Unix Revelations

Workaround for licensing issues when connecting with rdesktop or KRDC

Bram Schoenmakers — Wed, 25 May 2011 15:54:41 +0200

This article shows a workaround whenever you cannot connect to a Windows Terminal Server anymore with either rdesktop or KRDC (which uses rdesktop). KRDC is an RDP client, part of the KDE distribution. Running rdesktop directly from the command line results in the following error:

$ rdesktop rdp.example.net
disconnect: No valid license available.

scponly: scp works but sftp doesn't

Bram Schoenmakers — Tue, 10 May 2011 23:20:09 +0200

Today I spent some time in getting scponly working. Actually my end goal was a chrooted sftp-only environment for users, so it took a while to get all binaries and libraries together. In an attempt to make life easier, I raised the scponly's debuglevel to 2, to see slightly more output than Connection closed when trying to log in.

Debian: logrotate fails when MySQL is not running

Bram Schoenmakers — Wed, 19 Jan 2011 01:24:36 +0100

I have a MySQL instance on my PC, but by default it's turned off. However, when I leave my PC running overnight, the next morning I find this friendly email from a person called Cron:

/etc/cron.daily/logrotate:
error: error running shared postrotate script for '/var/log/mysql.log /var/log/mysql/mysql.log /var/log/mysql/mysql-slow.log '
run-parts: /etc/cron.daily/logrotate exited with return code 1
Job run-parts --report /etc/cron.daily terminated (exit status: 1) (mailing output)

How to install VMWare tools in Debian Lenny

Bram Schoenmakers — Fri, 26 Nov 2010 13:20:33 +0100

Every VMWare guest should have the VMWare tools installed. This improves the performance of the VM, especially when the VMWare host is under heavy load. Here are the instructions to install these in a Debian Lenny guest system:

Rotate MySQL log files with newsyslog

Bram Schoenmakers — Wed, 21 Jul 2010 13:12:38 +0200

When you log slow queries or queries without indexes in MySQL, you should regularly rotate the file to save disk space. Quite some suggestions on the internet involve complex scripts which do this, other suggestions discuss FreeBSD's log rotator newsyslog. However, most of the descriptions about newsyslog appeared wrong to me, because no PID file was specified for the rule. This means that a SIGHUP is sent to the syslog daemon instead of the mysqld process, which is undesired.

tmux 1.3: equivalents for down-pane and up-pane

Bram Schoenmakers — Tue, 20 Jul 2010 10:15:59 +0200

tmux is a terminal multiplexer, just like screen(1). However, tmux is actively maintained and is in my opinion much better. Due to these developments, it could happen that something stops working or becomes broken from one version to another. The upgrade from version 1.2 to 1.3 caused that the commands down-pane and up-pane were no longer working.

R: Increase heap size for rJava

Bram Schoenmakers — Thu, 10 Jun 2010 01:15:33 +0200

Technically speaking, this is not strictly a Unix Revelation. Still, to me it's useful enough to note this down.

We all know Java runs in a virtual machine, and assigns itself in 80% of the cases too little memory to do some real work. Result? Well, this:

java.lang.OutOfMemoryError: Java heap space

Sun gave us the -Xmx flag to increase the heap size (and -Xms to increase the stack size).

This works nicely from the commandline, the next challenge was to do something similar from an R environment. Using RWeka, which in turn depends on rJava, I found myself hitting the limit every time (which defaults to 512 MB).

Tethering in Linux with HTC Desire

Bram Schoenmakers — Fri, 23 Apr 2010 22:06:40 +0200

Again, this is primarily a note-to-self. My normal internet connection is not always that stable, so I have to fallback to alternatives when things are suboptimal (massive packet loss up to 100%).

Before, I could use my Sony Ericsson C902 for tethering. With Bluetooth and a lot of PPP magic I barely understand, I was able to call my phone's modem and access the internet.

Git remote repository with a custom SSH port

Bram Schoenmakers — Fri, 12 Mar 2010 00:02:52 +0100

I keep forgetting this, so I'd better jot it down here once and for all. To add a Git remote repository, accessible through SSH with a different port than 22, execute:

git remote add office ssh://username@hostname:2222/home/bram/.repository

So this adds a remote repository behind port 2222 of the host, immediately followed by the remote path of the repository. The ssh:// part is crucial and forgetting this part has cost already some minutes of my life.

Allow other local users to run X11 applications

Bram Schoenmakers — Sun, 27 Dec 2009 00:27:57 +0100

For KDE development, I work with a separate user. However, when you invoke su - kde-devel and run an X11 application, you'll get nasty errors like:

kfoo: cannot connect to X server :0.0

X11 initialization failed.

There are several solutions for this.

GMail backup with offlineimap and Git

Bram Schoenmakers — Wed, 16 Dec 2009 01:43:10 +0100

A couple of days ago I came across this excellent tip to download your GMail mail to your computer with IMAP. Before you continue reading here, I assume you read that article first. In this article, the path /path/to/gmail/backup is the path of the local repository, which you configured for offlineimap.

In the comments of that article, I stated that there's a problem with duplicate files. GMail has no real folders, but you can label e-mails. This implies that the same e-mail may possibly end up in more than one folder. When you download all folders, it is likely you retrieve and store that e-mail multiple times.

x11vnc: Shift key does not work

Bram Schoenmakers — Wed, 16 Dec 2009 00:24:10 +0100

An annoying problem arised when using x11vnc as a VNC server on one of my machines. Whenever I connected to it the Shift key did not appear to work from the client. For some people this is no problem because they have no notion about using capitals, but I do care. I tried two clients, both showing the same behavior, so I knew this was a server-side issue. Running xev (package xorg-tools) on the server showed me the desired behavior: the Shift key got captured after all. And Caps-Lock also just works.

KDE 3.5.10: White noise when ripping audio CDs to MP3

Bram Schoenmakers — Wed, 02 Dec 2009 13:22:13 +0100

One of the Arch Linux systems I maintain is still running KDE 3 from the KDEmod repositories. We're talking about KDE 3.5.10 here. Unfortunately, there's a bug in the audio CD ripping process. When you drag a (virtual) MP3 file/folder from the audiocd:// KIO-slave, it produces only MP3 files with white noise. Unless your audio CD contains white noise only, there's no problem of course, in other cases you might like to fix this.

