Linux by Sankar San

Perl-Expect

2007-02-08T16:19:00.000-08:00

It's been a long time since I actually wrote a program to solve a problem. Ditch the previous post, 'cuz I found a much better SSH daemon for Win called FreeSSHD which lets you run it with "ssh host command" just like I wanted. But even with a help page I found on the topic, I was unable to configure it to work without requiring a password, so I decided to finally get down to Expect (something I've claimed to know, tho' I never got it working to simulate a telnet job like I wanted) and found out that this code works!

#!/usr/bin/perl
use Expect;
my $timeout=2;
my $exp=Expect->spawn("ssh xtp2 \"cmd.exe /c dir\"");
$exp->expect($timeout,
[ "password:" => sub { my $self = shift;
$self->send("root123\n")
} ]
);
$exp->soft_close();

SSH on Windows!

2007-01-23T12:39:00.000-08:00

Oh yes, I got this package and actually used PuTTY to ssh to my Windows machine and ran dir! :) rexec would work, but I couldn't find rexecd.

Ubuntu

2006-09-11T05:25:00.000-07:00

Its been all of seven months off this blog, but get ready for its rebirth 'cuz Ubuntu has breathed a new lease of life into my Linux World! All you have to do is enter your postal address here (which is what I did) and they send you free CDs within a month! I'm impressed!!

I cannot but regale you with the exciting new features you have, which leaves Fedora way behind. 6.06 LTS (Long Term Support) was released in June '06. It comes with:

1. Firefox Version 1.5.0.3
Get Google Browser Sync to get all your settings (saved passwords, bookmarks, etc.) from Windows to Ubuntu.

2. Evolution with MS Exchange support
No more entering hajjar server hostnames/IP addresses and obscure username/password combinations to get it working. All it asks for is your OWA (Outlook Web Access) URL and your login/password and tada! Its all there up and running. What's more, the GAL (Global Address List) works.

3. Rhythmbox
iTunes-like music player which has Library, Podcasts, Sharing and even support for your iPod, from which it lets you play off everything (once you have the codecs installed, which I'll describe how to do shortly) even (I suspect) if your PC is not synced with the iPod (!!!)

The first thing you have to do after you've installed it, is to get Easy Ubuntu or Automatix, which gives you all the codecs you need to get started on MP3s, DVDs and whatnot. For this, I faced huge difficulties to configure my HTTP Proxy with Authentication. Finally, I put this in my .bashrc:

export http_proxy=
"http://(workgroup)\\(username):(password)@(proxy):(port)/"
export ftp_proxy=
"http://(workgroup)\\(username):(password)@(proxy):(port)/"

and PHEW! Its working now! Here's a screenshot by the way:

More later...

Hash

2006-02-09T22:05:00.001-08:00

My new teammate is a Mandhala-like Gulti character. Quite fundoo (Thank God I didn't get some dumbass) and (almost;) as fast as I am. I've had a lot of technical quarrels with him and most are left hanging. One conclusive blow from either of us would settle all in one's favor.

We are dealing with associative arrays today at the advanced perl session. My teammate stated that the hash key contains the memory location of the corresponding hash value. I retorted that this need not be true. He was supported by the facilitator too. This SUN docs page cache saved face!

Forgot root password?

2006-02-08T06:22:00.000-08:00

Gaurav gave me this useful tip:

Allow the system to reboot to the GRUB splash screen, and then press "e". Select the line containing "kernel", and press "e" again. GRUB will display the line in edit mode. Add "single" to the end of the line, and press return. GRUB will return you to the previous screen. Press "b" to boot the system into what will now be single user mode. The system will come part of the way up, and then drop you into a root shell - the prompt will look like this: sh-2.05# _
Type "passwd" and set a new password. Type "exit"

[Listening to: Led Zeppelin - Physical Graffiti - Kashmir (8:32)]

SSH without password

2005-11-30T02:05:00.000-08:00

Realised that if they took this page off, we'd be done for, so I've decided to duplicate it here.
Courtesy: Ranga

The following steps can be used to ssh from one system to another without specifying a password.

1.
On the client run the following commands:

$ mkdir -p $HOME/.ssh
$ chmod 0700 $HOME/.ssh
$ ssh-keygen -t dsa -f $HOME/.ssh/id_dsa -P ''

This should result in two files, $HOME/.ssh/id_dsa (private key) and $HOME/.ssh/id_dsa.pub (public key).

