malayamaarutham

putty configuration

2012-01-16T00:03:00.005-05:00

My favorite putty configuration

Window -> Appearance -> Gap between text and window edge = 3
Terminal -> Features -> Disable remote-controlled window title changing -> check

keywords: stop putty from changing the title dynamically
references:
putty home page

verizon router dhcp getting a fixed IP address

2011-12-25T22:50:00.006-05:00

I am currently using Verizon DSL to connect to the internet. So, I have

laptop -> router -> internet

A minor irritation with this set up is that the router can potentially assign different IP addresses whenever I do a reboot or something akin to /etc/init.d/networking restart. For example today it can be 192.168.1.58, tomorrow it could be 192.168.1.68 etc.,

I currently have


$ifconfig                                                                                                                             
eth0      Link encap:Ethernet  HWaddr 00:15:c5:19:9c:1a  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:17 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:6790 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6790 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:773105 (754.9 KiB)  TX bytes:773105 (754.9 KiB)

wlan0     Link encap:Ethernet  HWaddr 00:13:02:9e:cc:1b  
          inet addr:192.168.1.21  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::213:2ff:fe9e:cc1b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:7486622 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4833561 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2650697959 (2.4 GiB)  TX bytes:608573891 (580.3 MiB)

To have the same IP address, say 192.168.1.78, every time the computer is booted

1) Add the following lines to /etc/dhcp/dhclient.conf


alias {
  interface "wlan0";
  fixed-address 192.168.1.78;
  option subnet-mask 255.255.255.255;
}

2) restart the network


sudo /etc/init.d/networking restart

Now you should see


$ifconfig                                                                                                                             
eth0      Link encap:Ethernet  HWaddr 00:15:c5:19:9c:1a  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:17 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:6790 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6790 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:773105 (754.9 KiB)  TX bytes:773105 (754.9 KiB)

wlan0     Link encap:Ethernet  HWaddr 00:13:02:9e:cc:1b  
          inet addr:192.168.1.21  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::213:2ff:fe9e:cc1b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:7486678 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4833604 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2650705479 (2.4 GiB)  TX bytes:608589238 (580.3 MiB)

wlan0:0   Link encap:Ethernet  HWaddr 00:13:02:9e:cc:1b  
          inet addr:192.168.1.78  Bcast:0.0.0.0  Mask:255.255.255.255
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

Note the new wlan:0 interface which is always assigned to 192.168.1.78.

extract historical versions of a file tracked by git

2011-08-07T14:05:00.004-04:00

Say, I have a file test.txt being tracked by git.

$git log test.txt
commit 809ebdbd3c44b9310a7a0f67d61897d5d8f9b6d2
Author: rajulocal 
Date:   Sun Aug 7 14:11:31 2011 -0400

    version 15

commit aec45562ad09257ce85eaf00f5a4fa6912e9e51e
Author: rajulocal 
Date:   Sun Aug 7 14:11:21 2011 -0400

    version 14

commit 7fb63da179a2026ba92a8875ff7d3da881ef5854
Author: rajulocal 
Date:   Sun Aug 7 14:11:11 2011 -0400

    version 13

commit 9b3ca5d3d7497e44c012f5ccd5daced2dd90ec12
Author: rajulocal 
Date:   Sun Aug 7 14:10:51 2011 -0400

    version 12

commit d0b5471fa2abce0057cce1d61240e78c09406c04
Author: rajulocal 
Date:   Sun Aug 7 14:10:40 2011 -0400

    version 11

commit e3af4e1a85b4ff07c31c8dcda47eb41c3f3c830b
Author: rajulocal 
Date:   Sun Aug 7 14:10:26 2011 -0400

    version 10

commit be762c0ee45ec6046fa960cace9acae513b80137
Author: rajulocal 
Date:   Sun Aug 7 14:10:18 2011 -0400

    version 9

commit 03ad798434559300cff26f6a238d7b0f05ad53d2
Author: rajulocal 
Date:   Sun Aug 7 14:09:59 2011 -0400

    version 8

commit 94c50cce3b24e572133eeaedc5bfe00aad568aec
Author: rajulocal 
Date:   Sun Aug 7 14:09:52 2011 -0400

    version 7

commit ab63e2bc7b258f702cc8c516c1f16bafc754cf27
Author: rajulocal 
Date:   Sun Aug 7 14:09:44 2011 -0400

    version 6

commit 16c896d19e00267b63537596485074488cd20a85
Author: rajulocal 
Date:   Sun Aug 7 14:09:37 2011 -0400

    version 5

commit 6937331a12209121ba24d111e1ca5128a3c1e836
Author: rajulocal 
Date:   Sun Aug 7 14:09:21 2011 -0400

    version 4

commit 7ec1c7f98a152f6b760ff1561a3b805cc5e374e9
Author: rajulocal 
Date:   Sun Aug 7 14:09:13 2011 -0400

    version 3

commit 5b3788ad1bdef15c1895a6efefcdd1ea96c840e9
Author: rajulocal 
Date:   Sun Aug 7 14:09:01 2011 -0400

    version 2

commit 1306cba057d6cac06ffd39b9234ce72967dc44f8
Author: rajulocal 
Date:   Sun Aug 7 14:08:35 2011 -0400

    version 1

In order to extract the latest 12 versions of test.txt and store each into a different file, I do

$xtract_hist_git 12 test.txt
$ls m??_test.txt            
m00_test.txt  m02_test.txt  m04_test.txt  m06_test.txt  m08_test.txt  m10_test.txt  m12_test.txt
m01_test.txt  m03_test.txt  m05_test.txt  m07_test.txt  m09_test.txt  m11_test.txt

m00_test.txt is the latest copy of test.txt, m01_test.txt is the latest but one copy, m02_test.txt is the latest but two copy etc.,

xtract_hist_git is this little script

$cat ~/bin/xtract_hist_git           
#! /bin/sh
#
# Author               : Kamaraju S. Kusumanchi
# Email                : kamaraju at gmail dot com
# File                 : ~/bin/xtract_hist_git
# Date (last modified) : Sun Aug  7 14:28:14 EDT 2011

revs=$1
file=$2

for i in `seq -w 0 $revs`
do
  git checkout master~$i $file
  mv $file m${i}_$file
done
git checkout master $file

get all the odd lines in a file

2011-06-14T08:51:00.004-04:00

sed can be used to get all the odd or even lines in a file. Consider, for example,


$cat linenums.txt
 line 1
 line 2
 line 3
 line 4
 line 5
 line 6
 line 7
 line 8
 line 9
 line 10

To print all the odd lines


$sed -n '1~2p' linenums.txt 
 line 1
 line 3
 line 5
 line 7
 line 9


$sed -n '2~2p' linenums.txt
 line 2
 line 4
 line 6
 line 8
 line 10

login into a directory after sshing into a machine

2011-02-26T13:34:00.003-05:00

To login into a machine via ssh and cd into a particular directory immediately afterwards, use

ssh -t user@machine.name 'cd ~/destination/directory && exec /bin/bash --login -i'

The -t option forces the ssh to open a pseudo-terminal. Without the -t option, ssh does not open the pseudo-terminal when a command is specified.

Commands can also contain variable names. For example,

export DYNAMIC=${PWD#$HOME/}
ssh -t user@machine.name "cd ~/$DYNAMIC && exec bash --login -i"

Other possible uses of the -t option

To see the output of top of a remote machine, use

ssh -t user@remote.machine.name top

Add a number to a variable in shell script

2011-02-02T01:01:00.012-05:00

Consider the following shell script

$cat add_variables_02.sh
#! /bin/sh
ov=10;
nv=$((ov+3));      echo $nv
((nv=ov+3));       echo $nv
nv=$ov+3;          echo $nv
nv=`expr $ov+3`;   echo $nv
nv=`expr $ov + 3`; echo $nv

Execute in a shell

$bash add_variables_02.sh 
13
13
10+3
10+3
13

The first two methods nv=$((ov+3)) or ((nv=ov+3)) are faster than the fifth method nv=`expr $ov + 3` as the former uses bash's own feature and the later runs an external command in a subprocess.

Also, note that spaces are needed before and after the '+' character when expr is used.

Tested in Debian Wheezy machine using bash 4.2-1

Further reading

info coreutils 'expr invocation'
man expr

Special thanks to the anon 2011-08-24 5:06 AM for providing the first two methods.

recover an accidentally overwritten partition table

2010-08-21T02:30:00.016-04:00

shorter version:

Q. I accidentally overwrote the partition table on my computer. Now it does not boot. Is there any way to restore it back?
A. use the testdisk program. Debian users can install it by doing

# apt-get install testdisk

To run it, use the command

# testdisk

This tool is very powerful, easy to use and interactive. It can be run from a live CD. I used it to recover the ext3, Linux swap partition information.

Long story:

My favorite tool for partitioning is qtparted. I got hooked to it couple of years back when I was trying out a knoppix live CD.

The hard drive of my laptop is /dev/sda. I recently bought a 500 GB external USB hard drive. When I connected the USB hard drive, it was recognized as /dev/sdb. I used the qtparted program to partition the /dev/sdb.

The partitioning process went smoothly. But when I click on the /dev/sdb link in the left tab of qtparted window, there were error messages on my konsole


$sudo qtparted
No Implementation: Support for opening ntfs file systems is not implemented yet.
Error: File system has an incompatible feature enabled.  Compatible features are has_journal, dir_index, filetype, sparse_super and large_file.  Use tune2fs or debugfs to remove features.
Error: File system has an incompatible feature enabled.  Compatible features are has_journal, dir_index, filetype, sparse_super and large_file.  Use tune2fs or debugfs to remove features.

Not sure of what it means, I resorted to cfdisk (a Curses based tool for partitioning).

My intention was to delete all the partitions on /dev/sdb and start afresh. However, I ended up deleting all the ext3, swap partitions on /dev/sda by accident. Notice how cfdisk only lists /dev/sda and nothing about /dev/sdb?

When the changes are committed, it gave an error. It asked me to reboot the machine in order to fix the error.

When the laptop is rebooted, Grub does not load. IIRC, the error code was 17. My computer is now officially in a half baked state with the wrong partition table (all because of my stupidity).

Kumar Appiah suggested me to try testdisk. He used it before to recover some FAT32, NTFS partitions.

So, I popped in an old Ubuntu (hoary) live CD to see if it has testdisk. It does not. The Hoary was released a while back. The official repositories were removed. So a simple

# sudo apt-get update

did not work. I modifed the /etc/apt/sources.list to point to dapper instead of hoary. Then did an apt-get update, apt-get install testdisk.

In order to install testdisk from dapper onto hoary, apt-get wanted to install a new kernal and remove the current kernel. I let the upgrade process run and gave it a 'no' when it wanted to remove the current kernel during the post configure stage. This exited the apt-get process abruptly.

Then, I did a "sudo apt-get -f install" to fix the inconsistent state. I then had to do another "sudo apt-get install testdisk". This time it proceeded without any difficulty.

Once testdisk is installed in the RAM, running it was easy. Just execute

# testdisk

The instructions in testdisk screens are very clear. At the end, I was able to recover my original partition table. Kudos to the authors, Debian maintainers of testdisk and to Kumar for suggesting it.

Useful links:
. websites of testdisk , qtparted
. links to debian packages testdisk, qtparted, e2fsprogs

options in function variables octave

2010-06-15T06:46:00.004-04:00

The following octave code shows how to make functions take different paths depending on a user specified choice. It is a little template that comes in handy once in a while.

