How To ..

Reset Compiz in Ubuntu 11.04

2011-07-10T04:56:00.000-07:00

If your window title bar is gone. or you have messed the compiz in any other way in Ubuntu. Just open up a terminal and enter the following command:

gconftool-2 --recursive-unset /apps/compiz-1

Solve -- Xlib: extension GLX missing on display

2011-07-10T03:58:00.000-07:00

Recently I was playing with OpenCL in my system. Due to its dependency, I had to mess up with different packages. I even installed Intel® OpenCL™. And suddenly on next boot Something went wrong.
And this is what I did to revert back:

sudo apt-get purge nvidia*
sudo apt-get install --reinstall xserver-xorg-video-intel  libgl1-mesa-glx libgl1-mesa-dri xserver-xorg-core
sudo dpkg-reconfigure xserver-xorg
sudo update-alternatives --remove gl_conf /usr/lib/nvidia-current/ld.so.conf

Hope it helps you too.

Reference:
https://theiszm.wordpress.com/2010/06/27/glx-missing-on-display/

Save Streamed Flash Video [Firefox-4] [Linux]

2011-06-26T06:46:00.000-07:00

It cost me almost half an hour to find the location, where Firefox saves the streamed video. And I made a script for it as I often need it. Here's the script, hope it helps you:

file /proc/$(pidof npviewer.bin)/fd/* | grep -i "flash" | \
  cut -d':'  -f1 | xargs -i{} cp {} ./

Details of what the command will do:
Fifefox-4 uses an external process (npviewer.bin) to manage external plugins. So what I did was grabbed a copy of the deleted flash file (yea it deletes the file, but keeps a secret opening for itself) from npviewer.
Finally all the cached video are copied to current path named with some random numbers (technically, the number is file-descriptor).

Warning: Execute the command after complete streaming and before closing the firefox(-tab).

Nikon Intervalometer using Nepaluino (Arduino)

2011-04-04T08:28:00.000-07:00

Recently I got a chance to attend the first Nepaluino workshop (Sincere thanks to Ujwal Shrestha). It was real fun to program Nepaluino with hackers.
For those who don't know what Nepaluino is: its a Arduino clone. More on this from the founder of Nepaluino -> here

Few days after that we decided to build Intervalometer using Nepaluino. As I own a Nikon D90, I set myself to build one for it. Thanks for the help, Ujwal.

So lets start.
First connect the Circuit. Its pretty easy Just connect the Nepaluino digital pin-13, the IR transmitter, the register and the Ground in series.

Next compile the following code in Arduino IDE and upload to Nepaluino.

/*
LUCKYLARRY.CO.UK - IR Remote control for Nikon using Arduino
Mimics the infrared signal to trigger the remote for any Nikon camera
which can use the ML-L1 and ML-L3 remotes. Can be used as an intervalometer
for time lapse photography.
The IR sequence I used is originally taken from: http://www.bigmike.it/ircontrol/
You should be able to use my pulse methods to alter to suit other cameras/ hardware.
micros() is an Arduino function that calls the time in Microseconds since your program
first ran. Arduino doesn't reliably work with microseconds so we work our timings by
taking the current reading and then adding our delay on to the end of it rather than rely
on the in built timer.
*/
int pinIRLED = 13;                                      // assign the Infrared emitter/ diode to pin 13
void setup() {
  pinMode(pinIRLED, OUTPUT);                            // set the pin as an output
}
// sets the pulse of the IR signal.
void pulseON(int pulseTime) {
  unsigned long endPulse = micros() + pulseTime;        // create the microseconds to pulse for
  while( micros() < endPulse) {
    digitalWrite(pinIRLED, HIGH);                       // turn IR on
    delayMicroseconds(13);                              // half the clock cycle for 38Khz (26.32×10-6s) - e.g. the 'on' part of our wave
    digitalWrite(pinIRLED, LOW);                        // turn IR off
    delayMicroseconds(13);                              // delay for the other half of the cycle to generate wave/ oscillation
  }
}
void pulseOFF(unsigned long startDelay) {
  unsigned long endDelay = micros() + startDelay;       // create the microseconds to delay for
  while(micros() < endDelay);
}
void takePicture() {
  for (int i=0; i < 2; i++) {
    pulseON(2000);                                      // pulse for 2000 uS (Microseconds)
    pulseOFF(27850);                                    // turn pulse off for 27850 us
    pulseON(390);                                       // and so on
    pulseOFF(1580);
    pulseON(410);
    pulseOFF(3580);
    pulseON(400);
    pulseOFF(63200);
  }                                                     // loop the signal twice.
}
void loop() {
  takePicture();                                        // take the picture
  delay(5000);                                          // delay in milliseconds which allows us to do timelapse photography - 1 second = 1000 milliseconds
}

Thats it. Now your Intervalometer is ready. It clicks the shutter every 5 secs.Notes:Compatible with: All Nikon Cameras supported by ML-L3Ref: Arduino – IR remote/ intervalometer for Nikon D80 DSLR

Connect to internet using Ncell Connect (E1550)

2010-10-10T06:06:00.000-07:00

First of all sincere thanks to Amit for providing me his Ncell-Connect dongle to try it out in linux.

Ncell has recently launched a data service in Nepal called Ncell Connect. Ncell provides E1550 dongle to to its user. E1550 is uses a Switchable USB Device (storage cum serial device).
In linux, it is detected as storage device only, and one, need to switch the device to modem mode.
So here's, how to install it in ubuntu(linux).
1. Install "usb-modeswitch"
2. Instruct Udev to call mode-switcher whenever the device is plugged in:
Update: Command to switch to root Privilege added.

sudo -s
apt-get install usb-modeswitch
cat > /etc/udev/rules.d/99-ncell-connect.rules <<EOT
# Ncell Connect switch mode to usbserial (E1550 device id => 12d1:1446)
SUBSYSTEM=="usb", ATTRS{idProduct}=="1446", ATTRS{idVendor}=="12d1", RUN+="/lib/udev/modem-modeswitch --vendor 0x12d1 --product 0x1446 --type option-zerocd"
EOT

3. Insert the device.
4. Create a new "Mobile Brodband" connection
4.1 Goto System->Preferences->Network Connections
4.2 Goto "Mobile Brodband" Tab

4.3 Create a new "Mobile Brodband" connection, following are the details that you require:
Device: HUAWEI Technology HuAWEI Mobile [if the list is empty, you messed up Something wrong, Restart from step 1]
Country: Nepal
Service Provider: Ncell
APN: web
Number: *99#
Leave other fields empty.