2.
Copy $HOME/.ssh/id_dsa.pub to the server.

3.
On the server run the following commands:

$ cat id_dsa.pub >> $HOME/.ssh/authorized_keys2
$ chmod 0600 $HOME/.ssh/authorized_keys2

Depending on the version of OpenSSH the following commands may also be required:

$ cat id_dsa.pub >> $HOME/.ssh/authorized_keys
$ chmod 0600 $HOME/.ssh/authorized_keys

An alternative is to create a link from authorized_keys2 to authorized_keys:

$ cd $HOME/.ssh && ln -s authorized_keys2 authorized_keys

4.
On the client test the results by ssh'ing to the server:

$ ssh -i $HOME/.ssh/id_dsa server

5.
(Optional) Add the following $HOME/.ssh/config on the client:

Host server
IdentityFile ~/.ssh/id_dsa

This allows ssh access to the server without having to specify the path to the id_dsa file as an argument to ssh each time.

Helpful manpages:

* ssh(1)
* ssh-keygen(1)
* ssh_config(5)

File associations in Fedora

2005-10-26T18:15:00.000-07:00

Needed to open MP3 files with XMMS by just double-clicking them in Nautilus, so I looked up on how to change file associations. The Fedora Forum rocks! I learnt its quite a task! Here's how (with mplayer as example):

-> /usr/share/applications/[application_name].desktop
This is the file where "defaults.list" will point to. One of the most important things inside this file is the entry "MimeType=".

E.g: vi /usr/share/applications/mplayer.desktop
[Desktop Entry]
Name=Movie Player
Comment=Play multimedia files and media
Icon=mplayer.xpm
Exec=mplayer %f
Terminal=false
MimeType=video/mpeg;video/x-msvideo;video/quicktime;video/x-ms-asf;video/x-ms-wmv
Type=Application
Categories=Application;AudioVideo;
Encoding=UTF-8

-> /usr/share/applications/defaults.list
This file contains the applications which cause a double-click success. All Mime types will point to a desktop file.

E.g: Separate multiple app names with ;'s.

video/x-ms-asf=mplayer.desktop
video/x-ms-wmv=mplayer.desktop

-> /usr/share/applications/mimeinfo.cache
Contains information in similar form shown for file "defaults.list" in same directory. This file contains ALL associations given to a mime type. There is no need for a specified order of desktop files. E.g: Repeat above

To do the same for XMMS, replace realplayer.desktop with redhat-audio-player.desktop in all these files..

Perfect boot

2005-10-18T13:03:00.000-07:00

Added these lines to my /etc/grub.conf and now its booting Windows too!

title Windows XP
map (hd0) (hd1)
map (hd1) (hd0)
rootnoverify (hd1,0)
makeactive
chainloader +1

Also copied scripts to let everyone connect to the net.
With it, I've gotten mom up to speed as well..

Fedora Core 4

2005-10-16T15:15:00.000-07:00

When I got FC3, I configured it to multi-boot, which caused a terrible problem to crop up later. I didn't want to risk it happening again, so I decided I'd explore the possibilities of installing FC4 without letting it affect my Windows hard drive.

There was only way I could leave the boot sector unchanged; Change the boot-up sequence in the BIOS and install GRUB and FC4 on my secondary hard drive. However, the kernel panicked while booting from the CD, saying "RAMDISK: Couldn't find valid ramdisk image starting at 0." It took me a while to find the fix.

I came across the usual network configuration issue next. I'm using a BSNL DataOne ADSL Internet connection now, with a Huawei SmartAX MT880. I had no idea how to configure it, until I stumbled upon this amazing client!

The next problem was accessing my Windows volumes; NTFS is not supported, as usual. I got that resolved in a jiffy, after which I started on MP3 support and XMMS download. The XMMS site didn't give me any leads for FC4 though.

Thats when I came across YUM, which I'll rate the best thing ever made to help Fedora users! This behaves like a charm unlike up2date, probably thanks to the BSNL PPPoE connection. All thats left now is to save my WinAMP EQF settings and import them, and I'll be up n' running on all cylinders..!