$cat options_in_function_variables_01.m
# Author : Kamaraju S. Kusumanchi
# Email  : kamaraju at gmail dot com
# Last modified : Tue Jun 15 06:45:15 EDT 2010
function [X] = options_in_function_variables_01(X, choice)

if (strcmp(choice, "square"))
 X = X*X;
elseif (strcmp(choice, "unity"))
 X = X*1;
elseif (strcmp(choice, "cube"))
 X = X*X*X;
else
 printf("choice = %s is not a valid option.\n", choice);
 error("please provide a correct choice");
endif
endfunction

To test it


$octave -qf
octave:1> options_in_function_variables_01(2.2, 'unity')
ans =  2.2000
octave:2> options_in_function_variables_01(2.2, 'square')
ans =  4.8400
octave:3> options_in_function_variables_01(2.2, 'cube')
ans =  10.648
octave:4> 10.648/4.84
ans =  2.2000
octave:5> 4.84/2.2
ans =  2.2000

passing functions as arguments in octave

2010-05-17T00:08:00.002-04:00

It is possible to pass functions as arguments to another function in Octave. Consider the following sample code


$ls
cube.m  dynamic.m  script.m  square.m

$cat square.m
function [sq] = square(x)
sq = x**2;
endfunction

$cat cube.m
function [cu] = cube(x)
cu = x**3;
endfunction

$cat dynamic.m
function [ ret ] = dynamic (fh, x)
# fh is a function name passed as a string
# ex:-    b = dynamic("cube", a);
# fh can also be a handle
#         handle = @square;
#         b = dynamic(handle, a);
ret = feval(fh, x);
endfunction

$cat script.m
a=5.0

# bh = b obtained by using handle as arguments
handle=@square;
bh = dynamic( handle, a)

# bs = b obtained by using strings as arguments
bs = dynamic("square", a)

# ch = c obtained by using handle as arguments
handle=@cube;
ch = dynamic( handle, a)

# cs = c obtained by using strings as arguments
cs = dynamic("cube", a)

Run the script.m in octave


$octave3.2 -qf script.m

a =  5
bh =  25
bs =  25
ch =  125
cs =  125

Tested using Debian Lenny (stable), Octave 3.2.4

Further Reading:
1) The section on "Function handles, Inline Functions, and Anonymous Functions" in the octave manual http://www.gnu.org/software/octave/doc/interpreter/Function-Handles-Inline-Functions-and-Anonymous-Functions.html

2) http://rosettacode.org/wiki/Higher-order_functions explains how to do this kind of "calling functions from functions" in various programming languages

load data file with header lines in octave

2010-04-25T18:51:00.004-04:00

When a data file contains some header lines before the actual data matrix, octave's dlmread function can be used to read the matrix of data and ignore the headers.

For example,

$cat input_data.m
col1 col2 col3
1, 2, 3
4, 5, 6
7, 8, 9
10, 11, 12

This file contains one header line and a 4x3 data matrix. To read it into octave, create a script called

$cat read_data.m
1;
A = dlmread("input_data.m", SEP=',', R0=1, C0=0);
A

$octave3.2 -qf
octave3.2:1> read_data
A =

1 2 3
4 5 6
7 8 9
10 11 12

For more information on dlmread function, use 'help dlmread' inside octave.

Tested using octave 3.2.4-3 on Debian stable (Lenny).

print a file by line numbers

2009-09-09T13:50:00.007-04:00

Consider the file

$ cat name.txt
1 k
2 ka
3 kam
4 kama
5 kamar
6 kamara
7 kamaraj
8 kamaraju
9 kamaraju
10 kamaraju k
11 kamaraju ku
12 kamaraju kus
13 kamaraju kusu
14 kamaraju kusum
15 kamaraju kusuma
16 kamaraju kusuman
17 kamaraju kusumanc
18 kamaraju kusumanch
19 kamaraju kusumanchi

To print the contents of lines between 5 and 8

$ sed -n '5,8p' name.txt
5 kamar
6 kamara
7 kamaraj
8 kamaraju

$echo $?
0

To print the lines 10 to 20, just do

$ sed -n '10,20p' name.txt
10 kamaraju k
11 kamaraju ku
12 kamaraju kus
13 kamaraju kusu
14 kamaraju kusum
15 kamaraju kusuma
16 kamaraju kusuman
17 kamaraju kusumanc
18 kamaraju kusumanch
19 kamaraju kusumanchi

$echo $?
0

Note that this command is successful even though the specified right limit (20) is greater than the number of lines in the file (19).

To print the nth line of a file (w.l.g. say n=8), just do

$ sed -n 8p name.txt
8 kamaraju

$ echo $?
0

End of line is represented by $. So, to print from 17th line till the end of the file, do

$ sed -n '17,$p' name.txt
17 kamaraju kusumanc
18 kamaraju kusumanch
19 kamaraju kusumanchi

$ echo $?
0

No theme index file.dpkg error

2009-06-20T00:02:00.003-04:00

While trying to upgrade to texmacs 1:1.0.7.2-1in Sid (unstable) on a machine running Debian Lenny (Stable), I was getting the following error

$sudo apt-get install texmacs
// bunch of apt-get messages

Setting up texmacs-common (1:1.0.7.2-1) ...
gtk-update-icon-cache: No theme index file.dpkg: error processing texmacs-common (--configure):
subprocess post-installation script returned error exit status 1
dpkg: dependency problems prevent configuration of texmacs:
texmacs depends on texmacs-common (= 1:1.0.7.2-1); however:
Package texmacs-common is not configured yet.
dpkg: error processing texmacs (--configure):
dependency problems - leaving unconfigured
Errors were encountered while processing:
texmacs-common
texmacs
E: Sub-process /usr/bin/dpkg returned an error code (1)

Install the gnome-icon-theme package to solve this bug.
$sudo apt-get install -t stable gnome-icon-theme
//bunch of apt-get messages

Selecting previously deselected package gnome-icon-theme.
(Reading database ... 225097 files and directories currently installed.)
Unpacking gnome-icon-theme (from .../gnome-icon-theme_2.22.0-1_all.deb) ...
Setting up texmacs-common (1:1.0.7.2-1) ...
gtk-update-icon-cache: Cache file created successfully.
Setting up texmacs (1:1.0.7.2-1) ...
Setting up gnome-icon-theme (2.22.0-1) ...

running external commands

2009-06-04T23:35:00.008-04:00

To run external commands while editing a file in vim, use the '!' in the normal mode. For example
```
:!ls -al
```
will list the files
```
:!date
```
will display the current date.
To read the output of external commands into the current file, do
```
:r !date
```
All the commands are run in normal mode. Press ESC key to enter the normal mode in vim.

Further reading:- :help :!

To run external commands in octave, use the system command. Sample octave session looks as

$octave -q
octave:1> system("date")
Thu Jun  4 23:49:23 EDT 2009
ans = 0
octave:2> [ret_code output] = system("date");
octave:3> ret_code
ret_code = 0
octave:4> output
output = Thu Jun  4 23:49:40 EDT 2009

octave:5> exit

Further reading :- "doc system" shows the relevant help pages in octave.

To run external commands in Fortran 90 programs, use the system command. Sample code looks as below

$cat system.f90
program callsystem
       implicit none
       !to examine the behaviour of the system command
       character (len=100)::cmd
       cmd="echo Wake up Neo"
       !if u are using ifc compiler use -Vaxlib during compilation
       call system(cmd//achar(0))
       call system(cmd)
       call system("date")
       ! The next line also works.
       ! call system("ls")
end program callsystem

$gfortran system.f90

$./a.out
Wake up Neo
Wake up Neo
Thu Jun  4 23:55:07 EDT 2009

To run the external commands in C, use the system command available in stdlib.h. Sample code will be

$cat system.c
#include stdio.h
#include stdlib.h

int main() {
     /* Fixme :- <, > in the header files are not showing up on blogspot */
     int ret_code;
     ret_code = system("date");

     printf("%d\n", ret_code);
     return 0;
}

$gcc -Wall system.c

$./a.out
Fri Jun  5 00:04:14 EDT 2009
0

Further reading :- man system

All the above are tested in Debian Lenny using vim 7.1, octave 3.0.1, gfortran 4.3.1, gcc 4.3.1

file test operators in bash

2009-04-23T22:28:00.006-04:00

Often while writing shell scripts, various tests need to be performed on files. For example, we need to check if a file exists before copying it somewhere. We need to check the existence of a directory before writing files into it.

Bash comes with the following list of operators to perform these tests.

Operator    Tests Whether
-e          File exists
-f          File is a regular file
-d          File is a directory
-h          File is a symbolic link
-L          File is a symbolic link
-b          File is a block device
-c          File is a character device
-p          File is a pipe
-S          File is a socket
-t          File is associated with a terminal

-N          File was modified since last read
-O          You own the file
-G          Group id of the file is same as yours

-s          File is not zero size

-r          File has read permission
-w          File has write permission
-x          File has execute permission

-g          sgid flag set
-u          suid flag set
-k          "sticky bit" set

F1 -nt F2   File F1 is newer than F2 *
F1 -ot F2   File F1 is older than F2 *
F1 -ef F2   Files F1 and F2 are hard links to the same file *


!           NOT (inverts the sense of above tests)

* signifies a binary operator (requires two operands).

Reference :- Appendix B of "Advanced Bash-Scripting guide" by Mendel Cooper, Version 6.5. Debian users can get this document by installing the abs-guide package.

sudo apt-get install abs-guide

The necessary files can be found in /usr/share/doc/abs-guide . However, the abs-guide package contains only the html version of the document. A pdf version can be downloaded from http://www.tldp.org/LDP/abs/abs-guide.pdf .

script to get the external IP address

2009-03-30T00:10:00.003-04:00

When a machine sits behind a router, it has two IP addresses. One internal (assigned by the router), one external (assigned by the ISP). To find the external IP address of the machine, I use the following script called ip.

$cat ip
#! /bin/sh

# get the external IP address of the machine
# Author : Kamraju Kusumanchi
# Date   : Mon Mar 30 00:08:11 EDT 2009

curl www.whatismyip.org
echo ""

On my machine, I have

$curl --version
curl 7.18.2 (i486-pc-linux-gnu) libcurl/7.18.2 OpenSSL/0.9.8g zlib/1.2.3.3 libidn/0.6.5 libssh2/0.18
Protocols: tftp ftp telnet dict ldap ldaps http file https ftps scp sftp
Features: GSS-Negotiate IDN IPv6 Largefile NTLM SSL libz

Execution

$which ip
/home/rajulocal/bin/ip

$ip
141.153.242.115

IP spoofing with iceweasel

2009-02-14T00:01:00.012-05:00

This tutorial explains how to spoof the IP addresses using iceweasel (firefox) web browser on machines running Debian Linux.

Install the Iceweasel browser, tor button extension

$sudo apt-get install iceweasel iceweasel-torbutton

Install the privoxy, tor packages
```
$sudo apt-get install privoxy tor
```
Configure privoxy by adding the following line to /etc/privoxy/config
```
forward-socks4a / 127.0.0.1:9050 .
```
Note the '.' at the end. It is important.

Restart the privoxy

$sudo /etc/init.d/privoxy restart
Restarting filtering proxy server: privoxy.

Restart the tor daemon

$sudo /etc/init.d/tor restart
Stopping tor daemon: tor.
Raising maximum number of filedescriptors (ulimit -n) to 32768.
Starting tor daemon: tor...
Feb 14 00:14:49.473 [notice] Tor v0.2.0.30 (r15956). This is experimental software. Do not rely on it for strong anonymity. (Running on Linux i686)
Feb 14 00:14:49.474 [notice] Initialized libevent version 1.3e using method epoll. Good.
Feb 14 00:14:49.474 [notice] Opening Socks listener on 127.0.0.1:9050
done.

Start the iceweasel. Use ctrl+2 to enable tor. The status of the tor button is visible in the right bottom box of the iceweasel window. The screenshots below might be helpful.

Note: ctrl+2 acts as a toggle switch to enable/disable tor.
Change the proxy. Right click on the tor button (bottom right corner of iceweasel) -> choose preferences -> select "use custom proxy settings"
Click on "Test Settings" then click "ok" to test for proxy settings. If everything went successful, there will be a confirmation.
Check the new spoofed "IP address" by visiting sites such as www.whatismyip.com etc., This will be the IP address seen by the websites you visit.

Tor has its limitations. It will not give complete anonymity but something good enough for most purposes. Use at your own risk.

The above tutorial is tested in Debian Lenny, iceweasel 3.0.5, tor 0.2.0.30, privoxy 3.0.9, torbutton 1.2.0.

