Guy Rutenberg » Linux

Upgrading All QT Modules in Gentoo

Guy — Sat, 21 Nov 2009 20:01:06 +0000

Upgrading minor versions QT seems to be a hassle, as each version blocks the previous and because of inter-dependencies, Gentoo can’t understand by itself how to solve them. The solution is to tell it to specifically upgrade all installed modules.

sudo emerge -avu1 $(qlist -IvC /qt- | grep 4. | sed s/-4.*//)

This will allow Gentoo to solve the dependencies by uninstalling the old versions, unlike if you only try to upgrade a single package like x11-libs/qt-core

NVidia driver fails to initialize after X restart

Guy — Sat, 14 Nov 2009 15:19:14 +0000

This is mainly a note to myself. Sometimes when the X server is restart it complains that nvidia driver couldn’t be initialized and that no screens were found. This may be a result of a version mismatch between X11’s and the kernel’s nvidia module. The solution is to

modprobe -r nvidia

before restarting the X server.

Blocking IP Range using UFW

Guy — Sat, 07 Nov 2009 19:19:15 +0000

Uncomplicated Firewall (ufw) is one of the greatest frontends to IPTables I’ve encountered. It is very simple to use and I just wish it was also available for Gentoo. Up until recently everything went smoothly for me and ufw, but we hit some rough waters when I’ve tried to block an IP range.

To block an ip or I’p range in ufw you should do

sudo ufw deny from 188.162.67.197/21

But here is the catch. Only the recent versions of ufw (which the version that comes with Ubuntu 8.04 isn’t one of them) support inserting new rules. When you add a rule it gets appended. So if you had a rule before that allows everyone to connect to your server on port 80, it also allows the IP range you’re trying to block, to connect to your machine.

As it’s impossible to foresee all the rules you might use, one has to resort to deleting all the rules he has to override, then re-add them so they will be after the rule that blocks the IP range. However I disliked the idea and looked for a simpler solution.

The easiest method I’ve found was to manully edit ufw’s configurations:

sudo vim /var/lib/ufw/user.rules

And then move the rule I’ve added, which looks like this:

### tuple ### deny any any 0.0.0.0/0 any 188.162.67.197/21
-A ufw-user-input -s 188.162.67.197/21 -j DROP

above any other rules in the configuration file.

Afterward, you’ll have to restart ufw so it will reload its configurations.

sudo ufw disable
sudo ufw enable

Using Amarok Generated Playlists (m3u) on Sansa Clip

Guy — Sat, 11 Jul 2009 18:23:39 +0000

Few days ago, for the first time, I’ve created a playlist using Amarok for files on my Sansa Clip player. To my surprise (and disappointment) when I’ve unplugged my Sansa Clip and powered it, the playlist showed up empty, unlike playlists which originated in Windows. As I keep my music collection organized in Amarok, the situation seemed to be very uncomfortable.

I’ve decided to compare one of the working playlist files and the “empty” Amarok generated playlist. Two things were noticeable:

Amarok uses forward slashes, like in a Linux environment, and the working playlist used backward slashes.
The working playlist used relative paths without any prefix – directly beginning with the path. Amarok prefixed the relative paths with a dot-slash (./).

After noticing those things I’ve modified my Amarok generated playlist to look like the Windows generated one, and voila, it worked. I tried going through Amarok’s configuration dialogs to find some option controlling the format of generated m3u playlists, but couldn’t find any (I’m using Amarok 1.4.10). So with my newly found wits I’ve looked for a way to make using the playlists easier. I’ve came up with the following one-liner:

find -name "*.m3u" | xargs -I{} sed "s/^\.\///;s/\//\\\\/g" -i'' {}

The command should be run in the MUSIC directory of the Sansa Clip’s filesystem. It recursivey looks for m3u playlists and for each one strips any leading dot-slash and replaces forward slashes with backward ones. It can be used to easily convert all your playlists to the format understandable by Sansa Clip.