[Listening to Eric Clapton - Bell Bottom Blues]

Controller

2005-07-12T05:55:00.000-07:00

I found the best RAID page yet. I'm back to RAID for my new project which involves automating tests somehow, for Controller Firmware. I also have to study CM Synergy, a Config Mgmt tool.

ssh -n

2005-07-06T02:46:00.000-07:00

After y'day's fiasco, today was a rewarding day. I made a test framework in April (just a month :-), tho' testing n' debugging took another month, 'cuz there were 100+ bugs. Its been two months since then.. n' y'day I was called to deploy it in the biggest project ($1m) in the RnD services part of my company. Its working perfectly, i.e. ZERO bugs!

I encountered a major problem tho', 'cuz SSH commands were causing the shellscript (thats what the framework is, a 700-line one at that!!) to exit! I broke my head for 24 hours since then till now, to discover the '-n' switch! Only the Solaris rsh page told me what "avoids unfortunate interactions between rsh and the shell which invokes it". I tried it for ssh and thankfully, it worked!!

Python

2005-06-29T21:33:00.000-07:00

I've started learning Python.. looks good. There's a nice guide here.

FAST

2005-04-19T05:58:00.000-07:00

That stands for Framework to Automate SNKutty's Tests. I just finished its BASH shell script implementation and will soon be putting up the code. I found a good page here on how to configure SSH.. which I needed to do to capture server log files. I'll be posting links to more resources soon..

Update:
FAST documentation
FAST code (tar xvf fast.doc)

To convert Excel-copy-textfile-pasted stuff to configuration file format, run this script on it:

#!/bin/bash
while read line
do
if [[ $line == TC_UC* ]]
then
num=1
ucid=$line
ufil="${ucid}_Test.cfg"
elif [[ x$line != x ]]
then
if [ ! -e $ufil ]
then
echo "Default_Verify_String=" >> $ufil
echo "[Default_Cleanup]" >> $ufil
echo "[@Default_Cleanup]" >> $ufil
fi # End of if file doesn't exist
echo "TCID@${ucid}_${num}" >> $ufil
echo "[Test_Body]" >> $ufil
echo "$line" >> $ufil
echo "VERIFY@" >> $ufil
echo "[@Test_Body]" >> $ufil
echo " " >> $ufil
let "num+=1"
fi # End of line identify process
done<$1

BASH

2005-03-22T00:36:00.000-08:00

After Expect, its now time for me to learn Bash [Bourne-Again Shell] n' shellscripting.. I found this excellent guide which I'm looking through. As I'm sure you all know, bash is the command prompt or shell that is mainly used by Linux, so its really the most essential thing for someone who's going to work on such UNIX-like OSes..

Expect

2005-03-18T00:30:00.000-08:00

Its been a long time. I'm in a new project again, where I've to automate interactive applications as part of testing. I'm consulting my ex-PM (an outside resource) to work and he suggested Expect as a solution. Its done for the US Govt., viz. NIST by this dude. To start off, I found this really helpful tutorial, with which I wrote my first Expect script. Besides, I found a good index at another resource on the Cotse site.. I'll keep this updated.

Makefile

2005-02-02T00:35:00.000-08:00

Here's what your makefile (with dmalloc support) should look like..
DMALLOC = ../dmalloc-5.4.2

CC = gcc
INCLUDE = ./include
SOURCE = ./src
BIN = ./bin
OBJ = ./object
CFLAGS = -g -Wall -Werror -I$(INCLUDE) -I$(DMALLOC) -DDMALLOC

OBJECTS = file1.o file2.o ...

vpath %.h $(INCLUDE)
vpath %.c $(SOURCE)

binary: $(OBJECTS)
$(CC) -o $(BIN)/binary $(OBJECTS) ${DMALLOC}/libdmalloc.a
mv *.o $(OBJ)

$(OBJECTS): common.h

file1.o: file1.h
file2.o : file2.h
main.o : main.h

clean :
rm -f $(BIN)/binary
rm -f $(OBJ)/*.o

Scripting and dmalloc

2005-02-01T20:58:00.000-08:00

You've to save it and make it executable: chmod 775 modreg.tcl
I wrote an ordinary shellscript too.. start off with #!/bin/sh or wherever sh exists. Running it with sh filename also works, just like tcl filename will..