Back ground story :- While hopping around the internet, I came across some articles which claim to track the "identity thefters" via the IP address hits to a website. This is a good approach but we have to understand that it has its own limitations. Using this article, I just wanted to point out that it is very easy to hide one's IP address tracks. Dont be misled by the IP hits...

open a new gvim window from gvim

2008-10-25T21:18:00.004-04:00

To open a new gvim window from an existing gvim window use

:silent !gvim

If there are any errors in the original window, the screen can be refreshed by

:redraw!

or by simply pressing ctrl-l.

For more help, see :!cmd, :silent in the vim help pages.

This tip was tested in vim 7.0 on a machine running Debian Etch.

accessing wpa wireless networks

2008-03-22T17:39:00.000-04:00

This article explains accessing a wireless connection with WPA TKIP encryption using a Dell Inspiron E1505 laptop running Debian Etch. The final network connection is going to look like

ISP <---> wrt54g router <---> Dell Inspiron E1505 laptop

where ISP is the Internet Service Provider such as roadrunner, comcast etc., (and in my case "clarity connect").

The main steps involved are

configure the router
Install the necessary software packages on the Debian machine
encrypt the password (if necessary)
add a network stanza in /etc/network/interfaces
restart the network

The information about the wireless card can be found by using

sudo lspci --vv

In this case, we have

0b:00.0 Network controller: Intel Corporation PRO/Wireless 3945ABG Network Connection (rev 02)

The router is configured as shown below.

The SSID stands for "Service Set Identifier". It is basically the name of the wireless network. In this example, it is set to "Raju_and_Satish". Change the SSID according to your network.

A list of available networks and their SSIDs can be obtained by using

iwlist scan

As can be seen from snapshot 2, the router is configured to use TKIP as its WPA encryption algorithm.

The "WPA Shared Key" (snapshot 2) is the place holder for setting a password to the network. Since the password is usually a bunch of ASCII characters, it is also referred as a "passphrase". In this example, the password for the network is "strongpassword". Change it according to your network.

Install the necessary software by using the apt-get command. I have installed

firmware-ipw3945
ipw3945-modules-2.6-686
ipw3945-modules-2.6.18-6-686
ipw3945d
wpasupplicant

I am not sure if all the above packages are needed for the network configuration, but I know that they are sufficient. If anyone knows a leaner version of the necessary packages, please let me know and I will update this list.

The next step is to generate an encrypted string known as the pre-shared key (PSK) from the ASCII password and the SSID. This can be achieved using the wpa_passphrase command.

$wpa_passphrase Raju_and_Satish strongpassword
network={
   ssid="Raju_and_Satish"
   #psk="strongpassword"
   psk=604d8887badd597a8647f65b98c3c504ad29ba352211033adfed01cd8c3034a0
}

After this, add the following stanza to the /etc/network/interfaces.


# wireless setup
auto eth2
iface eth2 inet dhcp
wpa-conf managed
wpa-ssid Raju_and_Satish
wpa-key-mgmt WPA-PSK
wpa-psk 604d8887badd597a8647f65b98c3c504ad29ba352211033adfed01cd8c3034a0

Replace the wpa-ssid, wpa-psk with the values corresponding to your network configuration.

Then restart the network connections by doing

$sudo /etc/init.d/networking restart

Now the network should be up and running. Its status can be tested by using host, ping commands.


$host www.google.com
www.google.com          CNAME   www.l.google.com
www.l.google.com        A       216.239.51.104
www.l.google.com        A       216.239.51.99

$ping -c3 www.google.com
PING www.l.google.com (216.239.51.99) 56(84) bytes of data.
64 bytes from 216.239.51.99: icmp_seq=1 ttl=242 time=40.7 ms
64 bytes from 216.239.51.99: icmp_seq=2 ttl=242 time=40.9 ms
64 bytes from 216.239.51.99: icmp_seq=3 ttl=242 time=39.6 ms

--- www.l.google.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 10124ms
rtt min/avg/max/mdev = 39.616/40.437/40.985/0.635 ms

weather in ithaca

2008-02-26T18:16:00.000-05:00

To find the weather in Ithaca using a Linux box, add the following lines to the ~/.weatherrc . Use /etc/weatherrc for site-wide configuration.

$cat /home/rajulocal/.weatherrc
[default]
City = ITHACA
Forecast = True
ID = KITH
St = NY

After that you can get the current weather conditions and forecast by using the weather command.

$weather
Current conditions at Ithaca Tompkins Regional Airport (KITH)
Last updated Feb 26, 2008 - 05:56 PM EST / 2008.02.26 2256 UTC
 Wind: from the WNW (300 degrees) at 3 MPH (3 KT)
 Sky conditions: obscured
 Weather: light snow; mist
 Precipitation last hour: A trace
 Temperature: 31.1 F (-0.5 C)
 Relative Humidity: 95%
City Forecast for Ithaca, NY
Issued Tuesday afternoon - Feb 26, 2008
 Tuesday night... Low 21, 100% chance of precipitation.
 Wednesday... Snow showers, high 22, 80% chance of precipitation.
 Wednesday night... Low 9, 40% chance of precipitation.
 Thursday... Very cold, high 19.
 Thursday night... Low 9.

Weather uses METAR data that it fetches from the the National Oceanic and Atmospheric Administration and forecasts from the National Weather Service. The list of weather stations and their codes can be obtained from http://www.rap.ucar.edu/weather/surface/stations.txt .

Tested on Debian Etch using

$weather --version
weather 1.2

browse gcc source code

2007-11-22T10:24:00.000-05:00

To browse the source code of gcc use http://gcc.gnu.org/viewcvs/ . For example, to look at the contents of trunk/gcc/testsuite/gcc.c-torture/execute/ directory, just go to http://gcc.gnu.org/viewcvs/trunk/gcc/testsuite/gcc.c-torture/execute/ . Similarly, to view the contents of a particular file, say pr34130.c use http://gcc.gnu.org/viewcvs/trunk/gcc/testsuite/gcc.c-torture/execute/pr34130.c?revision=130258&view=markup

Situation:
Recently, a miscompilation bug has been discovered in gcc. It affects all the gcc versions from 3.3.6 to 4.2.2. This bug is fixed in 4.3.0 and a testcase trunk/gcc/testsuite/gcc.c-torture/execute/pr34130.c has been added to the testsuite so that the same problem does not arise in the future versions. I wanted to take a quick peek at this file but was not ready to download 1.2 gigabytes of gcc's svn repository just for this. The above tip came in handy under this scenario.

Alternate solutions:
1. If you are familiar with svn, it is possible to do

svn -q co svn://gcc.gnu.org/svn/gcc/trunk/gcc/testsuite/gcc.c-torture/execute execute

and download just the trunk/gcc/testsuite/gcc.c-torture/execute directory.

Related links :-

http://gcc.gnu.org/svn.html
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34130
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=452108

list of predefined macros

2007-10-13T10:11:00.000-04:00

Situation:

guile-1.8_1.8.2+1 failed to build on alpha architecture. The complete build log can be found at http://buildd.debian.org/fetch.cgi?&pkg=guile-1.8&ver=1.8.2%2B1-1&arch=alpha&stamp=1188086025&file=log

The buildlog tells us that the problem is in line 96 of test-round.c . To debug the problem further, the source of guile-1.8 can be downloaded by using


$cd practice/guile/
$apt-get source --download-only guile-1.8
$dpkg-source -x guile-1.8_1.8.2+1-2.dsc
$cd guile-1.8-1.8.2+1/

To see where test-round.c is residing


$find . -iname '*test-round.c*'
./test-suite/standalone/test-round.c

Now when we look at the source code of test-round.c around line 96


$cd test-suite/standalone/
$vim +96 test-round.c

we find that there is a predefined macro called DBL_MANT_DIG . But what is its value? More generally, how can we get a list of all the predefined macros and their values?

Solution:
The answer is surprisingly simple. Just do


$g++ -E -dM - < /dev/null

#define __DBL_MIN_EXP__ (-1021)
#define __FLT_MIN__ 1.17549435e-38F
#define __DEC64_DEN__ 0.000000000000001E-383DD
#define __CHAR_BIT__ 8
#define __WCHAR_MAX__ 2147483647
#define __DBL_DENORM_MIN__ 4.9406564584124654e-324
#define __FLT_EVAL_METHOD__ 2
#define __DBL_MIN_10_EXP__ (-307)
#define __FINITE_MATH_ONLY__ 0
#define __GNUC_PATCHLEVEL__ 3
#define __DEC64_MAX_EXP__ 384
#define __SHRT_MAX__ 32767
#define __LDBL_MAX__ 1.18973149535723176502e+4932L
#define __UINTMAX_TYPE__ long long unsigned int
#define __linux 1
#define __DEC32_EPSILON__ 1E-6DF
#define __unix 1
#define __LDBL_MAX_EXP__ 16384
#define __linux__ 1
...

Since our interest is in the predefined macro DBL_MANT_DIG, the above output can be filtered by using grep.


$g++ -E -dM - < /dev/null  | grep -i __DBL

#define __DBL_MIN_EXP__ (-1021)
#define __DBL_DENORM_MIN__ 4.9406564584124654e-324
#define __DBL_MIN_10_EXP__ (-307)
#define __DBL_DIG__ 15
#define __DBL_MAX__ 1.7976931348623157e+308
#define __DBL_HAS_INFINITY__ 1
#define __DBL_MAX_EXP__ 1024
#define __DBL_MIN__ 2.2250738585072014e-308
#define __DBL_HAS_QUIET_NAN__ 1
#define __DBL_HAS_DENORM__ 1
#define __DBL_MANT_DIG__ 53
#define __DBL_EPSILON__ 2.2204460492503131e-16
#define __DBL_MAX_10_EXP__ 308

This clearly tells us that DBL_MANT_DIG is 53 on this particular machine. More information about macros like DBL_MANT_DIG can be found in files

/usr/share/doc/glibc-doc-reference/html/Floating-Point-Parameters.html
/usr/share/doc/glibc-doc-reference/html/IEEE-Floating-Point.html
/usr/share/doc/glibc-doc-reference/html/Library-Summary.html

etc., which are all part of glibc-doc-reference package. On a Debian machine, this package can be installed by doing


$apt-get install glibc-doc-reference

websites incompatible with iceweasel

2007-10-01T12:44:00.001-04:00

As we all know, iceweasel is basically a renamed version of firefox in Debian. The renaming was due to licensing issues. Except for the renaming there is no difference between firefox and iceweasel.

The following are the list of websites that wont work properly with iceweasel. The tests are performed with iceweasel 2.0.0.16, Debian Etch (Stable).

http://www.nbc.com/Heroes/video/episodes/ - videos do not play even though Adobe flash player is installed.
www.citicards.com - website does not even load.
http://jpmorganfantasyfuturesusa.crowngr.com/ - page gives a runtime error

It is not very difficult to design a website which works the same way on all the browsers. I wonder why these companies are so incompetent in putting up a W3C standard complaint web site and not use any proprietary software. It also makes one wonder, if it would be better to take the business to companies who have the decency/ability to set up a browser-friendly website?

Updated on : Sep 25, 2008; Oct 1, 2007

initializing multi dimensional arrays in octave

2007-09-03T00:41:00.000-04:00

In octave, multi dimensional arrays can be initialized using the reshape function. As an example, consider the following script.


$cat multidimensional_array.m
1;
a = zeros(1, 24);
for i=1:24
  a(i) = i;
end
a
b = reshape(a, [4 3 2])

The output looks as follows


$octave -q
octave:1> multidimensional_array
a =

 Columns 1 through 16:

    1    2    3    4    5    6    7    8    9   10   11   12   13   14   15   16

 Columns 17 through 24:

   17   18   19   20   21   22   23   24

b =

ans(:,:,1) =

    1    5    9
    2    6   10
    3    7   11
    4    8   12

ans(:,:,2) =

   13   17   21
   14   18   22
   15   19   23
   16   20   24



octave:2>

thecarpcstore website is down

2007-08-29T13:11:00.000-04:00

$date
Wed Aug 29 13:16:35 EDT 2007

In case you do not know, the support forum for complainterator hosted at http://thecarpcstore.com/phpbb2/ is currently down due to a massive DDoS attack. This is the second time spammers have DDoSed complainterator forums. On a positive side, this shows what an enormous effect complainterator reports are having in shutting down spammer's websites. Good job complainterator! You rock!