That's it. Enjoy!!
Happy Dashain

Convert ascii text to hex in linux (bash)

2010-06-09T05:09:00.000-07:00

If you want to convert your ascii text to hex, fire up the bash-terminal and enter the following command:

$ echo -n 'text' | xxd -ps | sed -e ':a' -e 's/\([0-9]\{2\}\|^\)\([0-9]\{2\}\)/\1\\x\2/;ta'

solve temporary file issue with amavis

2010-03-02T04:45:00.000-08:00

Problem:
amavis[6872]: (!!)TROUBLE in process_request: Can't create file /var/lib/amavis/tmp/amavis-20100302T122841-06872/email.txt: File exists at /usr/sbin/amavisd-new line 4856

Solution:

 # perl -MCPAN -e shell;
 cpan> install File::Temp

Format Numbers to be Comma Separated

2009-12-23T22:00:00.000-08:00

I have a number 1234567890, and I want to insert a comma at the gap of three digits like this:1,234,567,890

If this is the problem running in your head then the following one liner will be helpful to you.

$ echo "1234567890" | sed -e ':a' -e 's/\(.*[0-9]\)\([0-9]\{3\}\)/\1,\2/;ta'
1,234,567,890

Convert VOB to AVI using ffmpeg

2009-12-15T09:18:00.000-08:00

Suppose you have a myVideo.vob and you want to convert to avi format.
Open a terminal and execute the following command

$ ffmpeg -i myVideo.vob myvideo.avi

Possible errors:
1 "ffmpeg: symbol lookup error: ffmpeg: undefined symbol: avcodec_channel_layout_num_channels"
Solution:

$ export LD_LIBRARY_PATH=/usr/local/lib/ && ffmpeg -i myVideo.vob myvideo.avi

If this doesnt solve the problem then retry that after installing the libavcodec52 and libavutil49 packages:

$ sudo apt-get install libavcodec52  libavutil49

Bulk upload photos to facebook [BASH]

2009-09-29T21:36:00.000-07:00

I got tired of uploading one photo at a time. So I googled a bit, and found few scripts but none did convince me. So I set to write one by myself. And my focus was to keep it short and simple(KISS).

The tool is a python script with following features:
* Bulk upload the pictures to facebook.
* Supports upload from specified folder or current folder (default).
* Allows to choose from available albums.

Usage:
upload2facebook [-a|--aid <album_id>] [<path>]

Install:
(Don't forget to read the notes below)
In Debian (Ubuntu, Kubuntu,...) system:
1. Install from ppa https://launchpad.net/~ssapkota/+archive/ppa
2. Install directly from deb-package -> upload2facebook_0.2_i386.deb , Package Detail

In RPM (Fedora, Centos) system
3. Install the rpm -> http://ssapkota.com.np/downloads/upload2facebook-0.2-2.i386.rpm

4. Get the source, do whatever you like -> upload2facebook_0.2.tar.gz

Note-1:
During the installation of this tool, it will ask you to enter the Application Key and Application Secret Key. To get this two key you need to register an application for yourself at facebook. Follow the following (necessary) steps:
1. Go to http://www.facebook.com/developers and click on Setup Up New Application at the top right corner.
2. Enter the Application Name (I suggest : Photo Uploader)
3. Then click Agree and then Save Changes
4. After this you will get API Key and Secret. Copy it and save it somewhere; you'd need later. Remember, these keys are meant to be secret and shouldn't be shared (So, did I ;) ).
5. You need to do one more thing to make it work; On the left-navigation click on the Canvas and then enter a URL(may be your website/blog link) as Canvas Callback URL. I don't think this is of any use for command line application, but to make the application work you need to set this.
6. Thats it. Return to the installer and Enter your App Key and App Secret.

Note-2:
1. The tool is developed and tested in Ubuntu and works in all the Debian system.
2. The RPM package is generated using alien and have not been tested.
3. The code is written in python and is OS independent, One can easily port to any other Operation system.
4. If you have tested the tool in other system or have ported it to other OS, please post the status in the comment.

Enjoy the tool. :)

Verify IPV4 address in php using regex

2009-06-29T00:48:00.000-07:00

A simple function in php to verify IPV4 Address. It is completely based in regex and does full ip verifying.
It tests the ip for;
1. Need 4 numeric blocks separated by a dot.
2. Each numeric block must noot exceed 255.
3. Shouldn't contain space. So remember to trim before calling this function.


function isINetAddress($ipaddr){
if( preg_match( "/^((?:25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9]).){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])$/m",$ipaddr) > 0)
 return true;
}

This can't me more simpler. ;)
Enjoy!

Bluk rename files in Linux

2009-05-24T03:21:00.000-07:00

Today one of my friend asked me to bulk rename all files in a folder. He had a collection of songs named randomly with no extension. He also wanted to add the extension, mp3 in all files(Yes, he was sure about the encoding)
I opened a terminal in that folder and executed the following command.

NUM=1
for SONG in ./*
do
mv $SONG song$NUM.mp3
let NUM=NUM+1
done

So lets peek what the above script does:

Defined a variable NUM and initialized it with 1.
Defined a foreach loop. Here for each files in current path the for loop is executed.
Rename(move) the file $SONG to song<num>.mp3
Increase the value of variable NUM by 1.
end. ;)

So if you want to rename in a different fashion you can hack the line mv $SONG song$NUM.mp3 in any way you like. But Remember the second argument to the mv command must vary for each loop, otherwise you will end up deleting all files except the last one.

Solve no sound problem in Ubuntu

2009-05-11T09:11:00.000-07:00

One after another 17 days have passed.. till today my laptop was completely silent when i booted into Ubuntu. But now, just 10 mins back, after a lot of hit and trial with driver model, I could make make my laptop speak. Here's what I did.
Though I specified this as ubuntu problem in title, it the problem of alsa; it's not recognizing your device.