I also learnt how to test for memory leaks with dmalloc. All you need is a folder dmalloc containing the program. Then..

dmalloc-5.4.2]$ sh ./configure
dmalloc-5.4.2]$ make (make threadssl and make shlib)
dmalloc-5.4.2]$ cd ../Feb1/
Feb 1]$ alias dmalloc=../dmalloc-5.4.2/dmalloc
Feb 1]$ export DMALLOC_OPTIONS=log-stats,log-non-free,log-trans,log=logfile,inter=1
Feb 1]$ dmalloc

The output should contain the line:
Logpath 'logfile'

Feb 1]$ make -f Makefile.dmalloc
Feb 1]$ ./bin/binary

I'll supply details of the dmalloc Makefile shortly..

TCL

2005-02-01T20:49:00.000-08:00

I've been looking up a lot of TCL lately. Wrote my first script. Its for modreg.tcl, which modifies a field within a register without disturbing surrounding bits. Assume commands readreg (which reads the contents of a register, specified by its hexadecimal address in memory) and writereg (which writes a value to a register).

#!/usr/bin/tclsh
#
# Usage : modreg.tcl reg value low high
#
# Example : modreg.tcl 0x340 0x11 3 7
#
# Now, this would read register 0x340, write the value 0x11 into
# bits 3 through 7 and write this back into register 0x340.
#

# Power procedure
proc power {base p} {
set res 1
while {$p>0} {
set res [expr $res*$base]
set p [expr $p-1]
}
return $res
}

# Check arguments
if {$argc != 4} {
puts "Invalid arguments!"
return 0
}

# Read arguments into variables
set reg [lindex $argv 0]
set new [lindex $argv 1]
set low [lindex $argv 2]
set high [lindex $argv 3]

# Swap low and high if user entered them backwards
if {$low > $high} {
set temp $low
set low $high
set high $temp
}

# Process high
set high [expr $high+1]

# Read register value into 'val' with the 'readreg' command
set val [exec readreg $reg]

# Process variables 'highp' and 'lowp' from low bits and high bits
set highp [expr {[power 2 $high]-1}]

if {$low == 0} {
set lowp 0
} else {
set lowp [expr {[power 2 $low]-1}]
}

# Find number to AND with 'val' to clear the appropriate bits
set and [expr {0xffffffff - $highp + $lowp}]

# Clear the appropriate bits
set clear [expr {$val & $and}]

# Left-shift the value to be written to the field by appropriate amount
set or [expr {$new << $low}]

# Find result by ORing this with 'clear'
set result [expr {$clear | $or}]

# Write this result into the register with the 'writereg' command
set ret [exec writereg $reg $result]

grub: update

2005-01-16T22:53:00.000-08:00

Darn, I just found this page which possibly has a fix to the problem mentioned below! Omigosh, what would people do without the Internet?! Format the C drive and re-install Windows probably!! Just like the dunce did on my home PC :`-(

grub: WinXP/FC3 combo problems

2005-01-16T22:49:00.000-08:00

A major problem cropped up on the PC at home.
Grub stopped booting WinXP, saying:

rootnoverify (hd0,0)
chainloader +1
Error 13: Invalid or unsupported executable format

They got a technician, who knew zilch about Linux. He tried repairing WinXP, which I knew wouldn't work. Finally, he had to format C drive and re-install Windows, overwriting the MBR n' removing access to FC3.

My advice: If you're installing Fedora on a system which already has Redhat, do NOT upgrade grub- leave it as it is..

strtod

2005-01-11T03:05:00.000-08:00

Funny.. strtod doesn't support hexadecimal in FreeBSD. Use this instead:

/*************************************************************************
* NAME:              strtodec
* SUMMARY:      Converts string to decimal number
* RETURNS:      Returns the decimal number.
* AUTHOR:         Sankar N.
************************************************************************/
int strtodec (const CHAR8 *src) {
   /* Integer to hold resulting value */
   int dec;

   /* Check if the string contains a hexadecimal number */
   if ( ('0' == *(src)) && ( ('x' == *(src+1)) || ('X' == *(src+1)) ) ) {
      sscanf (src, "%x", &dec);
   } else {
      /* String contains decimal number */
      sscanf (src, "%d", &dec);
   }
   return (dec);
}

smp

2005-01-11T02:58:00.000-08:00

I read that a Linux kernel suffix of smp implies a multi-processor system. Funny.. FC3 installed 2.6.9-1.667smp on my Intel P4 @ 2.8GHz (with HT)..