Related Links :

http://complainterator.com/news.html
http://weblog.complainterator.com/

gmail and orkut got hacked or what?

2007-08-14T20:30:00.000-04:00

$ date -R
Tue, 14 Aug 2007 20:34:30 -0400

Am I seeing this correctly? Did someone really manage to hack into google's servers? Some of google's popular websites such as gmail, Orkut seem to be down. I assume it is a temporary problem (a DDOS attack?). Whatever it is, it is impressive to see some non-english garbage on these popular websites.

Oh, I almost forgot, here are the screenshots for posterity :-)

tabs inside krusader

2007-07-17T13:59:00.000-04:00

Krusader is a very nice file manager with lots of features. One thing that I find useful everyday is its ability to have multiple directories in different tabs. The following screenshot shows the location of these tabs in both the panes.

Here I am using Debian Etch (Stable), Qt: 3.3.7, KDE: 3.5.5, Krusader: 1.70.1 "Round Robin" . The above screenshot is produced by ksnapshot, edited by kolourpaint.

Special shell variables in bash

2007-06-21T21:01:00.001-04:00

Bash defines some special variables which are useful while writing shell scripts. They are


$0       = Filename of script
$1       = Positional parameter #1
$2 - $9  = Positional parameters #2 - #9
${10}    = Positional parameter #10
$#       = Number of positional parameters
"$*"     = All the positional parameters (as a single word)[*]
"$@"     = All the positional parameters (as separate stings)
${#*}    = Number of command line parameters passed to script
${#@}    = Number of command line parameters passed to script
$?       = Return value
$$       = Process ID (PID) of the script
$-       = Flags passed to script (using set)
$_       = Last argument of previous command
$!       = Process ID (PID) of last job run in background

[*] Must be quoted, otherwise it defaults to "$@"

Reference :- Appendix B of "Advanced Bash-Scripting guide" by Mendel Cooper, Version 5.0. Debian users can get this document by installing the abs-guide package.


sudo apt-get install abs-guide

which manpage am I looking at?

2007-06-12T23:29:00.001-04:00

Q. which manpage am I looking at?
A.

man -w keyword

gives the filename of the manpage that would be displayed when

man keyword

is entered at the commandline.

To get a list of all plausible manpages use

man -aw keyword

The -w option works for info also.

Q. which info page am I using?
A.

info -w keyword

gives the path of the info file that would have been displayed if the command "info keyword" is used.

Ref :- The manpages of man, info!

Stapling paper

2007-06-05T13:47:00.000-04:00

When stapling a bunch of letter or a4 sized sheets, staple sizes can be chosen using the following table.


Number of sheets    Stack height      Staple size
   25                  1/8''             1/4''
   60                  1/4''             3/8''
   90                  5/16''            1/2''
  160                  9/16''            3/4''

I assumed the thickness of paper is roughly around 0.1 mm (which might not always be correct!).

Disclaimer: The above info is just a guideline. Use it at your own risk. I am not responsible for any losses that you may incur due to using it.

updating texmacs to new upstream release

2007-05-15T19:16:00.000-04:00

As of Tue, May 15, 2007 Debian contains the following versions of Texmacs.


Stable (Etch)   : 1:1.0.6-10
Testing (Lenny) : 1:1.0.6-11
Unstable (Sid)  : 1:1.0.6.9-4

On my system, I am using Debian Etch, texmacs 1.0.6.9-2. Couple of days back, texmacs released 1.0.6.10. As a maintainer of this package, I want to build the 1.0.6.10 package which can eventually be uploaded to Debian Sid. This document provides a recipe of commands to achieve this goal.

Here I assumed that you are using pdebuild for the first time. If you have used it before, skip the appropriate steps.


$cp /usr/share/doc/pbuilder/examples/pbuilder-distribution.sh ~/bin/pbuilder-sid
$mkdir -p ~/pbuilder/result
$sudo aptitude install cdebootstrap
$pbuilder-sid create # if second time, use 'pbuilder-sid update'

$cat ~/bin/pdebuild-distribution.sh
#!/bin/sh

DISTRIBUTION=`basename $0 | cut -f2 -d '-'`
BASE_DIR="$HOME/pbuilder"
pdebuild --buildsourceroot fakeroot \
  --buildresult $BASE_DIR/result \
  --auto-debsign \
  -- --basetgz $BASE_DIR/$DISTRIBUTION-base.tgz \
  --distribution $DISTRIBUTION $@

$cp ~/bin/pdebuild-distribution.sh ~/bin/pdebuild-sid
$chmod +x ~/bin/pdebuild-sid

$cd ~/practice/

Obtain the latest source from texmacs website


$wget ftp://ftp.texmacs.org/pub/TeXmacs/targz/TeXmacs-1.0.6.10-src.tar.gz

Rename the upstream sources


$tar xzvf TeXmacs-1.0.6.10-src.tar.gz -C .
$mv TeXmacs-1.0.6.10-src texmacs-1.0.6.10
$tar czvf texmacs_1.0.6.10.orig.tar.gz texmacs-1.0.6.10
$rm -rf TeXmacs-1.0.6.10-src.tar.gz texmacs-1.0.6.10
$ls texmacs*
texmacs_1.0.6.10.orig.tar.gz

Obtain the latest sources available in Debian Sid


wget http://ftp.debian.org/debian/pool/main/t/texmacs/texmacs_1.0.6.9.orig.tar.gz
wget http://ftp.debian.org/debian/pool/main/t/texmacs/texmacs_1.0.6.9-4.dsc
wget http://ftp.debian.org/debian/pool/main/t/texmacs/texmacs_1.0.6.9-4.diff.gz

Create the corresponding Debian source for 1.0.6.10


$dpkg-source -x texmacs_1.0.6.9-4.dsc
$cd texmacs-1.0.6.9/
$uupdate -u ../texmacs_1.0.6.10.orig.tar.gz
New Release will be 1:1.0.6.10-1.
-- Untarring the new sourcecode archive ../texmacs_1.0.6.10.orig.tar.gz
Success!  The diffs from version 1:1.0.6.9-4 worked fine.
Remember: Your current directory is the OLD sourcearchive!
Do a "cd ../texmacs-1.0.6.10" to see the new package
$cd ..
$rm -rf texmacs-1.0.6.9/

Update the changelog and do other necessary stuff


$cd texmacs-1.0.6.10/debian/
$dch
...
$cd ..
...

Build the package. The final packages will be in ~/pbuilder/result


$pdebuild-sid
$cd ~/pbuilder/result
$ls texmacs*1.0.6.10*
texmacs_1.0.6.10-1.diff.gz  texmacs_1.0.6.10-1_i386.changes  texmacs_1.0.6.10.orig.tar.gz
texmacs_1.0.6.10-1.dsc      texmacs_1.0.6.10-1_i386.deb      texmacs-common_1.0.6.10-1_all.deb
$linda texmacs_1.0.6.10-1.dsc
$lintian texmacs_1.0.6.10-1.dsc

gnuplot with GNU readline and history support

2007-04-24T11:02:00.000-04:00

By default, the gnuplot packages in Debian are not built with libreadline (GNU readline). This is due to licensing issues (see /usr/share/doc/gnuplot/README.Debian for more info). Having the libreadline support is useful as it enables tab completion of file names inside gnuplot. Using GNU readline, one can also access the commands used in previous gnuplot sessions. The recipe for recompiling the gnuplot packages (in the Debian way) with support for GNU readline and history file is given below.


$cat ~/makefiles/gnuplot.install
#add the following or similar entry into the /etc/apt/sources.list
deb-src http://ftp.us.debian.org/debian/ etch main contrib non-free
# other possible entries look like
# deb-src http://ftp.us.debian.org/debian/ unstable main contrib non-free

# install packages necessary for building gnuplot
sudo apt-get install fakeroot
sudo apt-get build-dep gnuplot
# see the versions of gnuplot available
rmadison gnuplot
# I decided to use gnuplot 4.0.0-5

# go to the place where you normally compile packages
cd /home/software/compileHere/gnuplot

# (optional) move files from previous versions/compilations if they exist
# mv gnuplot-4.0.0/ /tmp
# (optional) move old binary deb files also if necessary
# mv gnuplot*deb /tmp

apt-get source gnuplot=4.0.0-5
dpkg-source -x gnuplot_4.0.0-5.dsc
cd gnuplot-4.0.0/debian/

# Edit the file named "rules" and change
--without-gnu-readline
      TO
--with-readline=gnu

# Enable the history file by adding
--enable-history-file

cd ..
dpkg-buildpackage -us -uc -rfakeroot
cd ..

ls gnuplot*deb
gnuplot_4.0.0-5_all.deb      gnuplot-nox_4.0.0-5_i386.deb
gnuplot-doc_4.0.0-5_all.deb  gnuplot-x11_4.0.0-5_i386.deb

sudo dpkg -i gnuplot*deb

apt-cache showsrc gnuplot

calculate md5sums in windows

2007-04-20T23:55:00.000-04:00

A free, open source software called winMd5Sum is available from http://nullriver.com/winmd5sum . This software can be used to compute md5sum values of files.

tested on : Windows XP

recipe for building texmacs package with pdebuild

2007-04-14T22:19:00.000-04:00

As of Fri Apr 13, 2007, the stable branch of Debian (Etch) carries texmacs 1:1.0.6-10, unstable branch of Debian (Sid) carries texmacs 1:1.0.6-11 . Assuming that pdebuild is used for the first time, the following recipe can be used to build the unstable's texmacs packages on a machine running Debian Etch (stable).

$cp /usr/share/doc/pbuilder/examples/pbuilder-distribution.sh ~/bin/pbuilder-sid
$mkdir -p ~/pbuilder/result
$sudo aptitude install cdebootstrap
$pbuilder-sid create # if second time, use 'pbuilder-sid update'

$cat ~/bin/pdebuild-distribution.sh
#!/bin/sh

DISTRIBUTION=`basename $0 | cut -f2 -d '-'`
BASE_DIR="$HOME/pbuilder"
pdebuild --buildsourceroot fakeroot \
  --buildresult $BASE_DIR/result \
  -- --basetgz $BASE_DIR/$DISTRIBUTION-base.tgz \
  --distribution $DISTRIBUTION $@

$cp ~/bin/pdebuild-distribution.sh ~/bin/pdebuild-sid
$chmod +x ~/bin/pdebuild-sid
$cd ~/practice/
$wget http://ftp.debian.org/debian/pool/main/t/texmacs/texmacs_1.0.6-11.dsc
$wget http://ftp.debian.org/debian/pool/main/t/texmacs/texmacs_1.0.6.orig.tar.gz
$wget http://ftp.debian.org/debian/pool/main/t/texmacs/texmacs_1.0.6-11.diff.gz
$dpkg-source -x texmacs_1.0.6-11.dsc
$cd texmacs-1.0.6
$pdebuild-sid

The commands can be changed accordingly for other packages as well as for distributions other than sid. The ~/bin/pdebuild-distribution.sh performs similar function for pdebuild as /usr/share/doc/pbuilder/examples/pbuilder-distribution.sh does for pbuilder.

Tested on Debian Etch, using pbuilder 0.161

recipe for building texmacs package with pbuilder

2007-04-14T10:24:00.000-04:00

As of Fri Apr 13, 2007, the stable branch of Debian (Etch) carries texmacs 1:1.0.6-10, unstable branch of Debian (Sid) carries texmacs 1:1.0.6-11 . Assuming that pbuilder is used for the first time, the following recipe can be used to build the unstable's texmacs packages on a machine running Debian Etch (stable).

