X11 Forwarding Fails When IPv6 is Disabled [Resolved]

After disabling Ubuntu 11.10′s IPv6 by putting the following lines in /etc/sysctl.conf, I found that X11 Forwarding (ssh -X option) stopped working.
#Disable IPv6
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1

Ubuntu Forum had an exact same case and workaround.

http://ubuntuforums.org/showthread.php?t=1649657

So, I put the following lines in remoet host’s /etc/ssh/sshd_config file.

$ cat /etc/ssh/sshd_config

………………………………

# Workaround to have X forwarding work when ipv6 is disabled
# http://ubuntuforums.org/showthread.php?t=1649657
AddressFamily inet

————-

It worked.

Linux rdesktop (Remote Desktop) with ClearType font smoothing enabled

I was looking for ways to make fonts look better in connecting to Windows from Linux via rdesktop.

The following page shows a great resolution/workaround.

http://katastrophos.net/andre/blog/2008/03/10/rdesktop-connect-to-windows-vista-with-cleartype-font-smoothing-enabled/

$ rdesktop -u mywinusername -k en-us -g 93% -x 80 -r sound myhostipaddress

Two other options than -x 80 are shown in the page above, -x 81 and -x 8f.  (Refer to the page above.)

 

 

Maven 2.2.1 – [WARNING] repository metadata for: ‘org.apache.maven.plugins’ could not be retrieved from repository

On Maven 2.2.1, I had trouble when executing, “mvn archetype:generate”, with the following errors.

[INFO] Searching repository for plugin with prefix: ‘archetype’.
[INFO] org.apache.maven.plugins: checking for updates from central
[WARNING] repository metadata for: ‘org.apache.maven.plugins’ could not be retrieved from repository: central due to an error: Error transferring file: Connection timed out
[INFO] Repository ‘central’ will be blacklisted

Finally, it turned out that the proxies section in settings.xml was not commented/uncommented properly. Windows XP Firewall or security software had nothing to do with the error.

Trang – Multi-format schema converter based on RELAX NG

Trang is a schema converter.

Install Trang on Ubuntu 10.04 LTS.
$ sudo apt-get install trang

This time, I used Trang to generate an XSD file from an XML file.

$ trang -I xml -O xsd InputXmlFile.xml OutputXSDFile.xsd

CVS Server Installation on Ubuntu Linux 10.04

I installed CVS Server on Ubuntu 10.04.
CVS repository is copied from another machine, and it is placed in /opt/cvsroot .

Reference:
https://help.ubuntu.com/10.04/serverguide/C/cvs-server.html

# apt-get install xinetd
# apt-cache search git-cvs
# apt-get install git-cvs
# apt-cache search cvsps
# apt-get install cvsps

Edit /etc/xinetd.d/cvspserver .

# vi /etc/xinetd.d/cvspserver

The file now looks:

# cat /etc/xinetd.d/cvspserver
service cvspserver
{
port = 2401
socket_type = stream
protocol = tcp
user = root
wait = no
type = UNLISTED
server = /usr/bin/cvs
server_args = -f –allow-root /opt/cvsroot pserver
disable = no
}

# /etc/init.d/xinetd restart

Ensure CVS server is running.

# netstat -tap | grep cvs
tcp 0 0 *:cvspserver *:* LISTEN 11676/xinetd

Ubuntu Screen Resolution on Toshiba Satellite Pro 4600 with Trident XP

I installed Ubuntu Linux 10.04 on Toshiba Satellite Pro 4600 with Trident XP 16MB video, which is about 10 years old.
At first, the screen resolution was 800×600 on 1024×768 LCD.

Finding the following entry, I made /etc/X11/xorg.conf as shown below.
http://ubuntuforums.org/showthread.php?t=1354952

Then, the screen resolution became 1024×768.