(Listening to Temple of the dog - Say hello to heaven...)

automount

2005-01-10T03:26:00.000-08:00

Have been battling with /etc/fstab to automount the ntfs partitions at startup and make them accessible to ordinary users. Almost had to admit defeat, when I came across the key.

/dev/hda1 /mnt/C ntfs ro,user,umask=0222 0 0
/dev/hda5 /mnt/F ntfs ro,user,umask=0222 0 0

(Listening to Collective Soul - The world I know...)

Music

2005-01-07T01:02:00.000-08:00

I was stunned when XMMS didn't play MP3, popping up some message about copyright/patent issues. Well, I found the solution by doing an rpm search for xmms-mpg123. The XMMS site showed me where to get winamp equalizer presets. Useful!

(Listening to Eric Clapton - My Father's Eyes...)

FC3

2005-01-06T23:30:00.000-08:00

I was home last week. I didn't have Linux, so I thought I'd install it. The ISO images were there at the Fedora site.. for 3 CD's! My connection doesn't let me download that much, so I went to a shop and found just what I wanted! LFY were giving a Fedora Core 3 DVD with their mag! Everything worked fine- sound, cable modem, etc. all detected..

What's more, my dream came true.. It packaged Ximian Connector (MS Exchange support) with Evolution. Back at work, I had to check it out pronto, so with the CDs, I installed it over Redhat and got the usual problem with the sound card, resolved from the ALSA site.

Next, the mount: ntfs not supported by kernel. I followed instructions and downloaded the rpm from the Linux-NTFS site. Now thats working too! :)
Put the icing on the cake by configuring the drives to automount by editing the /etc/fstab file. Ready to rock n' roll!!

Man Page

2004-12-27T23:55:00.000-08:00

I'm back after a long hiatus.. have been very busy with the new project. A tool has been developed by Santosh, the guy who's mantle I've donned in this project, called Randomizer. Additional requirements keep coming from the client, so my role is to change/add to the tool to support these. One of them was a man page, which I made today. I'd like to show you how you to do it and killing two birds with one stone too, 'cuz it explains what the tool does! :)

\" Process this file with groff -man -Tascii rand.txt
\" Thank goodness for the Linux Man-Page Mini-HOWTO.
\" And for man 7 man.
\" This is my first attempt at writing a man page. Bear with me.
\"
\" Note: This is for version 1 of the randomizer.
.TH RANDOMIZER l 2004-12-28 Linux "User Manuals"
.SH NAME
randomizer \- A tool to produce random values for variables supplied.
.SH SYNOPSIS
.B randomizer -file
.I FILENAME
.B [-prefix string] [-ignore varlist] [-change] [-verbose] [-strict]
.B [-scriptfile
.I FILENAME
.B ] [-assertmode]
.SH DESCRIPTION
.B Randomizer
takes in a rules file and optional switches to control output. The rules file
has variables and rules describing the relationships between them.

.B Randomizer
produces random values for these variables as output, such that the rules
governing the relationships between those variables are not, any of them,
violated. If run for long enough, Randomizer would eventually produce all
possible legal combinations for the given input variable sets.

.B Randomizer
assigns a value of -1 to the concerned variable on encountering invalid
rules. Errors are printed to stderr and other output to stdout.
.SH RETURN VALUE
.nf
0 - on successful completion
1 - on encountering error(s)
.fi
.SH OPTIONS
.IP "-file FILENAME"
Specify the rules file for randomizer
.IP "-prefix string"
Specify string to be prefixed for each o/p
.IP "-ignore var1, var,..."
Ignore variables var1, var2,... during o/p
.IP -change
Print only variables that undergo a change
.IP -verbose
Enable debug level messages at runtime
.IP -strict
Compel all variables to be declared with initialisations
.IP "-scriptfile FILENAME"
Specify the scriptfile for variable replacement
.IP -assertmode
Treat randomization rules as assertions
.SH USAGE
A variable must lie in the range (0, 2147483647) to be valid.

The inits file must contain variable initialisations, in the format:
.B variable = value
where the variable name must start with an alphabet or underscore.

The rules file must contain relationships between operands. Operands are
either variables or constants. Rules must adhere to the format:
.B variable ; expression (&&/||) expression (&&/||) expression...