$cp /usr/share/doc/pbuilder/examples/pbuilder-distribution.sh ~/bin/pbuilder-sid
$mkdir -p ~/pbuilder/result
$sudo aptitude install cdebootstrap
$pbuilder-sid create  # if second time, use 'pbuilder-sid update'
$cd ~/practice/
$wget http://ftp.debian.org/debian/pool/main/t/texmacs/texmacs_1.0.6-11.dsc
$wget http://ftp.debian.org/debian/pool/main/t/texmacs/texmacs_1.0.6.orig.tar.gz
$wget http://ftp.debian.org/debian/pool/main/t/texmacs/texmacs_1.0.6-11.diff.gz
$pbuilder-sid build texmacs_1.0.6-11.dsc

The commands can be changed accordingly for other packages as well as for distributions other than sid. More info can be found at /usr/share/doc/pbuilder/pbuilder-doc.html

Tested on Debian Etch, using pbuilder 0.161

executing octave scripts

2007-04-11T23:22:00.001-04:00

Using Octave 3.0.1, bash 4.1.5(1)-release on Debian Squeeze (stable)

$cat even_odd.m
# prevent Octave from thinking that this is a function file
clear;

function even_odd1(m)
# use bitand instead of mod to figure out if a number is odd or even
# if (mod(m, 2) == 1)
if (bitand(m,1))
 printf("%d is odd\n", m)
else
 printf("%d is even\n", m)
endif
endfunction

n = 25
even_odd1(n)
n = 30
even_odd1(n)

The above octave script can be run
1. Directly at the command line by doing

$octave -qf even_odd.m
n =  25
25 is odd
n =  30
30 is even

2. Inside Octave by doing

$octave -qf
octave:1> even_odd
n =  25
25 is odd
n =  30
30 is even
octave:2> n
n =  30

The advantage of first method is that no interaction is necessary. Useful for well tested scripts. The advantage of second method is that variables can be accessed even after the script is executed. Useful while debugging.

3. Source the script inside Octave

$octave -qf
octave:1> source("./even_odd.m")
n =  25
25 is odd
n =  30
30 is even

This approach comes in handy if the name of the script contains any special characters (ex:- '-' hyphen) or if the script has to be called by its relative path name.

insert page numbers in a texmacs document

2007-04-10T01:17:00.000-04:00

To insert page numbers inside a texmacs document, do


Document -> Page -> Type -> Paper
Document -> View -> Page Layout -> Show header and footer

copy paste code into blogger

2007-04-08T22:13:00.000-04:00

The difference between pasting some random text and pasting source code is that, it is necessary to preserve the formatting (indentations etc.,) when pasting the source code. If you would like to list some program inside the articles posted via blogger, then you can do the following:

Convert all the tabs in the program to spaces. While this step is optional, I suggest this since there would be no unwanted surprises with tabs in the final document. If you are using a good editor such as vim, this takes less than a minute.
Go to "Edit Html" tab when editing the post
Put your code inside

<pre class="verbatim" xml:space="preserve">
```
  ...
```
</pre>
tags. That's it.

Google groups feature suggestions - 1

2007-04-05T18:05:00.000-04:00

Today I suggested the following feature to google groups at http://groups.google.com/support/bin/request.py?contact=1

I am the maintainer of a group called xxxx. For some reasons, I have to allow non members to post to this group. So in the group settings, I chose "Anyone can post" and checked the "Hold messages from non-members for moderation". However due to this, I am receiving enormous amounts of spam at http://groups.google.com/group/xxxx/pendmsg

This is, as such, not a problem. The main problem is that I am not able to view the full headers of these pending messages. Currently, I can see only the body and subject of the pending message. Could you please allow moderators to see full headers of the pending messages? That way I can report these spams to knujon, spamcop etc.,

exiting full screen modes

2007-03-27T15:34:00.000-04:00

Q. How to exit the full screen mode in VNC viewer?

A. Inside the vnc session press < F8 > and then choose "Exit Viewer". Tested this on xvnc4viewer 4.1.1+X4.3.0-2 , running on Debian Etch (currently testing).

Q. How to exit the full screen mode in NX?

A. Inside the nxclient session, go to the top right corner. Left mouse clicking there will iconify the NX session. Tested this on nxclient 2.1.0-17, running on Debian Etch (currently testing).

Related links :-

http://wiki.archlinux.org/index.php/FreeNX

search for one word and exclude another word in vim

2007-03-26T14:05:00.000-04:00

In vim, to find all the lines containing the word 'condition' (without the quotes) and to exclude those lines containing 'condition number', install the LogiPat plugin available at http://vim.sourceforge.net/scripts/script.php?script_id=1290

The sample command looks like

:LP "condition" & !"condition_number"

Related links

Download and installation instructions http://vim.sourceforge.net/scripts/script.php?script_id=1290
LogiPat on Author's homepage http://mysite.verizon.net/astronaut/vim/index.html#LOGIPAT
Discussion on vim mailing list http://tech.groups.yahoo.com/group/vim/message/78897

Disable system bell

2007-03-19T23:33:00.002-04:00

1. The annoying system beep on tab completions can be disabled in Debian by adding the following lines to ~/.inputrc

$cat /home/rajulocal/.inputrc
# do not bell on tab-completion
set bell-style none
set bell-style visible

Unlike "xset b 0", the above hack works even if you are not running X.

Tested on Debian Etch (currently stable), on

$bash --version
GNU bash, version 3.1.17(1)-release (i486-pc-linux-gnu)
Copyright (C) 2005 Free Software Foundation, Inc.

2. To disable the annoying bell sound in vim, gvim add the following line to ~/.vimrc

set vb t_vb=

More info for vim can be found at

:help visualbell

Tested on Debian Etch (currently stable), on vim 7.0.122

3. To disable the system bell sounds in tcsh, add the following line to ~/.cshrc

set nobeep

Tested it on Solaris 8, tcsh

inserting a horizontal line in texmacs

2007-03-18T15:50:00.000-04:00

To insert a horizontal line in texmacs type

  \hrule

and press <enter>.

list of all Debian machines

2007-03-18T05:43:00.000-04:00

A complete list of all Debian machines is available at http://db.debian.org/machines.cgi .

convert mp3 to wav

2007-03-06T20:00:00.000-05:00

place the following script in ~/bin and call it mp3towav.


guest@kusumanchi:~/bin$ cat mp3towav
#! /bin/sh

# bash script to convert .mp3 files to .wav files
# works even if the files have spaces in their names.
#
# Author : Kamaraju Kusumanchi
# Email  : kamaraju at gmail dot com
#
# Usage : cd into the directory containing .mp3 files and then execute
# this.
#
# Ref :- Linux Multimedia Hacks, Tips & Tools for Taming Images, Audio and
# Video by Kyle Rankin, pg-100
#

for i in *.mp3; do
lame --decode "$i" "`basename "$i" .mp3`".wav
done

Make the script executable

guest@kusumanchi:~/bin$ chmod +x mp3towav
guest@kusumanchi:~/bin$ ls -al mp3towav
-rwxr-xr-x 1 guest guest 450 2007-03-06 20:19 mp3towav

Cd into the directory containing .mp3 files

guest@kusumanchi:~/bin$ cd /entertainment/telugu_songs/godavari/
guest@kusumanchi:/entertainment/telugu_songs/godavari$ ls -1 *mp3
01 - Ramachakkani Sitaki.mp3
02 - Uppongele Godavari.mp3
03 - Manasavacha.mp3
04 - Manasaa Gelupu.mp3
05 - Tippulu Tappulu.mp3
06 - Andamgaalena.mp3

Run the script

guest@kusumanchi:/entertainment/telugu_songs/godavari$ ~/bin/mp3towav

There will be messages such as

ID3v2 found. Be aware that the ID3 tag is currently lost when transcoding.
input:  01 - Ramachakkani Sitaki.mp3
       (44.1 kHz, 2 channels, MPEG-1 Layer III)
output: 01 - Ramachakkani Sitaki.wav  (16 bit, Microsoft WAVE)
skipping initial 1105 samples (encoder+decoder delay)
Frame#  8878/8859   128 kbps  L  R

The corresponding .wav files will be created once the script completes. The .mp3 files are unmodified.

guest@kusumanchi:/entertainment/telugu_songs/godavari$ ls -1 *wav
01 - Ramachakkani Sitaki.wav
02 - Uppongele Godavari.wav
03 - Manasavacha.wav
04 - Manasaa Gelupu.wav
05 - Tippulu Tappulu.wav
06 - Andamgaalena.wav

Programs like k3b can now be used to burn these wave files onto a CD/DVD.

ఎన్ని సార్లు విన్నా ఇంకా ఇంకా వినాలనిపించే ...

2007-03-06T01:28:00.000-05:00

పల్లవి:
నీల గగనా ఘనవిచలనా ధరణిజా శ్రీ రమణ
మధుర వదనా నళిన నయనా మనవి వినరా రామా!

రామ చక్కని సీతకి అరచేత గోరింట
ఇంత చక్కని చుక్కకి ఇంకెవరు మొగుడంట
రామ చక్కని సీతకి

చరణం 1
ఉడత వీపున వేలు విడిచిన పుడమి అల్లుడు రాముడే
ఎడమ చేతను శివుని విల్లును ఎత్తినా రాముడే
ఎత్తగలడా సీత జడను తాళి కట్టే వేళలొ
రామ చక్కని సీతకి

చరణం 2
ఎర్ర జాబిలి చేయి గిల్లి రాముడేడని అడుగుతుంటె
చూడలేదని పెదవి చెప్పె చెప్పలేమని కనులు చెప్పే
నల్లపూసైనాడు దేవుడు నల్లనీ రఘురాముడు
రామ చక్కని సీతకి

చరణం 3
చుక్కనడిగా దిక్కునడిగా చెమ్మగిల్లిన చూపునడిగా
నీరు పొంగిన కనులలోన నీటి తెరలే అడ్డునిలిచె
చూసుకోమని మనసు తెలిపె మనసు మాటలు కాదుగా

రామ చక్కని సీతకి అరచేత గోరింట
ఇంత చక్కని చుక్కకి ఇంక ఎవరు మొగుడంట
రామ చక్కని సీతకి

ఇందువదనా కుందరదనా మందగమనా భామా
ఎందువలన ఇందువదనా ఇంతమదనా ప్రేమా ??

ఈ పాట "గోదావరి" అను సినిమా లోనిది. వేటూరి గారు రచించారు. గాయత్రి గారు పాడారు. చాలా మంచి పాట కదూ? మీకు కూడా ఇది ఇష్టమేనా?

gnuplot realted links

2007-03-05T18:57:00.000-05:00

Some useful links related to gnuplot

Increase the resolution in splot commands http://learn.tsinghua.edu.cn:8080/2001315450/gnuplot-doc/isosamples.html

various ways of reading man pages

2007-03-05T01:22:00.000-05:00

There are many ways to read man pages in Debian.

man pagename
In konqueror, man:pagename
In vim, :Man pagename
use vman, wman as described in Using vim as a man page reader
In emacs, M-x man
Install man2html and then go to http://localhost/cgi-bin/man/man2html in any browser
xman -notopbox -bothshown &

My experience with knujon

2007-03-04T23:33:00.000-05:00

On March 4, 2007 I came across user damaging spammer provider thread on spamcop forums. I decided to give knujon a try after going through their website.

I registered my gmail address at http://www.knujon.com/register.html after reading their FAQ.

After the registration, I was told to send the junk emails to knujon@coldrain.net

Submitting Junk emails to knujon is explained in http://www.knujon.com/howtosend.html and instructions specific to Gmail are at http://www.knujon.com/howtosend.html#Gmail .

Install python and libgmail which are needed to run the gknujon script at http://www.submanifold.be/triade/misc/gknujon/gknujon.html

# aptitude install python python-libgmail

Get the python script

$ mkdir knujon
$ cd knujon/
$ wget http://www.submanifold.be/triade/misc/gknujon/bin/gknujon.zip
$ unzip gknujon.zip

Go through all the files generated.

$ python gknujon.py -h
provides some help.

Sample command that I use looks like
$ python gknujon.py -l username@gmail.com -p password -r knujon@coldrain.net

See gknujon.bat for sample commands and other options.