I completely forgot what I did to mess up my laptop-sound-system, so i thought to start afresh.
I removed the alsa and pulseaudio completely. And One thing I would like to mention: I am completely unfamiliar about the interaction of alsa and pulseaudio with the sound system. This is my first deal with sound system of linux to this depth.

sudo apt-get --purge remove linux-sound-base alsa-base alsa-utils \
       "pulseaudio-*"

Then I did a quick Reboot; just playing safe. (Jaunty boots on/off so fast, I am fan of it.)
Next I reinstalled the alsa with pulseaudio.

sudo apt-get install linux-sound-base alsa-base alsa-utils \
       libasound2-plugins "pulseaudio-*" paman padevchooser \
       paprefs pavucontrol pavumeter

Then, I appended following lines to the file /etc/modprobe.d/alsa-base.conf

alias snd-card-0 snd-hda-intel
alias sound-slot-0 snd-hda-intel
options snd-hda-intel model=dell-m6
options snd-hda-intel enable_msi=1

The bold faced "model=dell-m6" was the main hack for the system to work.

Then after another quick boot, I got the sound.

During this I refered a lot of pages, But the most useful and the one that is well documented is: Comprehensive Sound Problem Solutions Guide
And this is the page where I got the model of the sound-card(dell-m6) from.

Utilize Grep Sed and Awk

2009-04-30T06:32:00.000-07:00

In this post I will list commands that I use and include at least one of grep,sed or awk.

cat filename | grep "phrase"
Search line containing phrase in file
cat filename | grep -v "phrase"
Search line not containing phrase in file
cat filename | grep "phrase1\|phrase2"
Search lines containing phrase1 or phrase2 in file.
sed -i "s/phrase1/phrase2/g" ./filename
Replace phrase1 with phrase2 in file.
sed -i "s/[ ]*$.*$[ ]*/\1/g" ./filename
Trim spaces of each line of the file.
awk '{if($7=="2") $7="5"; print;}' file
Conditional modification. Field no.7 is is replaced by "5" if it is "2". The default field seperator is .
uptime | awk 'BEGIN {FS=" "} { gsub(",",""); if (index($0,"day")) {gsub(":"," hours, ",$5);print $3" "$4", "$5" minutes"} else {gsub(":"," hours, ",$3); print $3" minutes"}}'
Get the Uptime in a proper and clear format.
ls | grep -v 'file or folder or regex' | xargs -I{} mv {} /target/folder/
Move all but one to /target/folder. You can also use it to move all the files/directories in current directory to another directory in the same path.Be Aware: The Target directory should exist. Just to be at the safe side, I suggest not to miss the slash (/) at the end. This will give you warning/error if you messed up something.

For now I have just listed few that came in my mind; just thought to prepare a seed.
I'll promise to grow this list as soon as they come to my mind.

Note: If you have some commands in your mind, that you regularly use, plz post it as comment.

make scite, a default editor in gnome

2009-03-24T06:38:00.000-07:00

Personally, I prefer scite over gedit (The one that is included by default in gnome). So soon after every system upgrade (fresh installation), I simply remove gedit and install scite:

sudo sh -c "apt-get -y remove gedit && apt-get -y install scite"

Now to make it a default text editor run:

sudo update-alternatives --install /usr/bin/gnome-text-editor \
    gnome-text-editor /usr/share/scite 1

Terminal tool for websms (NTC service)

2009-02-17T06:58:00.000-08:00

Websms is a service provided by NTC.
It is service that allows us to send 10 SMS per day via its web-interface.

Each time when I need to send a SMS, I had to open the site,login(no auto remember facility) and send SMS. So I thought to create a tool that would save time.

You can download the debian package from here: websms_1.01_all.deb

Install it using:
dpkg -i ./path/to/websms_1.01_all.deb

Synopse:
websms help
This displays the help for this tool.

websms addcontact <nick> <Mobile Number>
You can store the mobile number with (nick)name in the contacts list. Later you can use the (nick)name to send SMS to him/her.

websms viewcontacts
You can view the complete list of your contacts.

websms send <nick | Mobile Number> <Message>
Send the SMS by Mobile Number or by (nick)name that you stored earlier.The message length cannot exceed above 142.

Examples:

$ websms addcontact sweety 98********

$ websms send sweety "I will be late."

$ websms send 98******** "Call me back. --suraj"

$ cat joke | websms send 98********

Be sure that the size of file "joke" doesnt exceed 142 bytes.

$ websms viewcontacts

Enjoy!

Note:The secure-info and the contact-list are located in ~/.websms directory.

EDIT:
On the request of you Guys I have added the RPM package too:
Direct Download Link:websms-1.01-2.noarch.rpm
[Note:The RPM package was generated with alien.]

Search with single click

2009-01-05T11:24:00.000-08:00

Searching cant be any more easy than this.Just select and click.
Here is how you can search anything you select with just a single click.
First install this package "googlizer"
apt-get install googlizer

Just drag it to the panel(from Applications->Internet) for easy access and enjoy.
Select any text anywhere and just click on it.

You can even use it with other links.. May be answers.com or wikipedia.org. Here's, how you do it.

Right click on the googlizer button on the panel and open its properties. And in the command text area type the following to convert it to answerizer ;)

googlizer -u "http://www.answers.com/topic/"

If you want to look it better click on the googlizer Icon at the top left of the properties dialog and change it as you want.

The core thing that the googlizer does is just copies the text in X'selection and appends it to the end of the link that you provide, and finally opens it in Browser. If you do not provide any link then it uses "http://www.google.com/search?q=".

For Wikipedia-izer, whatsoever,

googlizer -u "http://en.wikipedia.org/wiki/"

*Please leave in comment if you use it for any other.

gegls in Ubuntu

2008-12-28T13:17:00.000-08:00

Got to know about this easter-egg-thing in ubuntu.

A virtual Easter egg is an intentional hidden message or feature in an object such as a movie, book, CD, DVD, computer program, web page or video game.

This is just a funny hidden game.
Open the Run application Dialog using ALT + F2 and then type "gegls from outer space" without the quotes and then just hit Enter.

The game pops up.
Screenshot:

Enjoy the game!

Got it from ester egg archive.