Expressions are to be defined in the format:
.B operand operator operand
, using the operators
.B <=, <, >=, >, !=, ==
and their combination with the ternary operator ?:, which is used as
.B a ? b : c
(if a, then b, else c)

.P Multi-line rules should be enclosed in curly braces.
The rules file may contain comments, beginning with a hash (#) symbol.
.SH AUTHORS
.nf
Santosh B. Kulkarni
Sankar Narayanankutty
.fi

Found direction

2004-10-19T04:54:00.000-07:00

Now I know how crucial it is, not to lose sight of the goal.. I forgot the whole reason why we're trying to get dm to work with RAID devices .. 'cuz with md, you can't take a snapshot!!! I I just went to talk to Manu, to tell him I wuz stuck.. n' was reminded of this!!

MD

2004-10-11T00:39:00.003-07:00

I've been reading through some storage-related websites. At my interview, I remember claiming to know a bit about computer hardware. The interviewer proceeded to ask me what I knew about ways of connecting a hard drive and I talked about IDE and SCSI, and tho' I didn't even know what they stood for, I remarked that the latter was better. I shot in the dark with an insane mumbling of 'Integrated Development Environment', but immediately realised my mistake and admitted it. Today, I came across a couple of good pages on SCSI vs. IDE.

I've also been browsing through a lot of MD code (MD is an EVMS plugin) lately. Manu came over today n' we cracked our heads trying to find out the flow from the Engine, through the InternalAPI, to the setting up of the plugins by loading them as modules. My current task is to understand how the MDRegMgr decides what to call.. linear, raid0, raid1, raid5 or multipath... Update: It doesn't. You have to call MDRaid1RegMgr for eg.

I'm back !!

2004-10-05T03:55:00.000-07:00

The top-secret thingy is almost scrapped. So' I'm back to the Linux Snapshot Driver project! Yippee!! :D

Reading code again to try n' find out where EVMS uses MD for RAID1. My task is to get DM to do this instead.. My "walking through the code" has taken me a few steps ahead. Discovered Dm.c n' Devmapper.h which talk about stuff I need to know. On an impulse, I searched for Md n' Voila! Hit upon Md.h.. I coulda kicked myself for not finding this stuff earlier!

Also found a perl module MD.pm, which I'm trying to decipher..

Boohoo!

2004-09-27T08:43:00.000-07:00

Today, I thought, "Why do I use Windows?" n' pat came the answer, "Outlook!". Yes, the only real reason I select DOS in GRUB each time is 'cuz checking mail n' the calendar wuz never easier than with Outlook. OK, I did get Evolution to behave really well, but what if IS (Information Systems) decide one day, to take away the exclusive SMTP/POP access that I enjoy here? How did this happen?

Well.. I went home once last year n' tried to configure Outlook Express to work. It didn't. I got back n' raised a complaint that my SMTP/POP didn't work. I think someone enabled just my username! That wuz that n' it even helped me in my previous project where I had to configure Winfax' internal mail client to work. Predictably, it worked only with my login, n' not even with my PM's! :p

OK, so if IS suddenly discover the undeserved privilege that I've been accorded, they might just strip me of access. I will then have to fall back on the MS Exchange 2000 access that everyone else has. Why not get it to work in Linux? 'cuz therez only Ximian Connector that will support it.

I fought with obstinate wget to get Red Carpet installed, to no avail. But perseverance paid off today, when I found the Novell location where I could download Connector without red-carpet! I did it n' discovered that it required a newer version of Evolution. Well, I found that there too..!!

But it asked for this package and that.. n' I gave up trying to download dependencies. I then hit upon GARNOME which is currently taking care of all my troubles. I hope everything's OK when I get back tomorrow..

Update: It wasn't. GARNOME also did its part of the asking- it wanted libbz2..

ProjDemise

2004-09-23T02:09:00.000-07:00

Tho' I shall try to the utmost to keep it alive, Linux stuff will henceforth cease.. 'cuz I got assigned a new testing project, where we have to try n' automate testing. For this, we looked at STAF, which is available for Windows too. STAF works with Perl. So I'm trying to learn some Perl. I came across this excellent tutorial, which I'm going through now..

Hard drive

2004-09-21T07:29:00.000-07:00

With that BAD fs [filesystem] report, I wonder if my hard drive will conk off?! I guess I should take an image of C: sometime. Cool.. if what I'm working on is developed, one would be able to take a snapshot of Linux as well! Herez some interesting stuff Manu told me, which I didn't know earlier.

