, sure there are applications like CAD and serious audio/video editing for professionals missing, but I am sure that from the psychological point of view, if MS Office worked on linux a lot of people would feel much more comfortable switching to it. Just like what happens with MacOSX.
4. keepassX: excellent cross-platform tool to manage one’s passwords
5. stsimb, agorf, adamo

Filed by kargig at 22:29 under Linux
2 Comments | 5,467 views

Debian is one of the few distros that you can’t search the bash history backward or forward for past commands by default.
To change that behaviour you need to uncomment two lines inside /etc/inputrc.

Change:

# alternate mappings for "page up" and "page down" to search the history
# "\e[5~": history-search-backward
# "\e[6~": history-search-forward

To:

# alternate mappings for "page up" and "page down" to search the history
"\e[5~": history-search-backward
"\e[6~": history-search-forward


Example usage:
To search through your old commands that started with “ssh” (e.g. ssh -p 551 koko@lala.gr, ssh foo@bar.gr, ssh test@koko.gr -L1111:1.2.3.4:9876), just type ssh and hit PgUp, you will see the previous ssh commands appearing on the command line.
$ ssh[PgUp] transforms to $ ssh -p 551 koko@lala.gr hit PgUp again and it transforms to
$ ssh foo@bar.gr PgUp and it becomes $ ssh test@koko.gr -L1111:1.2.3.4:9876

Filed by kargig at 12:06 under Linux
6 Comments | 8,922 views

Dear Internet,

I need your help!
I have a debian stable (4.0) server with apache2 (Version: 2.2.3-4+etch6) running which is hosting more than 10 different sites. The problem is that in the apache2 error log I can see a lot of segfaults. All sites though continue to work properly and nobody has ever complained about them.

Some logs:

[Tue Feb 03 18:30:36 2009] [notice] child pid 1353 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:37 2009] [notice] child pid 29343 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:37 2009] [notice] child pid 1350 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:38 2009] [notice] child pid 1349 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:38 2009] [notice] child pid 1352 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:39 2009] [notice] child pid 1354 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:41 2009] [notice] child pid 1380 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:42 2009] [notice] child pid 1378 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:42 2009] [notice] child pid 1714 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:44 2009] [notice] child pid 1715 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:44 2009] [notice] child pid 1718 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:45 2009] [notice] child pid 1720 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:45 2009] [notice] child pid 1721 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:46 2009] [notice] child pid 1723 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:47 2009] [notice] child pid 1724 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:47 2009] [notice] child pid 1725 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:49 2009] [notice] child pid 1726 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:49 2009] [notice] child pid 1728 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:50 2009] [notice] child pid 1729 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:50 2009] [notice] child pid 1730 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:51 2009] [notice] child pid 1358 exit signal Segmentation fault (11)
[Tue Feb 03 18:30:51 2009] [notice] child pid 1733 exit signal Segmentation fault (11)

In order to find out what causes the segfaults I have enabled the following options:
inside /etc/apache2/apache2.conf
CoreDumpDirectory /tmp-apache/
$ ls -Fla / | grep tmp-apache
drwxrwxrwx 2 www-data www-data 4096 2009-01-31 11:01 tmp-apache/

I have changed the ulimit settings inside /etc/security/limits.conf
* soft core unlimited
* hard core unlimited

I have even added a ulimit -c unlimited setting inside /etc/init.d/apache2.
But still I get no core dumps inside /tmp-apache2/ from the segfaulting children.
If I manually kill -11 apache.pid then I can see a core file inside /tmp-apache/

I have only seen one or two core dumps generated by apache and using gdb I could see that they both “blamed” a function of /usr/lib/apache2/modules/libphp5.so. In my quest to find which site/code causes the segfaults I have recompiled apache2 to enable mod_whatkilledus. But no core dump was created in /tmp-apache/ for more than a week even if the segfaults keep happening.

I have reduced my modules, removed mod_python, mod_perl, etc and still these segfaults keep occuring but no core dumps. I suspect that the only time I got a core was when a parent and not a child process segfaulted. I don’t think that my apache2 children dump core when they segfault.

Is there anything I could have done and I haven’t done it ? Is there a way I can force apache2 children to dump core or any other way to determine what causes these segfaults ? All these without of course closing down the sites one by one to see when the segfaults stop…

Thanks in advance to anyone that replies!