The script is really easy to use. The interaction looks like

$ python gknujon.py -l username@gmail.com -p password -r knujon@coldrain.net
Login successful
- 89 unread messages found in spam folder
- downloading spam message (89/89)
- Zipping spam message (89/89)
- Sent report (2/2)
- There are 2 spam reports in your sent mail
Trash the spam reports? (y/n)
or Press Enter to quit: n
- There are 0 SEC-delivery notifications in your inbox
- There are 89 messages in your spam folder
Empty spam folder? (y/n)
or Press Enter to quit: y
trashing (89/89) : Get it !...
Press Enter to quit...

On Mar 10, 2007 I received a personal email address from knujon to which I can forward all my spam emails. The python script is still useful and the only change is in the "reporting address" field passed as an argument to -r.

Received my first report from knujon on Mar 15, 2007, second on Mar 21, 2007, third on Mar 30, 2007 etc.,

Currently my reporting results are

Sites reported by you: 110
Pending Suspensions: 46
Completed Suspensions: 6
Report Date: 5/13/2005

So to conclude, Knujon is definitely doing a great job in eliminating the spammy websites. I will be updating the above statistics as and when I get new reports from Knujon.

Amazing Nike ad

2007-03-04T16:18:00.000-05:00

This is an amazing ad from Nike ( http://www.youtube.com/watch?v=Mpvuz8gg79Q ) involving cricket. With 2007 Cricket world cup matches starting from March 13 IST, it only tells how much everyone is looking forward to it...

useless knowledge

2007-02-25T16:17:00.000-05:00

Some interesting links which I came across

What's the difference between an embassy and a consulate?

Todo:- Sort these links later.

ogg player for Windows

2007-02-24T13:58:00.000-05:00

VLC is a nice media player that can play ogg files on Windows. It is a open source software released under GPL.

Why I needed this?
I use wiktionary to search for meanings of the English words. The pronounciation of the words is stored in .ogg format. VLC can successfully play these .ogg files.

Using vim as a man page reader

2007-02-19T13:19:00.000-05:00

vim, gvim can be used to read man pages. To accomplish this add the following lines to ~/.bashrc file.

# Use vim as a manpage reader
function vman {
  /usr/bin/man $* | /usr/bin/col -bp | /usr/bin/iconv -c | \
  /usr/bin/view -c "set ft=man nomod nolist so=999 ts=8 wrap\
  titlestring=man\ $1" -
}
# Use gvim as a manpage reader
function wman {
  /usr/bin/man $* | /usr/bin/col -bp | /usr/bin/iconv -c | \
  /usr/bin/gview -c "set ft=man nomod nolist so=999 ts=8 wrap\
  titlestring=man\ $1" -
}

After this man pages can be read by using vman or wman. Sample commands look like

guest@kusumanchi:~$ vman rsync
guest@kusumanchi:~$ wman rsync

Tested this on Debian Etch, running vim 7.0.122, gvim 7.0.122, man 2.4.3, iconv 2.3.6.

Advantages of using vim as a man page reader

'marks' can be used to navigate the man pages which can sometimes be quite large. Other pagers such as 'less', 'more' do not have this feature.
vim's search commands, navigation commands etc., can be used. No need to learn another software or another set of shortcuts.
":syn on" gives beautiful colors while reading the man page
Let's say while reading the man page of ssh, you encounter ssh_config(5). Now to read the man page of ssh_config(5), simply place the cursor on that word and do ctrl-]. This will place you at the man page of ssh_config(5).

Sources:

parts of a futon frame

2007-02-18T19:46:00.000-05:00

The following is a Acme Black Metal Futon Frame containing a full size Futon mattress.

The various parts in this picture are

(A) Left Side Panel
(B) Right Side Panel
(C) Cross Braces (2)
(D) Left Hinge
(E) Right Hinge
(F) Upper Mattress Frame
(G) Lower Mattress Frame
(H) Short Bolts (8)
(I) Long Bolts (8)
(J) Medium Bolts (4)
(K) Protective Pads (4)
(L) Metal Washers (8)
(M1) Lock Washers 1/4'' (8)
(M2) Lock Washers 5/16'' (4)
(N) Large Hex Nuts (4)
(O) End Caps (4)
(P) Small Hex Nuts (8)
(Q) Allen Wrench C-Hooks (2)

(S) Standard Full Size mattress

Parts needed for assembling
(T) Allen Wrench
(U) Hex Wrench

Now, in what way is that useful? I have no idea! Just thought it is interesting!

Books on subversion

2007-02-14T11:15:00.000-05:00

The following is a list of books on subversion.

version control with subversion by Ben Collins-Sussman, Brian W. Fitzpatrick & C. Michael Pilato. The online edition is available for free at the above website. Paperback edition is also available.
Pragmatic Version Control Using Subversion, 2nd Edition, by Mike Mason. Amazon has a paperback edition of this book.
Practical Subversion, Second Edition by Daniel Berlin and Garrett Rooney. Amazon has a paperback edition of this book.
Subversion Version Control: Using the Subversion Version Control System in Development Projects (Bruce Peren's Open Source Series), by William Nagel. Amazon carries a paperback edition of this book.

Please let me know if your favorite book on subversion is not listed here. I can add it.

Update1:- A more comprehensive list is available at http://subversion.tigris.org/links.html#books.

Last activity on this article : March 12, 2007

last drafts of Fortran 95/2003 standards

2007-02-08T15:33:00.000-05:00

The last draft of Fortran 95 standard can be downloaded from
http://j3-fortran.org/doc/year/97/97-007r2/pdf/97-007r2.pdf

The last draft of Fortran 2003 standard can be downloaded from
http://www.j3-fortran.org/doc/year/04/04-007.pdf

Relavent links:

Richard Maine's comments in http://groups.google.com.au/group/comp.lang.fortran/browse_frm/thread/bdbed3abf08af66 explain how close the latest draft and official standard are for Fortran 95.
http://groups.google.com.au/group/comp.lang.fortran/browse_frm/thread/40886f321c616621 is the thread from which the above info is gleaned.

input telugu characters in firefox

2007-01-26T18:12:00.000-05:00

Reading telugu characters in firefox is good, but if you can write in telugu it would be much more cool! This, for example, would come in handy when searching in google for documents containing certain telugu words, when writing telugu scraps in orkut etc.,

Install the "Indic input Extension" from https://addons.mozilla.org/firefox/3972/
Notice the small box on the bottom of firefox that says "Default Input"
Go to http://te.wikipedia.org/wiki/Wikipedia:Configuring_on_Linux and read about various ways of inputting telugu characters
If you can touch type fast in English, I suggest you choose "తెలుగు - RTS" option to write telugu characters
use "ctrl+space" to alternate writing in English and Telugu.

The following screenshot shows how to select "తెలుగు - RTS" and search for documents containing "తెలుగు" in them.

Tested on Debian Etch (testing), firefox 1.5.dfsg+1.5.0.7-2, Indic Input Extension 1.0

switched to the new blogger version

2007-01-19T23:37:00.000-05:00

Today I upgraded my blogger to the newer version and the migration went pretty smoothly! The advantages include

I can use just my google account to log in! Cool! One less password to remember!
There is no “Publishing…” spinner anymore! Now when a new post is made, there is no need to republish; The blog gets updates automagically! Sweet!

Todo :- Previously I customized my template quite a bit. I have to upgrade this to the newer version and then customize it again!

watching netflix previews

2006-12-27T12:51:00.000-05:00

By default, watching netflix previews in firefox on Debian Etch (currently testing) gives "click here to download plugin" error. The error looks like

Even if you click on the green button nothing productive happens. Firefox just complains that "No suitable plugins were found". Duh!

The solution is to install the mozilla-mplayer package.

rajudell:~# cat /etc/apt/sources.list
deb http://ftp.us.debian.org/debian/ etch main contrib non-free
deb-src http://ftp.us.debian.org/debian/ etch main contrib non-free

deb http://security.debian.org/ etch/updates main contrib non-free
deb-src http://security.debian.org/ etch/updates main contrib non-free

deb http://www.debian-multimedia.org etch main

rajudell:~# aptitude update

rajudell:~# aptitude install mozilla-mplayer

At the "Do you want to continue? [Y/n/?]" prompt, just press 'y' and then 'Enter'. Pressing 'Enter' alone will also work as 'Y' is the default here.

Once you do this, the videos embed nicely in firefox. The audio works fine too!

Hope that helps all you multimedia folks. Tested this on Debian Etch (testing) running firefox (1.5.dfsg+1.5.0.7-2), mozilla-mplayer (3.21-1). As usual, comments on whether the article has been helpful, errors, feedback etc., are most welcome.

list of all debian developers

2006-12-26T21:36:00.000-05:00

A complete list of all Debian Developers (DDs) can be found at http://qa.debian.org/developer.php?all=1 . The entries are sorted according to email address.

Burning ISO files in Windows XP

2006-12-23T12:42:00.000-05:00

Imagine you are on a machine running Windows XP. Now you want to install Debian on that and make it a dual boot so that you can use both Windows and Debian as and when the need arises. There are many ways to do this. Most people start by downloading the net install image from http://www.debian.org/devel/debian-installer/ . However Windows XP, AFAIK, does not come with an iso image burning software. In order to burn the .iso file on to a CD/DVD, you can use any one of

softwares.

Both softwares are free (but not opensource). The only problem with "CDBurnerXP Pro" is that it does not work with files larger than 4.2 GB. So you cannot really burn a DVD images of say Etch distribution which are normally greater than 4.2 GB and less than 4.7 GB. However, "DeepBurner Free" has no such restriction.

According to http://www.cleansoftware.org/utility/#cddvd , "CDBurnerXP PRO" is also free from adware, spyware etc.,

PS: I was not able to find any free CD/DVD burning software for Windows XP, which has the facility to burn iso files and is released under GPL or is opensource. If you know of any, please let me know.

Uncle Ezra now has an RSS feed!

2006-12-21T14:06:00.000-05:00

Sometime back I suggested to Uncle Ezra that having an RSS feed for their website would be nice. Now they have one. Cool! The feed is at http://ezra.cornell.edu/feed.php. I already added it to my RSS reader and it is working perfectly! Thank you Uncle Ezra!

Jack Bauer Vs Santa

2006-12-20T12:08:00.000-05:00

For the fans of 24, here is a nice version of what happens in the world of Santa! This video is awesome. You gotta check it out!

http://www.youtube.com/watch?v=6vyw6DXkOpA

update1 : On Feb 2, 2007 I found that this video has been removed from youtube! Sorry folks!

atom vs rss feeds

2006-11-28T10:48:00.000-05:00

For some reason google reader is not working correctly with the atom feed of this blog. Even when I updated some articles on the blog, the reader is not showing the new articles. So now I created a RSS feed for this blog. Both feeds are available in the Links section of the sidebar. Use the one that works for you. Please let me know if you are still having problems reading this blog ...

running ssh from web browsers

2006-11-28T09:35:00.000-05:00

It is possible to access your Debian Linux machine from a Windows machine using just a web browser + ssh. In order to do this, start the sshd daemon on the Debian Linux machine by using either

$sudo /etc/init.d/ssh restart
Restarting OpenBSD Secure Shell server: sshd.

or by doing

$wajig restart ssh
Restarting OpenBSD Secure Shell server: sshd.

This will restart the ssh server if it is not running already. Next on the windows machine go to http://www.ece.osu.edu/ssh to run the ssh client. That's it!

Tested on Debian Etch (testing) running ssh 4.3p2-2, windows xp running firefox 1.5.0.8

Useful links:

Ithaca DMV office

2006-08-28T10:31:00.000-04:00

Once in a while, some of my friends ask me about where DMV office in Ithaca is etc., Instead of repeating the answers again and again, I thought it is better to summarize the info in my blog.