Git: checkout by date

Bram Schoenmakers — Mon, 27 Jul 2009 11:05:39 +0200

Sometimes it's handy to checkout a branch based on a point in time.

git checkout master@{2009-07-27 13:37}

will not work, because it uses the reflog (which expires after some time).

The trick (as found on Nabble) is to lookup the revision on a certain date and check out that revision. This can be done in a single command:

git checkout `git rev-list -n 1 --before="2009-07-27 13:37" master`

Show current Git branch and status in your prompt

Bram Schoenmakers — Wed, 17 Jun 2009 21:52:28 +0200

Those who use git frequently will often execute commands like git status and git branch to check which branch you're on and if there are pending changes.

Fortunately, git offers a Bash script which automatically shows the current state of your repository in your prompt.

Debugging a Google Webkit project with JDB

Bram Schoenmakers — Wed, 17 Jun 2009 20:51:52 +0200

I followed the tutorial of Google Web Toolkit and I must say it looks quite nice. Now I want to start a project with this toolkit, but I need a way to debug my code.

A script to clean up Okular metadata

Bram Schoenmakers — Tue, 09 Jun 2009 19:59:45 +0200

Okular, the PDF viewer for KDE, stores some metadata for the documents you have opened in the past. For example, it stores the position within the document whenever you close it, or the annotations you've made while auditing a document.

However, this metadata is not cleaned up automatically. This results in many files in the Okular data folder about files you have removed a long time ago. The following little script cleans all metadata of non-existent files for you. It is recommended to put this in a weekly cron job, so you never have to think of it again.

phpdocumentor: Bad environment variable $PHP

Bram Schoenmakers — Wed, 27 May 2009 10:35:29 +0200

I tried to create a local API reference of the Zend Framework on our local network, with the PhpDocumentor tool. However, along the process it stops with the following error:

FAILED: Bad environment variable: $PHP (set to "/usr/bin/php")

PuTTY: Wrong function key codes sent to server

Bram Schoenmakers — Wed, 13 May 2009 12:23:12 +0200

For a little while I use xdebug and vim in order to debug PHP code (see the vim-debugger module). With the F2, F3 and F4 keys you can step through the code. However, all of a sudden the functions keys did not do what I expected. With every function key I pressed vim complained with:

E21: Cannot make changes, 'modifiable' is off

pure-ftpd: Invalid SQL configuration file

Bram Schoenmakers — Fri, 08 May 2009 15:56:07 +0200

When starting the Pure-FTPd daemon I came across the following error:

pure-ftpd: (?@?) [ERROR] Configuration error: Invalid SQL configuration file: /etc/pureftpd-mysql.conf

5 hidden KDE commands for the command line

Bram Schoenmakers — Fri, 17 Apr 2009 19:25:19 +0200

By default, KDE comes with a number of programs which may come in handy from time to time in the shell. It is possible to embed some KDE technology inside a script. This articles shows 5 commands which you will not encounter in your application menu: kdialog, kioclient, ktrash, kquitapp and kdebugdialog.

Control KDE applications from the commandline with D-Bus

Bram Schoenmakers — Fri, 17 Apr 2009 19:07:47 +0200

This is more or less a follow-up on my previous article, but this time we focus on how to communicate with KDE applications from the commandline. This is done with D-Bus and for that we'll use the qdbus command. For example, it's possible to request the current track information in Amraok, or you could set your Kopete status on Away.

mailwrapper: no mapping in /etc/mail/mailer.conf

Bram Schoenmakers — Fri, 10 Apr 2009 16:27:41 +0200

In the daily status mails I found the following lines:

Removing stale entries from sendmail host status cache:
mailwrapper: no mapping in /etc/mail/mailer.conf

Installing a custom kernel in Arch Linux

Bram Schoenmakers — Mon, 23 Mar 2009 10:04:16 +0100

In the past I have experienced quite some annoyances with running Arch Linux on VirtualBox.

Before VirtualBox 2.0 there was something horribly wrong with the disk drivers. If you did slightly more disk I/O than average there was a fair chance you would end up with a kernel panic. Besides, VirtualBox does some spurious logging, trying to tell you that the disk does not work properly. It was very easy to lose gigabytes of host disk space because of the ever-growing logfiles.

ATI Radeon: Getting OpenGL right on Arch Linux

Bram Schoenmakers — Thu, 05 Mar 2009 22:10:53 +0100

A year ago I wrote a rather successful article on getting OpenGL right on a Gentoo Linux system. It was not straightforward to do and it I must confess the graphics setup didn't work anymore after a while. But still it appears to be of help to some people.

Now I switched to Arch Linux I had to get this right again. And it turned out to be so much simpler!

Install/upgrade a FreeBSD port despite vulnerability warnings

Bram Schoenmakers — Mon, 23 Feb 2009 13:43:22 +0100

I tried to upgrade ZendFramework from 1.5.2 to ZendFramework 1.7.0. At that time, version 1.7.5 was already released, but I wanted 1.7.0 no matter what. However, when trying to do so with the clumsy portdowngrade and then portupgrade, the following error appeared:

Archive exception with encfs

Bram Schoenmakers — Mon, 23 Feb 2009 10:04:57 +0100

Trying to mount my EncFS filesystem resulted in the following error:

09:45:36 (FileUtils.cpp:375) Archive exception: stream error
09:45:36 (FileUtils.cpp:326) Found config file /home/bram/Backup/.encfs6.xml, but failed to load

Followed by the the ability to create a new encfs system. This happened because I created the .encfs6.xml file with a newer Boost version on another system. Upgrading Boost to the same version as on my other machine made encfs work again.

MySQL: Lost connection to MySQL server at 'reading initial communication packet'

Bram Schoenmakers — Wed, 04 Feb 2009 16:41:15 +0100

At some point, it was impossible for remote clients to connect to the MySQL server. The client (some application on a Windows platform) gave a vague description like Connection unexpectedly terminated. When remotely logging in with the MySQL client the following error appeared:

ERROR 2013 (HY000): Lost connection to MySQL server at 'reading initial communication packet', system error: 0

QMail: Limit connections from an IP address or range

Bram Schoenmakers — Mon, 15 Dec 2008 14:16:36 +0100

In order to limit the connections made from a certain IP address, one needs to patch tcpserver, the process which receives all incoming connections and passes them through to QMail. These steps describe how to patch tcpserver on a FreeBSD system, where the QMail SMTP and POP servers are executed with the supervise (svc) daemon.