P.S. blog’s database is making some tricks…I hope it’s ok now and the post is fully published

Filed by kargig at 22:41 under Linux
14 Comments | 17,325 views

As some people already know I’ve joined the army since 2 months ago, this makes it somewhat difficult for me to keep up with the latest updates for every machine I use.
Today I tried to upgrade a machine running stable (x86) Gentoo Linux after more than 15 days since the last upgrade and I got confronted with an epic Gentoo failure. The problem is clearly described on Odi’s blog. While trying to update e2fsprogs you have to uninstall the old version of them (so far so good), remove sys-libs/ss (that’s also acceptable) and remove sys-libs/com_err which is a dependency for MANY MANY progs, wget among them. So when you remove all these packages and try to install e2fsprogs-libs, wget can’t work anymore due to the missing libcom_err.so.2 file, so you can’t download the updates! You can’t open a new ssh connection to the machine either, so you can’t sftp the libcom_err.so.2 file from another machine! I had success by placing libcom_err.so.2 on a nfs share in another machine, mounting that share from the first machine and trying to re-emerge e2fsprogs-libs since wget could then work.

You can read more about the bug on Gentoo’s bugzilla, here and here.

a) Since portage is NOT ready to handle these kind of situations (according to bugzilla) why did the maintainers mark e2fsprogs-libs as stable ? Why didn’t they do ANY testing at all on the stable branch ?
b) Why wasn’t there a warning/alert/whatever on Gentoo’s website ?
c) It’s been more than 10 days since the problem first appeared and there hasn’t been any official solution about it, either by portage upgrade or by package masking.
d) Should I have googled or searched the forums before upgrading ? Possibly yes…but Gentoo didn’t have such upgrade problems before. I could accept it if problems on Gentoo were created by an upstream ABI breakage like dev-libs/expat had not so long ago, but this looks to me as a totally Gentoo related problem and not an upstream one.

I award Gentoo and e2fsprogs-libs maintainers a sad trombone. Sorry people but this is an epic failure. You deserve it.

Filed by kargig at 17:23 under Gentoo,Linux
16 Comments | 8,184 views

Following my previous post on minimizing the resources that urxvt needs on Gentoo, I tried applying some more patches to it that I found in Gentoo’s bugzilla.
Since that happened a few days ago there was no ebuild for version 9.05 yet. So I created one and applied the patch for the 256 color support.

Here’s my rxvt-unicode ebuild for version 9.05 with 256 color support: rxvt-unicode-9.05.ebuild.
(more…)

Filed by kargig at 02:14 under Gentoo,Linux
9 Comments | 43,603 views

451 CAOS Theory has a mini review of what’s going on with open source among the countries that compete in Euro 2008.
It’s quite interesting.
Here’s the link about Greece. It has quite a point…Things don’t look very promising…

Filed by kargig at 18:04 under Internet,Linux
No Comments | 4,612 views

Today, while studying I decided to manually run a prelink on my system. For no good reason. Just boredom I guess. The results were pretty interesting though.

Among the output there was a line that made a very big impression to me.
prelink: /usr/bin/urxvt: Cannot prelink against non-PIC shared library //usr//lib/opengl/nvidia/lib/libGL.so.1
Why oh why is libGL.so.1 inside the shared libraries of a terminal ???
(more…)

Filed by kargig at 01:09 under Gentoo,Linux
6 Comments | 10,393 views

When you are doing multiple ssh connections to one host there’s a way to speed them up by multiplexing them. When you open the first network connection a special socket is created and then all other connections to the destination machine pass through the first network connection and don’t open any new ones. All that is done via ControlMaster and ControlPath settings for ssh_config.

Example usage:
Inside /etc/ssh/ssh_config
ControlMaster auto
ControlPath /tmp/%r@%h:%p


Firsh ssh connection:
% ssh foobar@foo.bar.gr
Password:
Linux foo.bar.gr 2.6.20.1-1-686 #1 SMP Sun Mar 4 12:44:55 UTC 2007 i686 GNU/Linux
foobar@foo:~$


Second ssh connection:
% ssh -p 22 foobar@foo.bar.gr
Linux foo.bar.gr 2.6.20.1-1-686 #1 SMP Sun Mar 4 12:44:55 UTC 2007 i686 GNU/Linux
foobar@foo:~$

No password is asked and the connection opens up immediately.

kudos to apoikos for telling me about this neat feature in fosscomm 🙂

Filed by kargig at 11:50 under Encryption,Internet,Linux,Networking,Privacy
6 Comments | 5,798 views

Ο Δημήτρης έχει μια αρκετά καλή ανάλυση ενός attack σε ένα honeypot που έχει στήσει για πειραματισμούς. Αξίζει να του ρίξετε μια ματιά…

Επιτέλους μας την έπεσαν

Filed by kargig at 18:16 under General,Greek,Internet,Linux,Networking
No Comments | 5,740 views