Upgrading All KDE Related Packages in Gentoo

Guy — Mon, 08 Jun 2009 06:24:01 +0000

Yesterday, Gentoo marked KDE 3.5.10 as stable on amd64. I looked for a way to upgrade all of the KDE related packages, without manually specifying each one of them. Normally one could do

emerge -avu world

but I encountered some nasty conflicts that I didn’t have time, nor will, to resolve at that time. So I’ve looked for a different solution. To my rescue came qlist for the great app-portage/portage-utils package. This package provides a set of very fast utilities to query portage. I’ve used qlist to list all of my installed packages, grep‘ed the list and piped the result as arguments to emerge using xargs.

 qlist -I --nocolor | grep kde | xargs emerge -pvu1

Take a look at the package list that will be merged. If everything looks fine, then do the actual merging.

 qlist -I --nocolor | grep kde | xargs sudo emerge -vu1

The --nocolor is important, or else emerge will complain about the benign looking atoms such as dev-util/kdevelop because there are invisible terminal formating characters around them.

Installing Lighttpd-1.4.22 on Ubuntu 8.04

Guy — Sun, 31 May 2009 19:43:19 +0000

I had some problems with the lighttpd-1.4.19 that comes with Ubuntu 8.04, mainly it’s problems of handling the HTTP header Expect: 100-continue (which older versions of Lighttpd return error 417). The problem was fixed in Lighttpd-1.4.21, but 1.4.22 is the newest version so I’ve decided to install it.

As I mentioned before, Ubuntu doesn’t have lighttpd-1.4.22 for 8.04, and it’s also not available in the updates or backports repositories. Fortunately, I’ve found that the package is available from Debuian Sid (unstable). Here are some instructions on how to install it.

Start By downloading the following packages.

wget http://ftp.de.debian.org/debian/pool/main/l/lighttpd/lighttpd_1.4.22-1_amd64.deb
wget http://ftp.de.debian.org/debian/pool/main/p/pcre3/libpcre3_7.8-2_amd64.deb

You can statisfy using the offical repositories all the dependencies of lighttpd-1.4.22 except the libpcre3, which is also available from Debian Sid. So start by installing it.

sudo dpkg -i libpcre3_7.8-2_amd64.deb
sudo aptitude markauto libpcre3

You statisfy the rest of the dependencies by using apt-get and the official repositories. In case you encounter the following problem when starting lighttpd:

/usr/sbin/lighttpd: Symbol `FamErrlist' has different size in shared object, con
sider re-linking

it can be solved easiliy by installing libfam3.

sudo apt-get install libfam3

(don’t worry if it complains about needing to remove libgamin0). You should be done now, and you can start enjoying your shining lighttpd-1.4.22.

Iptables Cheatsheet

Guy — Thu, 26 Feb 2009 06:19:47 +0000

From time to time I find myself having to go through man pages and googling for some simple iptable rules. This post is meant as a cheatsheet for me, so I can concentrate here various rules and remarks.

I hope others will benefit from this cheatsheet as well. Intend to expand it over time as I gather more rules and tips, so bookmarking the post might be a good idea. Last but not least, if you have some useful iptables rules I’ve missed please send them using the comments.

Blocking specific IPs

iptables -I INPUT -s "207.58.140.12" -j DROP

Blocking a range of IPs (IP block)

iptables -I INPUT -s "207.58.140.0/24" -j DROP

The number after the slash (/) determines the number of bits (starting with the most significant one) considered when matching an IP address. For example the above rule will block any packets from 207.58.140.* . Other useful number of bits are 16 (for matching the first two octets) and 8 (only the first octet).

Deleting rules

Just specify the rule after a -D flag. E.g.

iptables -D INPUT -s "207.58.140.12" -j DROP

Saving new rules

/etc/init.d/iptables save

Starting tracd without Root Privileges at Startup

Guy — Tue, 17 Feb 2009 17:28:20 +0000

I use Trac for the Open Yahtzee website. I’ve decided to use tracd for serving the requests (due to a configuration issue I didn’t want to mess with), which required starting it each time the server restarts. I’ve already written one solution for it, in the form of an init.d script for tracd. However, it bothered me that the tracd runs with root privileges which it doesn’t really requires.