Let Nagios check on a non-default SSH port

Bram Schoenmakers — Fri, 12 Dec 2008 15:41:08 +0100

In Nagios, I wanted to let one particular host (out of many) to be checked with a different SSH port. In the checkcommands.cfg file, you will find commands which need to be checked remotely written as follows:

define command{
        command_name check_somecommand_remote
        command_line $USER1$/check_by_ssh -i /usr/local/etc/nagios/keys/id_dsa -l nagioscheck -H $HOSTADDRESS$ -C "/path/to/command -w $ARG1$ -c $ARG2$"
        }

This does not allow you to let a host use another SSH port. There are many other hosts which just work fine like this (since all hosts have the default port 22 set), it's just one particular host using SSH port 24. I could also redefine all remote commands by adding a -p 24 but this is inflexible. I would need a new set of commands for each different port number.

Nagios plugin check_mailq shows "mailq returns code 111"

Bram Schoenmakers — Mon, 17 Nov 2008 16:32:03 +0100

On a recently installed machine, the Nagios check for mailq did not work. Instead it returned the following error:

Error code 111 returned from /usr/bin/mailq

This is on a QMail based machine running on FreeBSD. I compared the setup with an older FreeBSD machine, where the check works properly. This box was also running QMail but with an older set of Nagios plugins. The configuration was equal, except the check_mailq script itself, because it has evolved a little in the meantime.

How to make backups with Git using gibak

Bram Schoenmakers — Sun, 09 Nov 2008 01:06:32 +0100

Due to circumstances I had to look for a new way to backup my home directory. I was using rdiff-backup(1) before, but I wasn't completely satisfied with it. The overhead of incremental data was quite large, especially if you moved files around. But overall it does its job quite well.

However, since a year or so I'm quite charmed of Git, the stupid file content tracker. It's a great tool for software development, but due to its advantages over other VCSs it's also suitable for backing up structures like a user's home directory.

Converting a APE+CUE file to separate FLAC files

Bram Schoenmakers — Thu, 09 Oct 2008 12:50:03 +0200

APE files are, besides lossless audio files, also quite annoying; they're barely supported on non-Windows platforms. There's a way to convert them to FLAC. It took me some time because I had to combine several pieces from the internet in order to convert a single *.ape file to multiple per-track *.flac files.

There are tools for Linux to encode and decode *.ape files. On the internet it is referred as mac-port, but everyone links to a SourceForge page which is dead by now. But I found a tarball from the Slackware servers which does its job. The tarball is also included with this article.

Hardware of a VirtualBox

Bram Schoenmakers — Sun, 05 Oct 2008 21:55:27 +0200

Just for reference I paste here the output of the lshw tool, ran on a VirtualBox (1.6.4):

Highlight command's output with colors using sed

Bram Schoenmakers — Thu, 02 Oct 2008 13:09:02 +0200

For some reason I wanted to highlight some lines during a rsync(1) session, those lines indicating that a file is going to be deleted. Doing the following command right on the command line didn't work:

ClamAV: Missing *.cvd files and undefined references

Bram Schoenmakers — Wed, 10 Sep 2008 11:23:09 +0200

At a certain point, ClamAV 0.93 was not running anymore and complained with the following message as soon as you tried to start it:

Missing /var/db/clamav/clamav/*.cvd files. You must run a freshclam first.

It appears that the quickest solution is to update ClamAV to 0.93.3 or higher. However, compiling ClamAV 0.93.3 on a FreeBSD 6.1 machine (or earlier) causes the following error:

undefined reference to `gethostbyname_r'

lnc0 causes problems in FreeBSD running inside ESX

Bram Schoenmakers — Tue, 19 Aug 2008 16:17:40 +0200

Running a FreeBSD 6.x guest on an ESX server may cause the following lines on the console:

lnc0: Missed packet -- no receive buffer

This renders the system pretty unusable. The shape of the lnc driver is not that good (hence it has been deprecated from FreeBSD 7 and replaced by the le driver). Fortunately, VMWare ESX offers another network interface which works better in combination with FreeBSD. To switch network interface, follow these steps:

Open the VMWare Infrastructure Client.
Shut down the FreeBSD guest.

Installing VMWare ESX 3i on a HP Proliant DL160 G5

Bram Schoenmakers — Tue, 19 Aug 2008 15:27:06 +0200

Installing VMWare ESX 3i (3.5.0) on a Hewlet Packard Proliant DL160 G5 could cause problems. It could hang at some stage where it says Enabling interrupts. This is because by default ACPI is enabled and causes problems.

Printing rule numbers with ipfstat

Bram Schoenmakers — Fri, 01 Aug 2008 11:00:19 +0200

The FreeBSD manual about ipmon(8) has flaw which is a bit annoying. This post is just a quick reminder for me in order to report it, so that it can be fixed.

The man page of ipmon(8) describes the fields which are printed in its output. One of these fields has the following texts:

4. The group and rule number of the rule, e.g., @0:17. These can be viewed with ipfstat -n.

Installing chkuser 2.0 QMail patch with FreeBSD ports

Bram Schoenmakers — Thu, 24 Jul 2008 17:05:25 +0200

chkuser is a patch for QMail 1.03 which checks if the recipient address is a valid user on the system. If not, it will block the mail right away. This is nice, because usually this is checked after scanning a mail for virusses and spam. Now this is checked beforehand, which saves you a lot of CPU cycles.

MySQL: Can't start server : Bind on unix socket: Permission denied

Bram Schoenmakers — Wed, 23 Jul 2008 12:34:44 +0200

I copied the filesystem from one host to another, hoping that things would 'just work'. But that was a bit too optimistic, there was no way I could MySQL going again. This is what was reported in the error logs:

Obtaining a window title given only a process ID (PID)

Bram Schoenmakers — Sat, 19 Jul 2008 01:29:14 +0200

It's not that obvious to obtain the window title when you only have the process ID (PID) of the process showing that window. xprop(1) and xwininfo(1) didn't work for me, because these were interactive commands. Finally I found the wmctrl(1) tool, which should work fine with most major window managers (KWin for example).