Schedule a job in cron

2008-12-17T10:36:00.000-08:00

For the task that you have to run regularly in some period, scheduling it in the cron is the one and only way for it.
For this run this in terminal:
crontab -e

This will start the vi editor and load the current cron table file for this user, or a blank file if none exists. In a new line type the following

A B C D E < path to the script > [Arguments if any]

Where:

A = minute of the hour

B = hour of the day

C = day of the month

D = month of the year

E = day of the week

Example:
To schedule a Task daily at 9 in the moring that lies in /home/sata/script. I use the following.

0 9 * * * /home/sata/script

solve "Communications link failure" in matlab

2008-11-15T11:25:00.000-08:00

Recently while i was working on my project in matlab. I got the following error.

Connection failed: Communications link failure

Last packet sent to the server was 0 ms ago.
??? No constructor 'com.mathworks.toolbox.database.closeTheDatabaseConnection' with matching
signature found.

After I lost 2 hrs of my time, I remembered I had gone through the same error in Hibernate/mysql.

The solution is so simple:
Just comment out the following line in my.cnf(the mysql configuration file). :)

skip-networking

so that it looks like this:

#skip-networking

Finally restart the service mysql.

To know why see my earlier post:http://howtoxyz.blogspot.com/2008/09/solve-commysqljdbccommunicationsexcepti.html

Run GUI application as another user.

2008-11-11T23:59:00.000-08:00

I knew that if there is some flaw in irc-client it will leave a security loop in the system. And the attacker get the privilege of the user running the irc-client. And you know what it will lead to.
So specially to run the X-chat (a irc client), I created another user irc with very less privilege.

Then I tried running the xchat as follows:

suraj $ su irc
Password:
irc$ xchat
No protocol specified

(xchat:6966): Gtk-WARNING **: cannot open display: :0.0

Hum.. There occured a problem. The app couldn't get handle to the grapics display.

So here is the solution:

$ sudo apt-get install sux

and run

$ sux irc xchat
Password:

Provide the password of the user irc and see the application launching.

Disable root ssh login

2008-10-30T21:38:00.000-07:00

Disabling ssh is one of the major security enhancement. It is just a simple task. What you need to do is edit a file ("removing a #") and restart the service. Here it goes,
First you need to find the following line and remove the comment from the file "/etc/ssh/sshd_config".

#PermitRootLogin no

ie. Just remove the preceding "#"

You can edit it in your favorite editor. But remember you need to be have root access to edit it.

Or simply you can run the following command from terminal
sudo sed -i "s/#PermitRootLogin/PermitRootLogin/g" /etc/ssh/sshd_config

Now, For this to take effect, you need to restart the service:
sudo /etc/init.d/sshd restart

reset mysql root password

2008-09-29T14:11:00.000-07:00

Recently, one person left me in his system to solve one of his problem associated with webservice.
He left me and went somewhere and asked me to solve the problem before I left.

During this i requited the mysql root password, but he want there. So i googled to reset the mysql password. And here is what i did to reset the password.

$ sudo /etc/init.d/mysql stop

$ sudo mysqld_safe --skip-grant-tables --user=root

$ sudo mysql -u root

Run this query in mysql prompt:

mysql> UPDATE mysql.user SET Password=PASSWORD('newpassword') WHERE User='root';
mysql> FLUSH PRIVILEGES;

Finally kill this mysql process and restart it safely:

$ sudo /etc/init.d/mysql start

ref: http://www.linuxweblog.com/blogs/sandip/20060330/reset-mysql-root-password

solve "com.mysql.jdbc.CommunicationsException"

2008-09-28T01:14:00.000-07:00

This is the error that I got when trying to connect to mysql (of lampp package, yes in linux) using Hibernate in java.

WARN 2008-09-28 13:55:17,116 org.hibernate.cfg.SettingsFactory -s Could not obtain connection metadata
com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception:

** BEGIN NESTED EXCEPTION **

java.net.ConnectException
MESSAGE: Connection refused

STACKTRACE:

java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:519)
at java.net.Socket.connect(Socket.java:469)
at java.net.Socket.(Socket.java:366)
at java.net.Socket.(Socket.java:209)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:256)
at com.mysql.jdbc.MysqlIO.(MysqlIO.java:271)

Basically, the problem here is because of jdbc connector, which was unable to connect to the database. There are two ways of communication with mysql in linux.

Don't listen on a TCP/IP port at all, if all processes that need to connect to mysqld run on the same host. There interaction with mysqld are made via Unix sockets or named pipes which is .sock file.

B. Simply listen on a TCP/IP port. This allows remote communication to the database too.

Lampp initial configuration sets the first method of communication. And the sock file is created in < lampp root dir >/var/mysql/mysql.sock . But by default the jdbc search it in "/var/run/mysql/mysql.sock" (somewhere like this). Due to this problem, jdbc wont be able to connect to the database.

There are many ways to solve this:
The simple one is to switch to second type of communication method.
find the following line in <lampp root dir >/etc/my.cnf

skip-networking

and comment it.

# skip-networking

Hope this helps you out.

Change your terminal prompt (bash)

2008-08-08T13:57:00.000-07:00

I always get messed up with the output and the prompt. I wanted to so sth that would make the prompt distinguishable. I also hate the (increasing) length of prompt ie showing the full current path.

Ok here's what and how I did. It easy and a bit tricky.

You must have known that while starting a (bash) terminal, the terminal itself runs the script in the "~/.bashrc" file. If you didnt know, know it now.

Ok. Its straight forward, what we do now is add few lines to the end of the file. So open the file in any editer you like and add the following line at the end of the file

BLUE=$(tput setaf 4)
BOLD=$(tput bold)
RESET=$(tput sgr0)
PS1="\[$BLUE\][\u@\h]\[$RESET\] "

Here the env variable PS1 is the normal terminal prompt. FYI PS2 contains the continuation prompt in bash.
So what this says is "DISPLAY A PROMPT IN BLUE COLOR SHOWING [USERNAME@HOSTNAME] AS PROMPT".