After searching a bit I’ve found out that cron can run tasks on startup using the special @reboot keyword instead of the normal time fields. So edit your crontab and add the following line:

@reboot /usr/bin/tracd --daemonize --pidfile=~/run/tracd.pid --port=PORT --hostname=HOSTNAME -s TRAC_ENV

Just replace PORT, HOSTNAME and TRAC_ENV with the appropriate values for your environment, and make sure you got a run/ sub-directory in your home folder (or change the pidfile value).

To stop the server just do:

kill `cat ~/run/tracd.pid`

While there is no straight way to restart the server (like /etc/init.d/tracd restart), it’s a good compromise for dropping root privileges.

Amarok Sleep – Stop Playback After Specified Amount of Time

Guy — Wed, 04 Feb 2009 07:13:39 +0000

Amarok is my favourite music player. I like to listen to music when I go a sleep, but I don’t want the music to keep playing all night long. This is why I’ve added a sleep feature to radio.py. Unfortunately Amarok doesn’t have a built-in sleep functionality, but the Amarok developers left open door for us to implement it with ease by means of interfaces allowing to control amarok from the command line.

The first solution uses Amarok itself. The Amarok developers have provided means of controlling Amarok via the command-line. So we’ll combine this with the sleep command sleep command, and run the following in a console:



sleep 120m; amarok --stop

This will cause Amarok to stop after 120 minutes. The sleep command takes a number and a suffix which can be one of s, m, h and d (for seconds, minutes, hours and days). You can use it to easily set the duration before the playback halts.
Another solution, a more general one, would be to use DCOP. Amarok provides a very extensive DCOP interface that allows to control most of its features, including of course stopping the playback. So we could also use

sleep 1h; dcop amarok player stop

To stop Amarok in one hour.
A little note about the last solution. This post is written for Amarok 1.4 and not 2.0 as I didn't switch yet to KDE 4. DCOP was replaced in KDE 4 by D-Bus and the last solution would probably not work. However you could probably easily adjust it to the new D-Bus interface.



phpMyAdmin + Lighttpd in Gentoo
Guy — Tue, 20 Jan 2009 16:14:57 +0000
Usually installing software in Gentoo is a piece of cake. Just emerge what you want and (with the right USE flags) and everything will be ready for you. However, as today I’ve found out today, installing phpMyAdmin with Lighttpd isn’t trivial as it should be.
In this post I’ll try to walk you through the necessary steps to install phpMyAdmin with Lighttpd in Gentoo.


Installing Lighttpd and PHP
Before installing Lighttpd and PHP you’ll need to enable some USE flags. For Lighttpd you’ll need to at least enable the php and fastcgi USE flags. For PHP enable the cgi, crypt, ctype, pcre, session, unicode. The first one is required for working with Lighttpd, while the others are required for phpMyAdmin.
See the handbook for information about enabling USE flags.
Now install the packages

emerge -av lighttpd php

After installation is complete, start the Lighttpd process

/etc/init.d/lighttpd start

and you should have a working Lighttpd server with PHP support.
Installing phpMyAdmin
phpMyAdmin depends on a package called webapp-config. While usually we let Portage take care of dependencies, this time we’ll have to install webapp-config manually before we install phpMyAdmin, so we can change its configuration for suit Lighttpd.

emerge -av --oneshot webapp-config

After installation is done edit using your favourite editor the /etc/vhosts/webapp-config and change the line:

vhost_server="apache"

to

vhost_server="lighttpd"

Now we are ready to install phpMyAdmin.

emerge -av phpmyadmin

After installation is complete, you’ll need to create a phpMyAdmin configuration file

cp /var/www/localhost/htdocs/phpmyadmin/config.sample.inc.php /var/www/localhost/htdocs/phpmyadmin/config.inc.php

Now open the newly created configuration file and edit the line with the blowfish_secret (at the top of the file) as explained in it. An easy way to generate the password would be to use spass.
Now if you use the default Lighttpd configurations you’re done. You can access the phpMyAdmin via http://localhost/phpmyadmin. If however you’ve changed the document root, there is one more step for you. Enable the mod_alias module in /etc/lighttpd/lighttpd.conf and append to the file

alias.url += ("/phpmyadmin" => "/var/www/localhost/htdocs/phpmyadmin")

and don’t forget to restart the Lighttpd server after making the changes.
You should have by now everything installed and configured to work. If you have any further questions don’t hesitate to comment.