The following command obtains the window title of the process with PID 1234 and having a window managed by your window manager:

FreeBSD SMP kernels cause problems on VMWare

Bram Schoenmakers — Fri, 18 Jul 2008 17:08:17 +0200

This entry is quite simple: don't use SMP FreeBSD kernels on a VMWare virtual machine. This gives many problems, illustrated with this snippet from dmesg:

Git: broken hooks prevent doing a commit

Bram Schoenmakers — Tue, 15 Jul 2008 12:33:37 +0200

When trying to commit a change set, git gave the following error:

fatal: exec /path/.git/hooks/pre-commit failed.

It seems that the hooks went broken somehow. Since I don't have any custom hooks, I moved the .git/hooks folder away and created an empty one. Committing to the repository works again.

How to fix those small fonts in Google Earth

Bram Schoenmakers — Sat, 28 Jun 2008 21:50:04 +0200

On some setups, like mine, the GUI font for Google Earth is incredibly small. There are some hints on the internet on how to fix that, but they are slightly outdated. This is more or less an update, using Google Earth 4.2.205.5730 . To set the fontsize to 12 execute:

echo 12 > ~/.googleearth/Registry/google/googleearthplus/User/render/guifontsize

Debugging a Qt application which grabs keyboard

Bram Schoenmakers — Sat, 28 Jun 2008 17:23:32 +0200

When running a Qt application with a debugger (gdb), the option --nograb is implicitly passed to the application. This prevents the application from stealing your keyboard, so you're still in control of the console where GDB runs if something goes wrong.

mysqldump gives error 1064

Bram Schoenmakers — Tue, 24 Jun 2008 12:56:46 +0200

I tried to backup a database with the mysqldump command, but got the following error:

mysqldump: Couldn't execute 'use example.com': You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '.com' at line 1 (1064)

It seems the database name is not properly escaped and the . is misinterpreted.

Installing SSL Explorer on FreeBSD 6.x

Bram Schoenmakers — Fri, 13 Jun 2008 16:58:09 +0200

SSL Explorer is a Java based SSL VPN solution. It supports FreeBSD, but things seem to be a bit outdated by now and installing it is not really straight-forward. After a little of fiddling I came to these steps to install SSL Explorer on FreeBSD 6.3:

Apache cannot find server name

Bram Schoenmakers — Thu, 05 Jun 2008 22:11:14 +0200

When starting Apache for the first time, I came across this error message in httpd-error.log:

unable to find IPv4 address of "servername"

The solution was obvious, but couldn't think of it immediately. So by writing it down here I'm sure I'll never forget.

Add the hostname to /etc/hosts!

127.0.0.1 servername

sa-update: error: GPG validation failed!

Bram Schoenmakers — Thu, 22 May 2008 21:43:35 +0200

When updating the SpamAssassin rules I encountered the following error:

error: GPG validation failed!
The update downloaded successfully, but the GPG signature verification failed.
channel: GPG validation failed, channel failed

The solution isn't too hard fortunately, but I couldn't find it from 'official' resources.

$ wget http://spamassassin.apache.org/updates/GPG.KEY
$ sa-update --import GPG.KEY

Blending GTK applications with your Qt/KDE desktop

Bram Schoenmakers — Sat, 26 Apr 2008 10:55:58 +0200

As a KDE user I got pretty tired of the ugly default looks of GTK applications (and also WX applications in Linux, they have the same looks). They looked cool in 1997, but these times are over now. And all the time I was too lazy to find out how I could theme GTK, but I didn't realize it was really simple. These are the steps on a Gentoo machine:

First a new GTK theme is installed. This is a special one, because it uses Qt for all drawing operations.

emerge -av x11-themes/gtk-engines-qt

Removing missing files from a Git repository

Bram Schoenmakers — Sat, 26 Apr 2008 01:11:24 +0200

It is a bit cumbersome to call git rm for every missing file in a directory tree tracked by Git. Fortunately, this following command will solve this problem instantly:

git ls-files -d -z | xargs -0 git update-index --remove

Note: this command works from the current working directory, not the root directory of the Git repository.

FreeBSD equivalent for watch(1)

Bram Schoenmakers — Mon, 14 Apr 2008 16:18:17 +0200

The command in Linux can be pretty handy sometimes, but I was missing that command in FreeBSD. There is a watch command but it didn't seem to do what I expected it to do.

But about a week ago I found out there's an equivalent application in the ports tree: sysutils/cmdwatch. Good to find out, finally.

Using EncFS with GMailFS

Bram Schoenmakers — Sat, 05 Apr 2008 12:48:54 +0200

As promised, I would write here whenever I succeeded to make encfs work together with GMailFS. Because Google is nice, but I don't trust them enough to have my files over there in readable format.

I tried encfs back then in October 2007, but that didn't work out. That was encfs 1.3.x. In January this year, version 1.4.0 was released and currently the latest version is 1.4.1.1. The ebuild is to be found in Gentoo Bugzilla.

VirtualBox: Network interface does not work in FreeBSD 7.0

Bram Schoenmakers — Mon, 31 Mar 2008 15:55:30 +0200

The network interface used by FreeBSD when running inside VirtualBox is usually pcn0 and worked fine up to FreeBSD 6.2 (using NAT). However, the card did not seem to be working that great in FreeBSD 7.0. No IP address was being assigned and I failed to manage how to obtain one nevertheless.

Relation between CPU nice and I/O nice

Bram Schoenmakers — Sat, 29 Mar 2008 11:01:05 +0100

I feel a bit ashamed about it, but after all those years of using Linux, I discovered the ionice(1) command only yesterday. Where nice(1) affects the CPU scheduler, ionice affects the disk scheduler. This article explains the command pretty well, so I'd recommend you to read it first.