$ cat /etc/X11/xorg.conf
Section “Monitor”
Identifier “Configured Monitor”
Option “DPMS” “true”
HorizSync 30.0-60.0
VertRefresh 50.0-70.0
EndSection

Section “Screen”
Identifier “Default Screen”
Monitor “Configured Monitor”
Device “Configured Video Device”
DefaultDepth 24
SubSection “Display”
Depth 24
Modes “1024×768″ “800×600″
EndSubSection

EndSection

Using AirTunes-AirMac Express from Ubuntu Linux

Install pulseaudio-module-raop
$ sudo apt-get install pulseaudio-module-raop

Install paprefs
$ sudo apt-get install paprefs

$ paprefs
In “Network Access Tab”, check both:
Make discoverable PulseAudio network sound devices available locally
Make discoverable Apple AirTunes sound devices available locally

System’s sound setting allows you to choose AirTunes sound device as output.

cron-like job setting on Windows XP with schtasks command

Task Scheduler GUI on Windows XP does not appear to allow us to set a job every 5 minutes.

Instead, schtasks command allows cron-like setting.

To set a job (a batch file) to run every 5 minutes, here’s a sample command.

C:\>schtasks /Create /SC MINUTE /MO 5 /TN yourjob_every5min.bat /TR C:\yourfolder\yourbatchfile.bat

Grub Error 18 – Debian Linux 5.05 (Lenny)

When I installed Debian 5.05 (Lenny) onto a machine with an old motherboard, ASUS CUSL2-C (2000 or 2001 model), I got the following Grub error.

Grub Stage 1.5

Grub Loading, Please Wait
Error 18

My initial configuration was to use an entire HDD (one partition for the mountpoint / and another for swap).

According to the web page below, I made a separate /boot partition with 200MB, from the root (/) partition, placing the /boot at the first partition (/dev/hda1) of the HDD.

Then, base system installation was completed with GUI installation and Debian was successfully booted.

http://www.linuxquestions.org/questions/linux-hardware-18/grub-loading-please-wait-error-18-a-343280/

Motherboard: ASUS CUSL2-C (BIOS 1009, which is the latest release)
HDD: Hitachi HTS541616J9AT00 (160GB)

Incidentally, with this motherboard with Matrox G400 Video card, X window was not configured properly, and I am still researching.

Hadoop Installation Note (Standalone)

This is a note when I installed Hadoop on a single machine (standalone).

I followed Hadoop Quick Start available at:
http://hadoop.apache.org/common/docs/r0.20.0/quickstart.html

Check Java version — Java 1.6.x is required, and Sun version is preferred. See:
http://hadoop.apache.org/common/docs/r0.20.0/quickstart.html

Download hadoop-0.20.2.tar.gz from:
http://hadoop.apache.org/mapreduce/releases.html#Download

$ tar xvzf hadoop-0.20.2.tar.gz

Skip rsync and ssh installation, as they are already available on the machine.

// Check the command usage:
$ cd hadoop-0.20.2
$ bin/hadoop
Usage: hadoop [--config confdir] COMMAND
where COMMAND is one of:
namenode -format format the DFS filesystem
secondarynamenode run the DFS secondary namenode
namenode run the DFS namenode
datanode run a DFS datanode
dfsadmin run a DFS admin client
mradmin run a Map-Reduce admin client
fsck run a DFS filesystem checking utility
fs run a generic filesystem user client
balancer run a cluster balancing utility
jobtracker run the MapReduce job Tracker node
pipes run a Pipes job
tasktracker run a MapReduce task Tracker node
job manipulate MapReduce jobs
queue get information regarding JobQueues
version print the version
jar run a jar file
distcp copy file or directories recursively
archive -archiveName NAME * create a hadoop archive
daemonlog get/set the log level for each daemon
or
CLASSNAME run the class named CLASSNAME
Most commands print help when invoked w/o parameters.

$ mkdir input
$ cp conf/*.xml input
$ bin/hadoop jar hadoop-*-examples.jar grep input output ‘dfs[a-z.]+’
Error: JAVA_HOME is not set.

$ /usr/java/latest/bin/java -version
java version “1.6.0_16″

$ export JAVA_HOME=/usr/java/latest
[added this line in the .bashrc]
Reference: http://www.atmarkit.co.jp/fjava/special/distributed03/distributed03_1.html

Try again:
$ bin/hadoop jar hadoop-*-examples.jar grep input output ‘dfs[a-z.]+’

No error message is shown this time.
$ cat output/*
1 dfsadmin