Address

301 Third Street
Ithaca, NY 14850

Ph : 607-273-7187
M-F 8:30 am - 4:30 pm
CDL testing until 12:00 pm
Written testing until 4:00 pm
TCAT Buses : Bus no. 13 from commons
Relevant links

If any of the above information is incorrect or if something else can be included etc., please email kamaraju at gmail dot com. If you found this information useful, please leave a comment saying so and that will make my day :-)

gmail feature suggestions - 6

2006-07-31T00:56:00.000-04:00

Today I suggested the following feature to gmail at https://services.google.com/inquiry/gmail_suggest/

Currently there is no facility to forward an email as an attachment. At present gmail forwards email only as "inline". The "forward as an attachment" option would be useful, for example, if one wants to report spam email to spamcop .

Another related feature that would nice to have is the ability to select multiple emails and forward all of them as attachments to a single address in one go. This, for example is possible in thunderbird email client and is very useful when reporting spam emails to spamcop .

gmail feature suggestions - 5

2006-07-17T12:47:00.000-04:00

Today I suggested the following feature to gmail at https://services.google.com/inquiry/gmail_suggest/

Currently when I enter a search expression in gmail, it does not search in all the headers of the email. An option to allow searching of all the headers would be useful, for example, to search for email coming from a particular IP address etc.,

gmail and spamcop vs bluebottle

2006-06-28T19:48:00.001-04:00

I have a gmail address which I exclusively use for mailing list subscriptions, news letters etc., But since the mailing lists that I subscribe to are archived and are searchable by google this gmail address became a haven for spammers who harvest email adresses from these mailing list archives. It reached such a state that I was getting around 100 spam emails everyday.

Normally, gmail does a good job of filtering these spam emails and puts them nicely in a separate folder/label called spam. But there are couple of problems

Once in a while there are couple of emails which are spam but gmail's spam filters are not smart enough to filter them out.
There are some false-positives. That is email which is good, but gmail's spam filters thought they were spam and kept them in the spam folder.

The first issue is easy to solve - Simply train the spam filter by reporting it as spam. The second issue is the real show stopper. I have to wade through hundreds of spam emails to figure out if there are any false positives in there. Adding an email address to the 'contacts list' will ensure that an email from that sender will not end up in the spam folder at a later point of time. However it does not eliminate their occurrence in the future from some other email address. This whole process of checking the spam folder for false positives, adding the email IDs to contacts list is not only time consuming but also frustrating due to its very own mundane nature.

I googled around and found spamcop ( http://www.spamcop.net/ ). After registering, users can report their spam emails to spamcop. Based on a complicated algorithm spamcop then lists the IP addresses responsible for spamming. This list is called SCBL (spam cop blackhole list). If you are interested in knowing this "complicated algorithm" or if you want to know more about how spamcop works, you can read the documentation available on the spamcop's website.

The idea is that once you have a fairly recent SCBL list, an email server administrator can use that to identify spam. When the spam is identified, the administrator can then either reject or tag the spam email. But since I am using gmail, the SCBL list is of no use to me. However, I started reporting spam to spamcop's website using the web interface hoping that it might help others using the SCBL. Since reporting each spam email takes roughly 0.5 minutes, I was spending an hour a day just to report spam. The time would have been well spent, if the spam actually decreased. But even after trying the whole thing for 2 months, spam has only increased and has not decreased even by a single bit.

Does that mean that spamcop does not work? No. Spamcop does work - well, to some extent atleast. To understand what I mean, it is necessary to understand how spammers operate.

Spammers usually do not own their own machines per se. They hack into insecurely configured machines on the net and start sending spam from them. Now if the ISP hosting these machines is a "good ISP" then they care about spam coming from their network. One such example is http://www.uk.easynet.net/ . Once I received some spam emails from a machine whose IP address is 217.204.66.154 . This IP address belongs to easynet Ltd. I reported those spam emails to spamcop which in turn forwarded the "spam reports" to the abuse team at uk.easynet.net . They immediately recognized the problem and took necessary action so that no spam email emanates from that machine. This is just one of the success stories of spamcop in action. There could be many more.

But what if the ISP is not a "good ISP"? If the ISPs do not care about spam coming from their networks then the spamcop method does not work for gmail users. The gmail users will still be receiving spam from machines owned by these "bad ISPs". So "spamcop + gmail" approach has some loopholes through which spam will manage to flow into the gmail's account.

Googling again, I came up with bluebottle ( http://www.bluebottle.com ) which is essentially a Challenge-Response system. The idea is that, if you send an email to the bluebottle's address you will get a challenge asking you to verify yourself. Only if the sender verification process succeds, I receive the email in my Inbox. Pretty cool Uh! Initially one would think so. But the C-R system has its own drawbacks. These drawbacks can easily be found by googling. But the upside is that one does not see any spam whatsoever in their Inboxes. So I need not wade through hundreds of spam emails looking for false-positives.

In bluebottle, emails from unverified senders go into a 'pending' folder. They stay there for a week, after which they will be deleted automatically. The messages in the 'pending' folder will go to the Inbox either if the sender verifies them or if I manually approve the message. The manual approval process eliminates the notorious 'C-R C-R deadlock'.

To quote some numbers, my gmail account typically receives 100 spam emails a day where as I receive 25 ham emails per day. So the ratio of spam/ham is 4. Yahoo's spam/ham ratio is even worse. Compared to this, in the pending folder of my bluebottle's account, I receive about 25 emails per day (waiting to be approved) of which around 5 turn out to be spam. The ratio of spam/ham is 5/20 = 0.25 . Coupled with 'no false positives', this makes bluebottle very attractive.

There are many drawbacks with bluebottle as well!

While gmail offers more than 2GB, yahoo offers 1 GB, bluebottle's free account offers only 0.25 GB.
Only Inbox folder can be POPped in bluebottle. In gmail, emails under any label can be POPped. Better yet, gmail offers IMAP facility which is much more useful.
There are ads attached to every email sent through bluebottle's SMTP. This is very annoying.
People sending the email do not usually answer challenges. So most of the messages have to be approved manually.
The bluebottle's servers (both POP and SMTP) are not as reliable/fast as gmail's servers.
There is no facility to search the CC fields of emails in bluebottle. Bluebottle's search facility is limited to the "To:" header and does not extend to the "Cc:" header.

One area where I had doubts about bluebottle's approach is the mailing list subscriptions. Will I be able to subscribe to mailing lists like debian-user through the bluebottle's email address? Will there be any problems? So far the results are somewhat it mixed. It works with some email lists (ex:- debian-user, debian-devel, debian-qa etc.,) and does not work with some other mailing lists (ex:- vim, texmacs-users, subversion-users etc.,).

Whitelisting all the emails from debian-user mailing list to your bluebottle's account is as simple as adding the following email addresses to your "Allowed Senders" list.

debian-user-request@lists.debian.org

However adding vim@vim.org to the "Allowed Senders" list does not whitelist all the emails from vim mailing list. The unverified senders who send email to vim mailing list still receive challenges.

So far, in terms of spam inconvenience, false positives etc., I can say that using bluebottle's free email account has yielded better results than using gmail+spamcop or gmail alone. But I feel that bluebottle's or any other C-R system is a short term solution to spam and does not scale well for large number of users. Spamcop's approach though interesting, needs some modifications for it to be effective. For now, I am adopting both the approaches - use bluebottle's address for mailing lists, report spam from gmail to spamcop as and when time permits. Only time will tell which one would succeed!

Comments, criticisms, typos, suggestions etc., can be sent to kamaraju at gmail dot com.

Last updated : Apr 10, 2008.

Google applications that I use

2006-06-19T14:04:00.000-04:00

In no particular order, these are the google applications that I frequently use.

mail.google.com

pages.google.com

spreadsheets.google.com

groups.google.com

scholar.google.com

maps.google.com

video.google.com

talk.google.com

adsense.google.com

docs.google.com

installing packages from marillat's repository

2006-06-14T14:41:00.000-04:00

Marillat's repository contains useful debian packages like mplayer, acrobat reader etc., To install let's say libdvdcss2 package from this repository follow these instructions.

1) Go to the end of http://debian.video.free.fr/

2) Copy the appropriate repository address. For example if you are running Debian Sid (unstable) on an i386 machine then you need to copy this line

deb http://www.debian-multimedia.org sid main

3) paste this line into /etc/apt/sources.list . Note that you need to have root permissions to edit the sources.list file

4) update the sources by doing

wajig update

5) Now install the necessary package(s) by running

wajig install libdvdcss2

This method is much more easier compared to downloading the package and installing it by hand using 'dpkg -i'.

Comments/corrections/criticisms/typos etc., can be directed to kamaraju at gmail dot com

Getting a GUI

2006-05-31T00:45:00.000-04:00

After installing Debian, often one is left with just a command line prompt waiting for the user to enter login and password. If you are coming from Microsoft Windows environment, this command line prompt looks similar to the DOS prompt. This article explains how to get a GUI environment after installing basic Debian.

Since I have experience only with KDE, I will try to focus just on installing KDE.

In order to get a working GUI as quickly as possible, run the following two commands as root.

apt-get update
apt-get install xorg kde kdm

This will fetch all the required packages necessary to run KDE.

During the installation of the packages, there will be some questions regarding configuring X environment etc., Once you finish answering all the questions, you will get a working KDE environment.

Last activity: Jan 24, 2007

control kmail sounds

2006-05-26T16:11:00.000-04:00

In kmail, the default keyboard shortcut to send messages is ctrl-Enter. When this command is entered, a pop up comes giving the options "Send Now", "Send Later" and "Cancel". However, When this popup comes up, an annoying sound is played. To get rid of this sound use

kcontrol -> Sound & Multimedia -> System Notifications

In the tab on the right hand side, select

"A warning message is being shown"

and remove the sound icon by clicking on corresponding icon. Then click on Apply button on the bottom right hand side and close the kcontrol window.

move tabs in konqueror

2006-05-16T20:26:00.000-04:00

On the tab that you would like to move, click with the middle mouse button and then drag it to the required place.

This tip has been tested on a Debian Sid machine running

$konqueror --version
Qt: 3.3.6
KDE: 3.5.2
Konqueror: 3.5.2

How to view changelogs of a Debian package over web

2006-05-07T21:28:00.000-04:00

Every installed package on a Debian machine has changelog.gz and/or changelog.Debian.gz depending on whether the package is specific to Debian or not. These files are stored in /usr/share/doc/packagename.

For example, since firefox is not specific to Debian, it has both changelog.gz and changelog.Debian.gz . OTOH, since wajig is specific to Debian, it only has changelog.gz. There is no changelog.Debian.gz for wajig.

changelog.gz refers to changes done by the upstream author where as changelog.Debian.gz refers to changes done by the Debian maintainer.

/usr/share/doc/packagename/changelog.Debian.gz contains the changelog for the installed package. If a new version of package is available in Debian repositories then sometimes it is useful to have a look at just the new changelog without downloading the whole package. In order to see the latest changelog of a package, you can use

http://packages.debian.org/changelog:packagename

So to see changelog of the latest firefox package available in Debian repositories use

http://packages.debian.org/changelog:firefox

As usual, Comments and suggestions can be emailed to kamaraju at gmail dot com.

subversion migration

2006-04-30T01:55:00.000-04:00

On Oct 17, 2005 I posted about gcc being converted from cvs to subversion.

http://malayamaarutham.blogspot.com/2005/10/gcc-cvs-svn.html

In that post, I also stated that I should be migrating to subversion. Well, It finally happened after about 6 months :-) I finally created a subversion repository and migrated couple of my previous projects to subversion. Things look very cool so far!

The documentation for svn is available at http://svnbook.red-bean.com/

In particular, I was impressed with http://svnbook.red-bean.com/nightly/en/svn.intro.quickstart.html which gives an headstart for CVS users.

Go subversion go! You rock!

bug reports summary

2006-04-20T15:22:00.000-04:00

The reports are organized in reverse chronological order so that the latest stay on the top.

Bugs reported and not yet fixed

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=404635 reported on Dec 26, 2006.
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=404535 reported on Dec 25, 2006.
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=404450 reported on Dec 24, 2006.
https://savannah.gnu.org/bugs/?18363 reported on Nov 24, 2006.
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=399903 reported on Nov 22, 2006.
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=399653 reported on Nov 21, 2006.
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=397078 reported on Nov 04, 2006.
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=396802 reported on Nov 02, 2006.
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=393481 reported on Oct 16, 2006.