Why I prefer higher swappiness

Bram Schoenmakers — Wed, 26 Mar 2008 23:18:27 +0100

In the online article Tales from Responsivenessland: Why Linux Feels Slow And How To Fix That it is suggested to lower your swappiness in order to obtain more responsive applications in Linux. The main reason for this suggestion was "Screw data, prioritize code". So application's code won't get swapped away and is quickly accessible when the user needs it.

git-svn: path probably does not exist

Bram Schoenmakers — Tue, 25 Mar 2008 22:48:27 +0100

I wanted to check out a folder from the KDE Subversion repository as a git repository, so I used the git-svn tool to accomplish that. These were the steps I followed:

git svn init \
https://bram@svn.kde.org/home/kde/trunk/extragear/utils/rsibreak
git svn fetch

But that didn't work out, I got the following error:

FreeBSD boot stalls at "Timecounters tick every 1.000 ms"

Bram Schoenmakers — Thu, 20 Mar 2008 11:31:23 +0100

FreeBSD 6.2 sometimes stops booting the kernel, with the last message on screen:

Timecounters tick every 1.000 ms

This was a SMP kernel. As soon as I switched back to a GENERIC kernel, I haven't seen this behavior anymore.

Something to investigate better whenever I have more time, but it's a good temporary fix

Update 28 March 2008:

How to specify an output directory for split(1)

Bram Schoenmakers — Sat, 08 Mar 2008 18:09:30 +0100

I had to transfer a big file to some remote site, and have it split up there. So something like:

cat some_big_file | ssh bram@example.com split

However, the split(1) utility does not have a command line option to specify an output directory. It only puts files in the current working directory, which is undesired in this case. But /bin/sh to the rescue, it is possible:

cat some_big_file | ssh bram@example.com 'sh -c "cd /remote/dest/dir; split"'

Renewed SSL certificate does not show up with Apache

Bram Schoenmakers — Thu, 06 Mar 2008 10:58:19 +0100

I installed a renewed SSL certificate on a webserver (Apache 1.3), replacing the old certificate with the newer one. However, when one checks the SSL page in the internet browser, the data of the old certificate may be seen. This is a known issue with Apache. But restarting the webserver did not work out. But it turned out that I didn't start the server with SSL support. These are the commands which should be issued after replacing a certificate:

apachectl stop && apachectl startssl

And after this command the new certificate was shown in the browser.

Simscan does not scan incoming mail after upgrade

Bram Schoenmakers — Fri, 22 Feb 2008 13:40:31 +0100

After upgrading simscan, mails did not seem to be scanned anymore.

In order to debug what was going on, I entered the following command in order to see what happened to QMail:

env QMAILQUEUE="/var/qmail/bin/simscan" SIMSCAN_DEBUG="5" qmail-inject test@example.com < test

fcron 3.0.4 uses wrong times for next execution of jobs

Bram Schoenmakers — Mon, 11 Feb 2008 20:37:12 +0100

I noticed that my cron jobs were not being run since I upgraded from FCron 3.0.3 to 3.0.4. Running

kill -SIGUSR2 `pidof fcron` && less /var/log/syslog

confirmed this: some (daily) jobs were scheduled for next month. Some jobs even had their next execution time in the past. Something got hosed.

Fortunately, it's not hard to fix this. For every user run as root:

fcrontab -z username

to reschedule all your jobs. It's weird, this shouldn't have happened in the first place.

Make sure LaTeX plugin works in Kopete

Bram Schoenmakers — Thu, 31 Jan 2008 22:51:41 +0100

Yesterday I installed the LaTeX plugin for Kopete, but after a couple of restarts of Kopete I didn't manage it to work. The text remained unfiltered so I saw $$\sqrt(x)$$ all the time.

It seems I had an option enabled in the Kopete settings which disabled filtering of the text. After I disabled Settings->Configure->Appearance->Colors & Fonts->Do not show user specified rich text I could see the LaTeX output.

Watch out with du(1) and the block size it assumes

Bram Schoenmakers — Sat, 26 Jan 2008 17:54:34 +0100

Today I encountered this strange effect on a FreeBSD machine:

# du -s /some/dir
53982 /some/dir
# sudo du -s /some/dir
107964 /some/dir

When invoking du with sudo, it returns double the size of the actual size. It took me an hour or two to find out what was going on.

As always, I should read manpages more carefully:

Getting X.org to work on Gentoo guest in VirtualBox

Bram Schoenmakers — Thu, 24 Jan 2008 23:19:26 +0100

Unfortunately, X.org does not work out of the box when installing it inside VirtualBox on a Gentoo guest machine.

The VESA driver didn't really work when starting X, it spitted out the following line:

(EE) VESA(0): unknown type(0xffffffff)=0xff

Well, maybe the VirtualBox Guest Additions will help out. They installed without a glitch on the Gentoo guest, but when starting X I got a similar error as above, only VESA replaced with some VirtualBox stuff.

Doing Ctrl+Alt+F1 in VirtualBox

Bram Schoenmakers — Thu, 24 Jan 2008 17:09:47 +0100

A common problem for people running a Linux guest on a Linux host with VirtualBox: bashing Ctrl+Alt+F1 does not have the desired effect, it switches to your first virtual terminal on your host OS while nothing happens in the guest OS. There are two ways of entering Ctrl+Alt+F1 targeting the guest OS:

HostKey + F1 (where HostKey is often the right Ctrl key)
First press F1, then Ctrl and then Alt. Your host OS won't pick it up but the guest OS will.

Now I've noted this down I won't forget this anymore.

Increase efficiency of bandwidth and disk space with rdiff

Bram Schoenmakers — Thu, 24 Jan 2008 00:47:09 +0100

The rdiff command line tool is a bit lousy documented if you ask me, so maybe it's a good idea to write some more about it.

Usually, the functionality provided by rdiff is used by rdiff-backup and rsync. In these cases there's no need to know how rdiff works. But in some cases you want to use the rdiff tool directly.

Sharing Gentoo Portage over NFS

Bram Schoenmakers — Sat, 19 Jan 2008 14:22:58 +0100

When having more than one Gentoo installation at the same location, you should seriously consider sharing the Portage tree to avoid a lot of unnecessary downloads. This can be done by having the tree on only one machine and share it with NFS, the Network File System.

Server (Gentoo Linux)
First, we're going to configure the server, having the Portage tree installed in /usr/portage. I suggest following the first half of my previous article on setting up a NFS connection between Gentoo and FreeBSD.