Here is the screenshot of my (gnome-)terminal:

Zoomed

EDIT:
Here is a list of Escape Sequence that yuu can use:
http://tldp.org/HOWTO/Bash-Prompt-HOWTO/bash-prompt-escape-sequences.html

Applications menu not working in Ubuntu

2008-07-29T02:31:00.000-07:00

This was the problem faced by Sanaklp, one of my friend. He was trying to install some apps via apt-get. during the installation he was warned about for no space in root partition. Somehow the system was working fine even after all this. But once he rebooted his system, he couldnt see any sub-menu under "Applications" menu. At the moment i reached there and he asked me to resolve the problem.

I thought that some configuration associated with the menu must be wrong and I was right. I just deleted the config file at /home//.config/menus/applications.menu.

$ rm /home/<username>/.config/menus/applications.menu

What happens after you delete this file is the system assumes your menu to be same as the default. Whenever you change the menu (Right click and "Edit Menus"), the system will again generate the file which you deleted earlier.

Relogin and your system must be fine now.

NETDEV WATCHDOG: eth0: transmit timed out

2008-07-22T09:10:00.000-07:00

NETDEV WATCHDOG: eth0: transmit timed out
eth0: Transmit timeout, status 00000004 00000249

This was the error that i got in my kernel log message.

I was unable to use internet in my laptop "MS 1006". I tried setting up the network in either way (dhcp and static) but non of these solved the problem. I got terribly wired, as i could see no other message beside "destination host unreachable" and waiting for never offering, DHCP.

I even wasted 2 days and even googled for many keywords. But i couldnt get the solution. But finally the end of the second day was fruitful. I solved it.

This was due to the interrupt conflict that occured between the acpi and network modules.
I turned off acpi while booting by adding following words at the end of the boot option.

Before:

title Ubuntu 8.04, kernel 2.6.24-16-generic
root (hd0,1)
kernel /boot/vmlinuz-2.6.24-16-generic root=UUID=e89b77d0-3183-4036-b508-15d9a23dc86c ro quiet splash
initrd /boot/initrd.img-2.6.24-16-generic
quiet

After:

title Ubuntu 8.04, kernel 2.6.24-16-generic
root (hd0,1)
kernel /boot/vmlinuz-2.6.24-16-generic root=UUID=e89b77d0-3183-4036-b508-15d9a23dc86c acpi=off ro quiet splash
initrd /boot/initrd.img-2.6.24-16-generic
quiet

Enjoy the net.

ref:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/183588

http://bugzilla.kernel.org/show_bug.cgi?id=7595

Solve [mount_point cannot contain the following characters: newline, G_DIR_SEPARATOR (usually /)]

2008-07-17T00:33:00.000-07:00

I recently suffered from this problem. I googled it and finally solved it.
This is a bug filed here.

I specified the mount point like "sata/160GB", expecting it to mount the device in "/media/sata/160GB". But the problem started here. The system expects only a word here with no slashes(/) in it. While mounting it just creates a folder which you provided, in /media and mounts the volume there.

And this is what I did:

Open gconf-editor in terminal:
$ gconf-editor
In the left panel:
Goto:

System -> Storage -> volumes

Here you will see the mount point you specified for the device.
Change it to just a single word (OR just remove it :) )
Thats it. Replug your device.

Enjoy!!!

EDIT:
1. Do not use sudo for this purpose.
See this comment by Anonym... (Thanx to Anonym) for detail.

2. Sometimes instead of System -> Storage -> volumes you may also get System -> Storage -> drives , depending upon what you messed up. The rest process is same.

writing-udev-rules, the other way

2008-07-13T03:56:00.000-07:00

Here's my earlier post on about writing the udev rules:
writing-udev-rules, the easier way
This will give you a bit of understanding about what a udev-rule is and how can you write a udev rule on the basis of vender-id and product-id.

Here is the other way (Its easier but a bit time consuming):
So here you go..
Insert your usb-device, and watch the log:

# tail -f /var/log/messages

Jul 13 16:47:20 workbench kernel: [ 5418.740803] sd 7:0:0:0: [sdb] 312581808 512-byte hardware sectors (160042 MB)
Jul 13 16:47:20 workbench kernel: [ 5418.743055] sd 7:0:0:0: [sdb] Write Protect is off
Jul 13 16:47:21 workbench kernel: [ 5418.743072] sdb: sdb1
Jul 13 16:47:21 workbench kernel: [ 5419.323103] sd 7:0:0:0: [sdb] Attached SCSI disk
Jul 13 16:47:21 workbench kernel: [ 5419.323163] sd 7:0:0:0: Attached scsi generic sg2 type 0

Notice the third-last line. It shows that the device is mounted as sdb1.
Now lets dig into it.

# udevinfo -q path -n /dev/sdb1

/block/sdb/sdb1

This shows the devpath of the device.
From this devpath you can see a lot of information.


# udevinfo -a -p /block/sdb/sdb1

At the very first line of the output you will see:

"Udevinfo starts with the device specified by the devpath and then
walks up the chain of parent devices. It prints for every device
found, all possible attributes in the udev rules key format.
A rule to match, can be composed by the attributes of the device
and the attributes from one single parent device."

This pretty much explains itself.

And the (trimmed-)output is:

looking at device '/block/sdb/sdb1':
KERNEL=="sdb1"
SUBSYSTEM=="block"
DRIVER==""
ATTR{dev}=="8:17"
ATTR{start}=="63"
ATTR{size}=="312576642"
ATTR{stat}==" 11011 11620 0 0"

looking at parent device '/block/sdb':
KERNELS=="sdb"
SUBSYSTEMS=="block"
DRIVERS==""
ATTRS{dev}=="8:16"
ATTRS{range}=="16"
ATTRS{removable}=="0"
ATTRS{size}=="312581808"
ATTRS{stat}==" 206 10881 12228 1688 0 0 0 0 0 1272 1688"
ATTRS{capability}=="12"

...