Bugs reported and fixed (sorted in the order when they are fixed).

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=374023 reported on Jun 16, 2006; fixed by Jan 18, 2007
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=364900 reported on Apr 26, 2006; fixed by Oct 25, 2006
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=363642 reported on Apr 20, 2006; fixed by Jun 03, 2006
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=343969 reported on Sep 30, 2005; fixed by Jun 02, 2006
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=357685 reported on Mar 18, 2006; fixed by Apr 20, 2006

This post is last updated on Jan 18, 2007.

"adsense for search" now included in this blogspot

2006-04-15T12:26:00.000-04:00

Of late, I have been posting a lot of stuff on this blog. Now I am at a stage, where, I cannot recall all the articles/issues/musings that have previously been posted. So, I decided to put a google search box in my blog. This search box is a bit different from the default search box provided by blogger.

The default search box that comes with blogger provides two functionalities:

Search this blog
Search all blogs

But it does not allow me to search the web.

The google search box also provides two functionalities:

Search this blog
Search the whole web

As the second option is useful to me, I decided to have google search box in my blog.

Google calls this search box as "adsense for search". Yesterday, I did some css hacking and now my blog is "adsense for search" compliant. The search bar should appear on the right of this blog in the "sidebar".

Any comments regarding this move are most welcome.

On a related note, Sometime ago, I have included "adsense for content" - ie advertisements in this blog. The related post can be found at

http://malayamaarutham.blogspot.com/2005/11/this-blog-is-now-adsense-friendly.html

raju

gmail feature suggestions - 4

2006-04-10T17:16:00.000-04:00

Please provide instructions for accessing gmail using kmail as the email client. The relevant instructions can go into http://mail.google.com/support/bin/topic.py?topic=1555

Currently there is only http://mail.google.com/support/bin/answer.py?answer=13287

But this is very unclear. Should one use TLS or SSL when using kmail as their MUA? Also kmail provides 6 different authentication mechanisms such as LOGIN, PLAIN, CRAM-MD5, DIGEST-MD5, NTLM, GSSAPI. It is not clear as to what authentication mechanism one should use with kmail.

raju

gmail feature suggestions - 3

2006-03-19T18:33:00.000-05:00

Today I suggested the following feature to gmail at https://services.google.com/inquiry/gmail_suggest/

Whenever I search for a word or a phrase in my gmail account, only 20 results are displayed per page. This is very inconvenient when there are lots of results. I think it would be cool if there are options to display 20 results per page, 50 results per page, 100 results per page, all the search results in one page.

reporting emails from petsupermarket as spam to gmail

2006-03-18T00:48:00.000-05:00

Whenever I post an email to debian-user@lists.debian.org , I get a spam email from AntiSpam UOL . This email looks something similar to

I cannot just mark this message with "report spam", since that will delete the whole thread. I wanted to save the whole thread for later reference, but at the same time I wanted to report this stupid email as spam. To do this, I discovered a work around which might work, if enough gmail users train their spam filter.

In this antispam UOL email, select the "More options" link (towards your right), then click on "Delete this message". The mail will still be there under the Trash label. Now go to the Trash, select this antispam UOL email, choose "Report as spam" under "More actions" menu. That's it.

Captions for the photo please!

2006-03-16T15:08:00.000-05:00

For convenience, you can refer to the male as M, female as F. Leave your captions in the comments!

1) Even the 'King of the Jungle" has to go through it - every day!

2) A wife is a wife!

bugs reported today

2006-03-14T15:55:00.000-05:00

I reported the following bug on Texmacs today. I requested to make the pdf version of the user manual available on the texmacs documentation website http://www.texmacs.org/tmweb/help/manual.en.html . Currently only ps version is available there.

More details can be found at https://savannah.gnu.org/bugs/?func=detailitem&item_id=16090

gmail feature suggestions - 2

2006-03-12T18:24:00.000-05:00

Today I suggested the following feature to gmail at https://services.google.com/inquiry/gmail_suggest/

Currently gmail either shows all the labels or does not show any labels. But there is no way to tell gmail to display 'only the labels with unread emails in them'. If there are lot of labels in one's gmail account, it becomes difficult to see where the unread messages are. In such case, I think this feature would be very handy.

gmail feature suggestions - 1

2006-03-09T20:07:00.000-05:00

Today I suggested the following feature to gmail at https://services.google.com/inquiry/gmail_suggest/

Currently it is not possible to search for emails across different labels. This would be a cool feature to have.

Let me explain it more clearly.

Say I have 10 labels in my email account. Let these be named as label1, label2, label3, ... label10. Now I would like to search for emails which are under label4, label7, label9. Currently this is not possible. But IMHO is a very useful feature to have.

How to generate thumbnails

2006-03-06T14:33:00.000-05:00

To create thumbnails use the -thumbnail option of the convert command. This option preserves the aspect ratio of the picture. So you need to specify just the width or height of your thumbnail.

Sample commands look like

convert -thumbnail 160 original.jpg thumbnail.jpg
convert -thumbnail x160 original.jpg thumbnail.jpg

The first one creates the thumbnail whose width is 160 pixels. The second one creates a thumbnail whose height is 160 pixels.

Ref :- Linux Multimedia Hacks - Tips & Tools for taming images, audio, and video by Kyle Rankin

On Debian GNU/Linux machines, convert command is part of imagemagick package. You can install the imagemagick package using apt-get

apt-get install imagemagick

Feedback, comments, suggestions are most welcome and can be left in the comments field of this blog.

bugs reported today

2006-02-27T17:15:00.000-05:00

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=35463

Bugs reported today

2006-02-22T23:52:00.000-05:00

I reported the following bugs today

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=354032

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=354054

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=354078

definition of Hacker

2006-02-13T21:55:00.000-05:00

Hacker is someone who loves to program and enjoys being clever about it. It does not necessarily mean "someone who breaks into computers".

Source: "Producing Open Source software" by Karl Fogel.

passing function names as arguments in Fortran 90 programs

2006-02-05T03:04:00.000-05:00

Sometimes it is desirable to pass function names as arguments to another function. The following code gives a simple example on doing this in Fortran.


! Author : Kamaraju S Kusumanchi
! Email  : kamaraju@gmail.com
! Last edited : Sun Feb  5 2006
!
! Sample program demonstrating the use of external attribute.  This program
! shows how to pass function names as arguments in Fortran 90 programs.
!
! Compilation and execution steps
! $gfortran passing_functions.f90 -o passing_functions
! $./passing_functions
!  beta =    5.500000
!  beta =    1.500000
!
! I would appreciate any comments, feedback, criticism, mistakes, errors etc.,
!   (however minor they are)
!
module dummy
  implicit none
contains
!------------------------------------------------------------------------------
function func1(a)
  implicit none
  real :: a
  real :: func1

  func1 = a+5
end function func1
!------------------------------------------------------------------------------
function func2(b)
  implicit none
  real :: b
  real :: func2

  func2 = b*3.0
end function func2
!------------------------------------------------------------------------------
function func3(dyn_func, c)
  implicit none
  real :: c
  real, external :: dyn_func
  real :: func3

  func3 = dyn_func(c)
end function func3
end module dummy
!------------------------------------------------------------------------------
program passing_functions
  use dummy
  implicit none

  real :: alpha=0.5, beta
  
  beta = func3(func1, alpha)
  write(*,*) 'beta = ', beta
  beta = func3(func2, alpha)
  write(*,*) 'beta = ', beta
end program passing_functions

format the whole file with vim

2006-01-25T14:51:00.000-05:00

Vim is a powerful text editor. Debian users can install vim using the command

apt-get install vim

To format the whole file using vim, use the command gg=G in the normal mode.

not surprising except for the 100% english part

2006-01-14T12:58:00.000-05:00

You scored as Engineering. You should be an Engineering major!

English

100%

Philosophy

100%

Engineering

100%

Psychology

100%

Mathematics

92%

Theater

83%

Chemistry

75%

Biology

58%

Sociology

58%

Art

58%

Dance

58%

Linguistics

50%

Anthropology

50%

Journalism

42%

What is your Perfect Major? (PLEASE RATE ME!!<3)
created with QuizFarm.com

Nice Joke

2005-12-31T16:48:00.000-05:00

You gotta see this nice little cartoon. Explains beautifully the thinking process of a fellow "Debian addict".

http://mirror7.escomposlinux.org/comic/ecol-160-e.png

overwhelmed with joy

2005-12-27T17:15:00.000-05:00

I was overwhelmed with joy upon seeing my name mentioned in the last issue of the Debian Weekly News (2005). Honestly, I have not done anything except starting the page and adding little bit of info now and then. Hopefully it would pick up and help fellow Debian users.

Now I am even more motivated to work on Debian.

Update 1 :- Looks like I am becoming famous :-) I was mentioned second time in another DWN issue http://www.debian.org/News/weekly/2006/13/ .

getting rid of warning from reportbug

2005-12-25T19:01:00.000-05:00

Recently when I was using reportbug to report a bug against mrxvt, I was presented with a warning

$reportbug mrxvt
*** Warning: master.debian.org is no longer an appropriate smtphost setting for
reportbug; please update your .reportbugrc file.

The warning just mentions that you have to change master.debian.org to something else. But it does not mention "to what you should change"? The answer is in the /usr/share/doc/reportbug/changelog.gz under the changelog entry for version 3.18

In ~/.reportbugrc, You have to change the line

smtphost master.debian.org

to

smtphost bugs.debian.org

Once you do this, the above warning disappears.

My bug on gdb got fixed

2005-12-21T19:25:00.000-05:00

Even though it took 5 months for it to be fixed, Daniel Jacobowitz finally fixed a bug that I reported on July 22, 2005. Now I can use gdb to debug my fortran programs compiled with gfortran. Cool uh!

free stuff for give away

2005-12-20T23:39:00.000-05:00

You might have arrived here after seeing my email in ISSO mailing list. well, I have a couch, lazy boy chair, futon bed, usual bed . Everything is free and you have to arrange your own shipping. I cant guarantee their condition. Look for yourself. If you like them, take it.

You can contact me at 607-342-5538 or by email (kamaraju@gmail.com)

Update1 :- The futon bed is already gone. I will update this blog if something else is claimed.

Update2 :- The spring matress is also gone. So as of now, only the Couch and the lazy boy chair are remaining.

Update3 :- The couch has also been claimed. Now only the lazy boy chair (waiting lazily, I guess :-)) is available.

Combining postscript files

2005-12-06T15:56:00.000-05:00

postscript files (.ps, .eps) can be combined very easily using psmerge. Sample commands look like

psmerge -ocombined.eps file1.eps file2.eps file3.eps file4.eps
psmerge -o/tmp/combined.ps file*.ps

For more details see its man page (man psutils). In Debian psmerge is part of psutils package and can be installed by

apt-get install psutils

list of travel agents

2005-12-03T23:54:00.000-05:00

For those who are planning to travel to India from New York, a list of travel agents in New York is available at http://www.usindiainfo.com/travel_newyork.htm .

Please let me know if there are other such similar links.

replicate just the directory structure

2005-11-21T01:55:00.000-05:00

Let's say you wanted to just copy the directory structure of /opt directory to an usb drive say (/media/usb3/opt) without copying any files between these two directories. Inorder to do this

mount the usbdrive, cd into the destination directory which in this case is /media/usb3

sudo rsync -avzp --delete-after --include "*/" --exclude "*" /opt .

As usual, do not try this without knowing what it does. Use it at your own risk.

Comments/suggestions/feedback etc., are most welcome and you can reach me at (kamaraju at gmail dot com).

wajig's bash_completion has improved

2005-11-18T01:02:00.000-05:00

My wishlist bug against wajig has been fixed in the recent version 2.0.31 . So now bash_completion works on multiple arguments not just on the first argument. Just now updated wajig and it is working Cool!