Passwordless SSH login still asks for password

Bram Schoenmakers — Fri, 18 Jan 2008 10:25:11 +0100

For some script a passwordless SSH login was required. However, despite the public key had no passphrase set, a password was being asked nevertheless.

The SSH client is not really verbose on what was going on, but it turned out to be the private key's permissions. When the permissions are too open, SSH refuses to use that key and falls back to something else. So make sure that they key has mode 600 (read and write only for the owner of the key) and that the owner is OK.

How to run Google Earth on open source Radeon drivers

Bram Schoenmakers — Mon, 07 Jan 2008 16:32:11 +0100

It's been a real pain to enable graphics hardware acceleration on my 3.5 year old IBM Thinkpad T42, containing an ATI Radeon 9600 (Mobility). The binary drivers by ATI are just plain crap, causing insane instability to the system (kernel panics everywhere). I called it a day and continued working without acceleration. But applications like Google Earth are a real pain to use like this, so something inside me shouted to get this right.

Be notified before every regular fsck

Bram Schoenmakers — Sat, 05 Jan 2008 11:13:26 +0100

All Linux users have experienced this so far: you boot you computer or laptop just to do something quickly, and then the fsck kicks in and scans your partitions. A process which can take several minutes.

Send Portage output to e-mail

Bram Schoenmakers — Thu, 03 Jan 2008 13:39:35 +0100

According to one bug wrangler on Gentoo Bugzilla, you're a stupid person if you don't read the messages spitted out by ebuilds and run into failures because of that. Of course, no sane person watches the complete compilations of application on the lookout for warnings or other informative messages. But it would be nice if you get a nice summary of all messages in your mailbox after an emerge command.

Dropping the disk cache in Linux

Bram Schoenmakers — Sat, 29 Dec 2007 18:35:16 +0100

In Linux the (physical) memory is not only a place for processes to dump their data onto. It also acts as an extra layer between the processes in memory and relatively slow hard disks. Free space in RAM will be filled with data from the harddisk, so they are quickly accessible whenever a process wants data which was retrieved earlier from disk. This greatly improves the performance of your system.

Git: protocol error: bad line length character

Bram Schoenmakers — Thu, 13 Dec 2007 23:04:52 +0100

Doing a git clone/pull/push command might result in the following error message:

Initialized empty Git repository in /home/bram/tmp/Filesystem/.git/
Password:
fatal: protocol error: bad line length character
fetch-pack from 'ssh://bram@xxx.xxx.xxx.xxx/home/bram/Filesystem' failed.

Unknown symbols in Linux kernel modules

Bram Schoenmakers — Tue, 11 Dec 2007 13:47:20 +0100

For an assignment we have to write a module to read a file from the filesystem and make a virtual filesystem for it. Good, with this sentence we continue for the people who still care, since all kernel developers have clicked away this page. Screaming.

Speed up the creation of the locate database with mlocate

Bram Schoenmakers — Sun, 09 Dec 2007 00:41:05 +0100

Today I stumbled upon something interesting: the mlocate package. It's a replacement for the more traditional slocate package which offers the locate and updatedb commands for quick file lookup.

Mailing list creation with QMailAdmin fails

Bram Schoenmakers — Fri, 07 Dec 2007 14:19:39 +0100

Installing QMailAdmin from FreeBSD ports also installed the ezmlm-idx package. QMailAdmin worked quite good except when creating mailing lists. It showed an error like No mailing lists found (translated from Dutch) after submitting a request to create a mailing list.

VMWare Player refuses to start

Bram Schoenmakers — Sun, 02 Dec 2007 22:41:58 +0100

This application is not a breeze to get running on Gentoo. After emerging it, and executing the script /opt/vmware/player/bin/vmware-config.pl, it still complained with the following error when running vmplayer:

vmware is installed, but it has not been (correctly) configured
for this system. To (re-)configure it, invoke the following command:
/opt/vmware/player/bin/vmware-config.pl.

Nano syntax highlighting for Bash

Bram Schoenmakers — Thu, 29 Nov 2007 17:07:51 +0100

It's not something which you see on first sight, but nano does support syntax highlighting. Have a look in /usr/share/nano and there you'll see some files which define rules for syntax highlighting. Now, to enable C highlighting in nano, edit your ~/.nanorc file and append the following line:

include /usr/share/nano/c.nanorc

Grab Kopete history from a certain date

Bram Schoenmakers — Mon, 26 Nov 2007 22:19:19 +0100

This contains a quick script for grepping in your Kopete history, spitting out conversations held on a certain date.

Usage: kopetehist [ DAY [ MONTH [ YEAR ] ] ]

If a value hasn't been supplied it will default to the value of the current date.

Nothing special, but just wanted to share it.

Settings up NFS from a FreeBSD client to a Linux server

Bram Schoenmakers — Sat, 24 Nov 2007 19:28:10 +0100

I think it won't ever happen to me that NFS will 'just work'. During the process of getting server and client work together, you'll almost always encounter at least one permission denied, go to hell.

svnserve listening for incoming connections over IPv6

Bram Schoenmakers — Fri, 23 Nov 2007 12:05:59 +0100

By default, when you start the SVN server, svnserve, it listens on a port via the IPv6 protocol. This means you cannot connect to the server when approaching it with a xxx.xxx.xxx.xxx (IPv4) address.

You can solve this by adding the following parameter to the svnserve call:

# svnserve --listen-host 0.0.0.0

You should supply this in the configuration file taking care of starting svnserve.

PEAR upgrade fails due to tmp directory permissions

Bram Schoenmakers — Thu, 22 Nov 2007 22:25:47 +0100

While upgrading the PEAR port from 1.6.2 to 1.6.2_1 in FreeBSD, I got the following error:

Getting track info from the Last.fm player

Bram Schoenmakers — Wed, 14 Nov 2007 12:59:49 +0100

I'm an addict when it comes to personal status messages in instant messenger protocols. I like to express thoughts, funny things (fortunes) and especially like to use the Now Listening feature. Which I've implemented differently than the Kopete media plugin, to suit my needs.

However, the script was only able to extract info from my favorite music player, Amarok. It couldn't show what I was playing when I was listening to my Last.fm.

Last.fm Player installation on Debian

Bram Schoenmakers — Tue, 30 Oct 2007 22:53:51 +0100

Debian is not (yet) my number one Linux distribution, and because of that I'm not really familiar with the procedures to do things cleanly regarding packages.