looking at parent device '/devices/pci0000:00/0000:00:1d.7':
KERNELS=="0000:00:1d.7"
SUBSYSTEMS=="pci"
DRIVERS=="ehci_hcd"
ATTRS{vendor}=="0x8086"
ATTRS{device}=="0x24dd"
ATTRS{subsystem_vendor}=="0x8086"
ATTRS{subsystem_device}=="0x4246"
ATTRS{class}=="0x0c0320"
ATTRS{irq}=="19"
ATTRS{local_cpus}=="ff"
ATTRS{modalias}=="pci:v00008086d000024DDsv00008086sd00004246bc0Csc03i20"
ATTRS{broken_parity_status}=="0"
ATTRS{msi_bus}==""

looking at parent device '/devices/pci0000:00':
KERNELS=="pci0000:00"
SUBSYSTEMS==""
DRIVERS==""

So you can choose any block and write the rule for that.
Let me zoom into a block

looking at device '/block/sdb/sdb1':
KERNEL=="sdb1"
SUBSYSTEM=="block"
DRIVER==""
ATTR{dev}=="8:17"
ATTR{start}=="63"
ATTR{size}=="312576642"
ATTR{stat}==" 11011 11620 0 0"

So here's the rule for this :
KERNEL=="sdb1", SUBSYSTEM=="block", ATTR{dev}=="8:17", ATTR{start}=="63", ATTR{size}=="312576642", SYMLINK+="myDisk"

Now, this is also not the only rule. Go on! Generate your own rule. Mind with the spaces like in case of ATTR{stat}==" 11011 11620 0 0".

Finally place the rule in /etc/udev/rules.d/60-persistent-storage.rules. Then Plug out the device and again plug-in to see the change.


# ls /dev/ | grep my

myDisk

That's it.
If you want to learn more about it:
http://reactivated.net/writing_udev_rules.html
http://ubuntuforums.org/showthread.php?t=168221

Writing udev-rules, the easier way

2008-07-13T03:16:00.000-07:00

What is udev-rules?
udev is the device manager for the Linux 2.6 kernel series. Its primary function is managing device nodes in /dev. It is the successor of devfs and hotplug, which means that it handles the /dev directory and all user space actions when adding/removing devices, including firmware load.

Okay, here i will show you howto write udev-rule for a USB hardisk.


# lsusb 

Bus 005 Device 003: ID 04fc:0c25 Sunplus Technology Co., Ltd 
Bus 005 Device 001: ID 0000:0000  
Bus 004 Device 001: ID 0000:0000  
Bus 003 Device 001: ID 0000:0000  
Bus 002 Device 001: ID 0000:0000  
Bus 001 Device 004: ID 062a:0000 Creative Labs Optical Mouse
Bus 001 Device 001: ID 0000:0000

This gives us two information, one of them is what we want.
Very first line shows that I have a Device with vernder id: 04fc and product id:0c25 named "Sunplus Technology Co., Ltd "

The second-last line points my USB-mouse, which is not of much interest now.

Now move to the /etc/udev/rules.d directory


# cd /etc/udev/rules.d

As the device is a storage device we will be writing the rule in "60-persistent-storage.rules"
So open this file with your prefered editor (I recommend scite in gui and vim in console) and add the following line:
KERNEL=="sd*[0-9]",SYSFS{idVendor}=="04fc",SYSFS{idProduct}=="0c25", SYMLINK+="sata"

This informs udev-manager, that if any storage device with vendour-id, 04fc and product-id 0c25 is plugged into the system add a symlink in /dev with name, sata.

Note: This rule is specific to the device only. And also this is not the only rule that you can write.

This is the easiest way. And there is another way round to work on this: >Here<

Generate your gpg-key

2008-07-11T11:43:00.000-07:00

GNU Privacy Guard (GnuPG or GPG) is a replacement for the PGP suite of cryptographic software. It is freely available and is a part of Free Software Foundation's GNU software project.

Generating your gpg-key in linux
Terminal,:) the following:


~$ gpg --gen-key

You will be asked with the following options:

(1) DSA and Elgamal (default)
(2) DSA (sign only)
(5) RSA (sign only)

*nux-platform developers are crazy... there is no any reason for sth like this 1, 2 and then suddenly 5 ;)

Choose the option according to your choice if you dont know what DSA and RSA are. Just gooooogle them. I recommend choosing (2) as it gives better security. Remember it's just for signing purpose.

DSA keypair will have 1024 bits.
Please specify how long the key should be valid.
0 = key does not expire
= key expires in n days
w = key expires in n weeks
m = key expires in n months
y = key expires in n years

Choose 0 if you dont want it to expire.
Provide your Real name ( at least 5 chars ), Email address and Comment.

Conform (enter alpha-O) it and wait few secs and your key is ready.

Ps: You may be asked to move your mouse or do any thing on your desktop to refill the pool of random numbers.

I helped mozilla to make record.

2008-06-18T09:49:00.000-07:00

I helped mozilla to make the record of more than 8M (and counting) download in a day.
Here's my certificate.

where is yours?

Removing the login message.

2008-06-05T17:16:00.000-07:00

I dont know about you, but i dont like the message like "... you have new message ...." that is shown after logging in.
If you are like me and want to remove the message. Follow the following procedure. Its pretty simple:

Just create a file named ".hushlogin" in the home directory of the current user.
$ touch .hushlogin

If you want to hide this message for each new user that is created you can create the file named ".hushlogin" in /etc/skel directory.

# touch /etc/skel/.hushlogin

Remember you need root access in the second case.

UserAgent switcher in Mozilla

2008-04-16T10:48:00.000-07:00

Here's a user-agent switcher for mozilla:

http://chrispederick.com/work/user-agent-switcher/

I hope it will be of great use.

Happy Hacking!

EDIT:
I got a video tutorial for it too. Find it here.

Change ssh Welcome Banner

2008-03-18T11:56:00.000-07:00

/etc/motd

Everything you write in this file is shown as welcome banner when someone enters your into your box via ssh.

So sudo gedit /etc/motd :) enjoy!!!

Reinstall Ubuntu Grub Bootloader After Windows Wipes it Out

2008-03-18T11:53:00.000-07:00

Here's the quick and easy way to re-enable Grub.

1) Boot off the LiveCD

2) Open a Terminal and type in the following commands, noting that the first command will put you into the grub "prompt", and the next 3 commands will be executed there. Also note that hd0,0 implies the first hard drive and the first partition on that drive, which is where you probably installed grub to during installation. If not, then adjust accordingly.