Some time ago I tried to install the Last.fm Player on a Debian system.

Enabling GMailFS on a Gentoo Linux system

Bram Schoenmakers — Mon, 29 Oct 2007 22:34:42 +0100

Given the (ever increasing) storage size of a GMail account, it becomes interesting as an alternative backup storage location. The GMailFS project becomes an interesting option then.

Using Gentoo, I referred to Gentoo-Wiki.com where a howto was given on how to install GMailFS. This is a virtual file system, based on the FUSE infastructure. This allows you to enable support for a (virtual) filesystem without having to modify the kernel.

Limiting mail delivery from PHP websites

Bram Schoenmakers — Sat, 27 Oct 2007 16:37:06 +0200

QMail is quite a challenge to set up right, this will take you hours if you don't install it on a weekly basis. When you closed all holes from the outside to prevent acting like a open relay, there is the security on the localhost itself. It happened a few times already that a PHP script had an impromper loop condition which had a mail() call inside. This will guarantee you for having 10.000s of mails in your queue. Or think of a leak in a contact form abused by spammers.

Overriding PHP settings with PHP in CGI mode

Bram Schoenmakers — Thu, 25 Oct 2007 12:42:24 +0200

On a webserver where suexec is active, each website has it's own php-cgi wrapper. The contents are quite simple:

#!/bin/sh
exec /usr/local/bin/php-cgi

Unfortunately, since PHP runs in CGI mode and not as an Apache module, overriding PHP settings is not possible within a .htaccess file. But there's another way of doing this.

SquirrelMail: Unknown user or password incorrect

Bram Schoenmakers — Fri, 19 Oct 2007 14:08:59 +0200

After having solved the problem described in previous entry, I encountered new problems with logging in.

Now, after I entered my credentials, the following error was shown:

Unknown user or password incorrect

The SquirrelMail website suggested that the IMAP server was misconfigured somehow.

SquirrelMail: Could not create initial preference file

Bram Schoenmakers — Fri, 19 Oct 2007 12:55:51 +0200

After a login attempt at the Squirrelmail page I got the following error:

Could not create initial preference file!
/var/spool/squirrelmail/pref/ should be writable by user httpd
Please contact your system administrator and report this error.

passwd broken on Gentoo: "Critical error - immediate abort"

Bram Schoenmakers — Wed, 17 Oct 2007 21:30:13 +0200

When changing a user password I got the error

s040391 bram # passwd
passwd: Critical error - immediate abort

Hmm, something seems to be horribly broken on my Gentoo system. revdep-rebuild didn't show anything useful and re-emerging the 'shadow' package didn't help much either. Luckily, I found on some other site the Gentoo way of fixing this:

emerge -1 cracklib shadow

Et voila, it works again.

FreeBSD gives sigreturn signals inside VirtualBox

Bram Schoenmakers — Fri, 12 Oct 2007 19:03:58 +0200

A few days ago I tried to run FreeBSD in VirtualBox. At first sight all seemed to work well, but as soon as I gave the guest system a little work to do, errors like

sigreturn: eflags 0x80247

popped up on the console.

Fixing SMTP slowness with QMail

Bram Schoenmakers — Fri, 12 Oct 2007 13:10:45 +0200

At some point, an local SMTP server (QMail) responded really slow on connection attempts. There was no traffic between the client and server so it was a bit unclear why it was locked for about 30 seconds until the so-called '220' response.

Google suggested me (indirectly) to disable reverse DNS lookups on the tcpserver (with the -R, -P, -l 'hostname') flags. But that didn't help.

QMail: POP3 bailing out all the time

Bram Schoenmakers — Mon, 01 Oct 2007 15:59:17 +0200

The POP3 server which comes together with QMail had some severe problems: it stopped working after 1 or 2 days. Before that, it worked like a charm, but at some point it just decided to stop accepting incoming calls. The server process didn't die, it was still active and listening on port 110 (according to sockstat -l).

QMail: Prevent relaying with a percent or exclamation mark

Bram Schoenmakers — Wed, 26 Sep 2007 17:59:29 +0200

After setting up a QMail SMTP server, it seems some spammers found a way to relay through our host. Of course, I installed the rcpthosts file with a list of allowed domains, but somehow they got through.

spamc doesn't write spam headers anymore

Bram Schoenmakers — Sun, 16 Sep 2007 13:03:16 +0200

After upgrading to SpamAssassin 3.2.2 and switching to the spamd/spamc construction, all of a sudden spamc didn't write any additional headers to mails.

Run cron.php on a multisite Drupal installation

Bram Schoenmakers — Fri, 07 Sep 2007 18:46:26 +0200

The attached shell script automatically runs cron.php for each site on a multisite Drupal installation. Eventually, put this script in a crontab in order to update all sites on a hourly/daily basis.

Make sure to modify the $DRUPALS variable to your situation.

Mail is not being sent after installing simscan

Bram Schoenmakers — Fri, 07 Sep 2007 17:21:02 +0200

After installing simscan I was no longer able to send any message. The following message was being spitted out upon sending an e-mail through this SMTP-server:

'451 mail server temporarily rejected message (#4.3.0)'

POP3 authentication problems (QMail/VPopMail)

Bram Schoenmakers — Fri, 31 Aug 2007 18:11:04 +0200

Setting up a POP server with the QMail/VPopmail combination wasn't too much hassle until the point I tried to authenticate.

Telnetting into the POP server and giving authenticating myself resulted in the following error:

-ERR authorization failed

Recreating a mail queue in QMail

Bram Schoenmakers — Fri, 31 Aug 2007 12:39:10 +0200

Maybe it was not so smart to do after all to remove all files in the QMail queue while QMail was running.

# qmailctl queue
...
warning: trouble with #173649: file does not exist
warning: trouble with #173741: file does not exist
warning: trouble with #173994: file does not exist
warning: trouble with #174063: file does not exist
...

SVC: file does not exist

Bram Schoenmakers — Fri, 24 Aug 2007 16:21:24 +0200

When trying to start the QMail POP server with the svc command (daemontools), the following error appeared.

svc: warning: unable to control /var/service/qmail-pop3d: file does not exist

The problem got solved by restarting the daemon:

/usr/local/etc/rc.d/svscan.sh restart

Problem with mounting NFS share

Bram Schoenmakers — Mon, 20 Aug 2007 18:42:41 +0200

To me, NFS is like black magic. Getting it to work consists of trial and error and feel lucky afterwards.

The big plan was to use a /usr/ports directory from another machine on the same network. Shouldn't be too hard, right?

Installing FreeBSD on a Compact Flash card

Bram Schoenmakers — Mon, 20 Aug 2007 13:48:44 +0200

When trying to install FreeBSD 6.2 on a 2 GB compact flash card, the following error appeared:

ad2: timeout waiting to issue command
error issuing READ_DMA command ad2

No suitable demux plugin - how to fix

Bram Schoenmakers — Thu, 21 Jun 2007 16:54:00 +0200

From one day to another, my music player Amarok stopped working. It gave me the following notice:

No suitable demux plugin. This often means that the file format is not supported.

Backup solution with rdiff-backup to a FAT disk

Bram Schoenmakers — Thu, 12 Apr 2007 15:00:00 +0200

Some time ago I wrote an article of my backup solution using dar(1). But somehow this started to get itchy because dar is not really a portable format. Whenever something happens to my original files, I need dar in order to restore them. So was basically bound to quite specific tools.

M4A to MP3 conversion

Bram Schoenmakers — Fri, 09 Feb 2007 23:48:00 +0100

Wondering how to convert M4A files to MP3 and convert the tags as well? Look at this script I found on the almighty Gentoo Forums.

Connecting to SSH server on QEmu guest

Bram Schoenmakers — Thu, 08 Feb 2007 23:21:00 +0100

I was wondering how to connect to a SSH server running on a guest computer with QEmu. There wasn't really an obvious way to do that, until I looked at the help text a bit closer:

-redir [tcp|udp]:host-port:[guest-host]:guest-port
redirect TCP or UDP connections from host to guest [-net user]

So starting QEmu with the following parameters did the trick:

$ qemu ... -redir tcp:2222::22 &

Now connecting is a piece of cake:

$ ssh -p 2222 localhost

Skipping files with dump(1)

Bram Schoenmakers — Sat, 13 Jan 2007 00:20:00 +0100

In order to decrease our backup size we decided to skip some files and directories which were not critical. With chflags(1) you can skip entire directories:

chflags -R nodump mydir

Broken network in Debian

Bram Schoenmakers — Wed, 10 Jan 2007 00:44:00 +0100

I must say I'm impressed with Debian so far. It still has not convinced me to drop Gentoo and start using Debian, Gentoo is simply too cool for that.

With both distro's it's always a bit iggy what will happen if you do emerge world or apt-get upgrade respectively. Most of the times things go well and you have an up-to-date system. Sometimes things go wrong.

Top of the tops

Bram Schoenmakers — Thu, 07 Dec 2006 22:36:00 +0100

Last weekend, while I joined the first edition of the T-Dose conference at the university of Eindhoven, a talk was given about atop.

Dump/restore fun

Bram Schoenmakers — Thu, 07 Dec 2006 15:52:00 +0100

Situation: a FreeBSD webserver needs a backup system. dump and restore are your friends then. Restoring all that data is not that trivial, if you don't know how dump operates. But the manpages of these commands should help a lot already.

CCache problems in Gentoo

Bram Schoenmakers — Sun, 19 Nov 2006 19:30:00 +0100

For KDE I regulary build the sources from the SVN repository. I found out by accident that CCache was not taken into account with a manual build, it only seemed to work when I issued an emerge command.

Number of compile jobs

Bram Schoenmakers — Sat, 18 Nov 2006 21:54:00 +0100

I did a little experiment with n parallel compile jobs, with the famous -j flag for make. The reasoning behind all this is that a single process gets regularly blocked by retrieving data from disk, which is relatively slow.

I compiled the KDE PIM 3.5.5+ feature branch (revision 605781) with unsermake (a somewhat more efficient of the automake/make tools).

Stripping Amarok memory usage

Bram Schoenmakers — Sat, 18 Nov 2006 12:21:00 +0100

I was interested in which shared libraries are in my system's memory. The following command produces such a list:

# lsof | awk '{print $9}' | grep \\.so | sort -u

I had some trouble with the following line in the output:

/usr/lib/opengl/ati/lib/libGL.so.1.2

KDM Auto Login

Bram Schoenmakers — Sat, 18 Nov 2006 11:56:00 +0100

This is what I already wrote on my KDE blog, but I think it's worthwile to note it down here as well:

FCron: schedule command almost each day on different intervals

Bram Schoenmakers — Thu, 16 Nov 2006 00:26:00 +0100

With fcron I couldn't find a way to enter a command with the following schedule: run daily, except on each first of the month, a command between 5am and 7am or between 6pm and 10pm.

Know where your keys are

Bram Schoenmakers — Sat, 11 Nov 2006 01:03:00 +0100

SSH can be funny to set up, it's easy to do something wrong. Some time ago I had to help a customer with setting up a SSH connection to our webserver, which only allows public key authorization.

Error message:

Permission denied (publickey)

We retried about everything. The problem was not server side, the keys were generated according to our instructions (as far as we could check), the permissions to the keys were OK, no incompatibilities with the Mac version of openssh and our FreeBSD server. Everything was OK, except...

Gentoo: checking useflags for each installed package

Bram Schoenmakers — Mon, 19 Jun 2006 04:00:00 +0200

If you're wondering, as a Gentoo user, whether your installed packages use the right USE flags, this script may be useful. Either you wonder "why the heck has foo been built with bar support?" or "why the heck has this not been included with the build, I really need bar!". When you see useflags for a package which don't suit your needs, adapt /etc/portage/package.use (or even /etc/make.conf).

Here's the script (depending on gentoolkit).

Enabling Last.fm links in Konqueror

Bram Schoenmakers — Mon, 16 Jan 2006 22:33:00 +0100

This HOWTO describes briefly how to enable Last.fm Player support for the Konqueror webbrowser.

Download the attached protocol file.
Edit this file and edit the line with

exec=/path/player "%u"

so that it points to your Last.fm player executable. Leave the %u part!
Put the protocol file in ~/.kde/share/services