$ sudo grub
> find /boot/grub/stage1

> root <the output of above command>
 > setup (hd0)
 > quit

Reboot (removing the livecd), and your boot menu should be back.

Multiple X-clients in Linux

2007-12-29T10:36:00.000-08:00

Before starting note that this is tested in ubuntu (a debian-based distro).

Here i will be assuming that you are familiar with X-system in linux.

Perhaps you know, what you will get when you press F1 to F8 with control and alt key. Well, if you don't know let me just brief it for you. By default, there are six virtual terminals in linux, F1 through F6.By pressing <ctrl> + <shift> + Fx you can switch to corresponding terminal. Next in F7 there is you your desktop manager. If you are reading this from linux, I must say this is where you currently are. In F8 you will see system logs. From F9 - F12 ...? Yes, this is where we will run other instance of desktop manager.

A brief intro about X-system:
In x-system there are two main parts X-server and X-clients. X-server simply communicates your hardware with the x-clients and a desktop manager gives a gui-environment to make the communication between the user and the x-client easier.
For detail goto wiki-page

Okay, Lets kick off:
It's just a single command. Open a terminal and login using any user-account and just enter the following command:

~$ startx -- :1 &

This command starts a new desktop-manager in screen:1 and the '&' symbol simply backgrounds the process.

The desktop manager on which you currently are, is Screen:0 ==> F7 and by issuing :1 as argument you are requesting to start it on Screen:1 ==> F9 (as you know in F8 there is system log)
Note: You might get it in F8 too or even other in other ditros.

Similarly you can start other three x-client from F10-F12 simply by choosing a from screen 2-4. By starting the x-client as user 'xyz' you will be logged in as same user. And remember you cannot start multiple x-clients in same screen.
In some distro you may also get some error or warning if you try to run it as root.

Note: I have tested it in Ubuntu. If you have tested it successfully in other distro then please post it as a comment.

Shortcuts in Terminal (console)

2007-12-07T11:03:00.000-08:00

Must of use face the problem with cutting and pasting in terminal... I know it because i did felt it a few days back too.
I don't know how but it was my luck that that i pressed ctrl+l insted of shift+l. I got amazed when i saw it cleared my console .. OMG it was a short to clear the terminal screen...

Soon after that i tested with each combination and here are the shortcuts that i found working...

ctrl+L = clear the screen
ctrl+W = clear the current word
ctrl+K = clears everything after the current curser position
ctrl+T = swaps last two letters
ctrl+U = cut
ctrl+Y = paste
ctrl+I = autocomplete (similar to pressing tab-key)
ctrl+P = Previous command (similar to pressing up-arrow)
ctrl+A = Move the cursor to the begenning
ctrl+D = same as what DEL-key does
ctrl+H = same as what BACKSPACE-Key does

...

please comment if you have any more...

Getting Relational(Designer) view in Phpmyadmin

2007-11-30T08:17:00.000-08:00

Its just simple....
just go to the phpmyadmin folder
In my case i am using lampp and and the path to phpmyadmin is:
/opt/lampp/phpmyadmin

open the file:
confing.inc.php
Note: You should be root (or use sudo command) to open the file.

Find the line:
$cfg['Servers'][$i]['pmadb'] = '';
Edit it to:
$cfg['Servers'][$i]['pmadb'] = 'phpmyadmin';
and save the file.
And also conform the the following lines exists and exactly same as below:
$cfg['Servers'][$i]['bookmarktable'] = 'pma_bookmark';
$cfg['Servers'][$i]['relation'] = 'pma_relation';
$cfg['Servers'][$i]['table_info'] = 'pma_table_info';
$cfg['Servers'][$i]['table_coords'] = 'pma_table_coords';
$cfg['Servers'][$i]['pdf_pages'] = 'pma_pdf_pages';
$cfg['Servers'][$i]['column_info'] = 'pma_column_info';
$cfg['Servers'][$i]['history'] = 'pma_history';
$cfg['Servers'][$i]['designer_coords'] = 'pma_designer_coords';

Reopen phpmyadmin and you will get, what you are searching for.

Limiting the power of Sudoers

2007-11-29T08:40:00.000-08:00

Basically in linux, a default user "root" have full access to any kind of file (every thing is file in linux, yes! even device!!!). Sometimes it is necessary for other users in the same system to access some file which are inaccessible for him by default. Command "sudo" helps to solve this problem. It is used as follows:

$sudo <command-inacessable_by_default arguments_if_any>

This Sudo command limits the user's power on the basis of the configuration made on the file "/etc/sudoers".
Generally in default case you might see something like this:
root ALL=(ALL) ALL
Above, you can see ALL 3 times. But what does it mean?
The first ALL: Run from any(all) host
The Second ALL: From any Terminal
The third ALL: Can Run any command

So, the line means the "root" run any command from any terminal from any host.
Now, how to change this? Dont ever attempt to change the power of root :) any thing may happen to your system. I cannot predict what will happen, but it is not obviously going to be good.

Yes, but you can add another user to sudoers list and limit his authority(power).Lets kick off:

Let me add another user "foo" which can have full acess to "ifconfig" command from current host.

foo HOST=(ALL) COMMAND

what do you think? will it work. Obviously not.

What does HOST and COMMAND mean?
HOST is just an alias to host(s), which i defined here.
Similarly COMMAND is a alias to command(s)

We should also define these aliases in the same file (etc/sudoers)

Host_Alias HOST = 127.0.0.1
Cmnd_Alias COMMAND =/sbin/ifconfig

If you want to give "foo" to access other commands too. you can simply append the line line with a seperator comma(,). ie:
Cmnd_Alias COMMAND =/sbin/ifconfig, <path to other command(1)>,<path to other command(2)>...

In similar fashion you can also add add other hosts too.
Further there are other 2 more types of aliases you can define:
User_Alias
Runas_Alias

I hope you got it...

you can find a detailed info by running the following line in console:
man sudoers

A visual defination of sudo:
http://howtoxyz.blogspot.com/2007/11/this-is-what-sudo-is.html :)

ref: http://www.go2linux.org/sudoers-how-to

Tux in Text

2007-11-28T12:38:00.000-08:00

Have you ever seen Text-Art of linux?
In either case you must visit this site, http://www.100mb.nl . This site contains a text picture of the Penguin (the icon of linux).
Great Art. I cannot stop myself to appreciate it.

If I am not mistaken,the text is the code of linux kernel (Obviously... not complete)

Visit it @ http://www.100mb.nl

check your download speed online...

2007-11-26T13:33:00.000-08:00

To check your download speed just click here

This site checks your download speed and even gives your ip. It also shows your download speed in graph, comparing with standard connection types.
http://www.whatismyip.com.np/checkdownlink

Its also provides you to browse anonymously from http://www.whatismyip.com.np/tools/proxy

EDIT: This isnt working anymore.

This is what sudo is.

2007-11-25T11:54:00.000-08:00

Configuring Netbeans to new look and feel

2007-11-25T11:11:00.000-08:00

Everybody wants to be unique. Isn't it...
I too want. I changed the default look and feel of the netbeans.

Adding theme

<path to netbeans>/netbeans -cp:p ${substance}\substance.jar
-laf org.jvnet.substance.SubstanceLookAndFeel

Adding Watermark

"<path to netbeans>/netbeans" -J-Dsubstancelaf.watermark = org.jvnet.substance.watermark.SubstanceKatakanaWatermark

Changing buttons laf
"<path to netbeans>/netbeans"
-J-Dsubstancelaf.gradientPainter=org.jvnet.substance.painter.WaveGradientPainter

Note: I am using the substance look and feel. You can download it from https://substance.dev.java.net/servlets/ProjectDocumentList

And finally here is what i am using recently,

/opt/netbeans-5.5/bin/netbeans" -cp:p /opt/mymodules/substance/lib/substance.jar -laf org.jvnet.substance.SubstanceLookAndFeel -J -Dsubstancelaf.watermark = org.jvnet.substance.watermark.SubstanceBinaryWatermark

Yea I have my netbeans in /opt folder and i run linux in my system.

With similar options you can also change java's default laf.

for more detail info:laf@netbeans

Opening file as root with just few clicks...

2007-11-25T10:49:00.000-08:00

[I tested it in ubuntu]
For basic user, I hope need not to go to terminal for any of of the region beside editing a file as root. You might feel bored about this. Here's a handy shortcut... ( yea, you wont need to go to terminal each time.)

First goto to the following directory create a file.
/home/<current_user>/.gnome2/nautilus-scripts

create a file with name "Open as root"
and copy and paste all this code into the file:
for a in $NAUTILUS_SCRIPT_SELECTED_URIS; do
gksudo "gnome-open $a" &
done

and save that.

and its done...

Right click on any file/ folder while browsing from "nautilus" and goto the Scripts menu and select "Open as root" .... give your password to open it.

Note: You should be in sudo-ers list to accomplish this.

!0 mins email

2007-11-19T10:22:00.000-08:00

yea an email-address for only 10 mins. Is this of any use. yea, let me explain.
Have you ever registered for any site, that require an email address for just verification purpose. Obviously it will verify you, but beside this you end up getting spam-email in your inbox too. For this case you can use the e-mail address given by http://10minutemail.com. You can check the mail received and reply too. If required you can even extend the lifetime of the email for 10 more mins.

Get a 10-min email-address at: http://10minutemail.com

batch resizing images in linux

2007-10-28T10:16:00.000-07:00

we often need to decrease the image size before uploading. You must be using some graphical software to resize them. Its not that tedious if its one or two but what if you have to resize a large numbers of images!!!. This is what i do.

Basically two commands are used here.
1. djpeg - decompress a JPEG file to an image file
2. cjpeg - compress an image file to a JPEG file

So to resize, i run this script on a folder containing the image files.

#!/bin/sh

mkdir resized
for i in *.JPG
do
echo 'Resizing image..' $i
djpeg -scale 1/2 $i | cjpeg > resized/$i
done

After script is done, a folder named 'resized' is created containing the resized images.

Note:
Both djpeg and cjpeg aren't installed by default, they're part of libjpeg-progs package. Under Ubuntu you can get it by

sudo apt-get install libjpeg-progs

(source: jwalanta.blogspot.com)

switch from xp to linux,

2007-09-29T13:14:00.000-07:00

I know its was not easy for me to switch from xp to linux(ubuntu). The first thing that made me difficult was that there was not any type of media-player that could play my mp3-library. Though there was totem movie player it didnt played my library due to missing codec.
The next first thing that made me difficult to use linux was the name given to applications. Most of them were irrelevant for me. Lets take "amarok", it didnt have any significant meaning (at least not for me). I heard its name from my friend and got to know that it was audio-player.
There were so many of other problems i faced that include burining a disk,installing from tar.gz or tar.bz2 by making own compilation, or using internet, etc

Though i found it a bit later after i switched to linux. This link was very helpful for me.

The Linux alternative project

Edit:
One More:
http://www.webi.org/osalternative.html

real-time traffic data on your blog/site

2007-09-27T12:07:00.000-07:00

You might be wondering, is there any service provider that serves real-time traffic data in your site. The answer is yes,
And here is the solution

http://feedjit.com/

you can also see it aside in this blog.

How to Download From YouTube?

2007-09-13T08:25:00.000-07:00

Just copy the link location of your video from you tube.

And Open any of the following site and Enter your link to youTube Video there.

http://video.qooqle.jp/dl/
http://www.kissyoutube.com

You can also use extension for mozilla internet explorer. You can get the extension here;
http://javimoya.com/blog/youtube_en.php

How to hide your file?

2007-08-12T11:08:00.000-07:00

This howto is for Microsoft OS'es only.
1.Gather your image and the files you wish to lodge into it. Here I have a meeting.txt which which I will slap inside my secret.jpg

2.Add the files you want to hide into a new RAR archive
Open Command Prompt

3.Go to the folder where your files are located, in this case 'C:\hidden'
Type 'copy /b secret.jpg + meeting.txt.rar lizard.jpg' where secret.jpg is the original picture, meeting.txt.rar is the file to be hidden, and lizard.jpg is the file which contains both.

4.Test the JPG by opening it, and verifying it still opens. If it does, try opening the file with WinRar!

5.The completed RAR file!

The link to the original page:
http://www.thetechtray.net/2007/05/30/hiding-files-in-jpegs