The hard drive has an MBR, which has the location of the OS on the Primary Partition. From what I understood, when you install Linux on a computer running Windows, this location is overwritten with that of GRUB (the multi-boot boot loader). At the same time, GRUB records the location of the Windows OS loader. So, when you switch on the computer, the first thing that comes up is GRUB. It lets you choose between booting Linux or Windows. Neat, huh?

I came across this lovely page on RAID.
EVMS interfaces to the disk through two interfaces:
1) DM, i.e. Device Mapper (regular, striped n' RAID0 disks), and
2) MD, i.e. Multiple Device (used for RAID0/1/4/5 n' linear devices)

I've to trace the code from /usr/src/evms-2.3.4/ui/cli/evms.c (Command-Line Interface) to find out how the engine (/usr/src/evms-2.3.4/engine/) uses dm and md. Great Scott!

Me trying to read evms code
On how to create an inode
I'm browsing with Source Insight
But C's putting up a valiant fight
Guess I'll soon have to hit the road

Its working!

2004-09-21T03:21:00.000-07:00

Finally got EVMS working y'day. I connected a Fujitsu 4 GB hard disk to play around with. I managed to do a %: fdisk hdb and get away with it :D

After the 'd' and 'w' commands, it did pop up the same thing about the new partition table and kernel adopting the old table till reboot. I almost burst into tears, but decided to reboot n' check to see if it really wuz screwed. Thanked my stars when GRUB loaded and the kernel came up OK..

Once in a while, the computer still craps about the filesystem when I start it, and obstinately forces a check. PartitionMagic still calls Disk1's partition type 'BAD' and probably wants it spanked :p

Here's how to create a snapshot with EVMS. After you install it, do a
%: ldconfig or else you'll be scolded for missing a library!
[Thank God it doesn't ask you to replace all the books :| OK sorry!]

%: evms_activate
%: evms

EVMS : create:segment,hdb_freespace1,size=100MB
(You could open %: evmsgui and click the small +'s to find out which /dev/hd has enough freespace..)
This will return a handle (the hd created). Lets assume its hdb1.

EVMS : create:container,LvmRegMgr={name="container",pe_size=16MB},hdb1
EVMS : create:region,LvmRegMgr={name="region",size=100MB},"lvm/container/Freespace"
EVMS : create:object,Snapshot={original="/dev/evms/hda1",snapshot=snap},"lvm/container/region"
EVMS : create:volume,snap,n="volume"

(Here, /dev/evms/hda1 is the drive you want to take a snapshot of.)

Tip: If you want your Windows partition mounted when you start Linux, herez the line you could add in your /etc/fstab file.

/dev/hda1 /mnt/C auto auto,users,ro 0 0

Replace the first parameter with your Windows drive and the second with the directory where you want it mounted. n' btw there's a Explore2FS utility, which lets you view your Linux partitions in Windows :)

Firefox

2004-09-17T08:21:00.000-07:00

Hooboy! I'm finally up and running! WITH NTFS support..

Here's something I wanna tell ya about. Mozilla's Preview Release 1.0 of Firefox. If you're using Linux and was cribbing like me that you couldn't get any blog stuff to work, go and get it before you do anything else!!

The blogger 'insert link' button works properly unlike in Mozilla. I heard first about Firefox from a post on nidrajiva's blog and decided to try it out after reading Ashik's comment about a blogger plugin. Well folks, it does exist! Neat job, complete with the all-important OPML import/export too! n' if you are an Opera fan just for mouse gestures, here's an extension for that! ;)

More plugins exist, but this thoughtful Gmail Notifier is special indeed!

Why?!

2004-09-17T04:46:00.000-07:00

Oh Why?! Did it happen to me?! I remember selecting Keep old partitions and use free space, when I installed Redhat. Well, I checked %: /dev and found a coupla extra hdxs. Mounted them n' discovered that my old linux partitions were intact. Retrieved all my downloads into my current partition. n' wonder of wonders! I could also mount my NTFS partitions in 2.4.26!

Well.. but I found out that the new installation had used up all the 7 GB I'd freed from my Windows partitions using Disk Management (Right-click My Computer, select Manage and navigate in Computer Management). I approached Manu n' he told me the higher numbers were the newly created partitions n' so I could delete the old linux / and swap partitions to free up space. I launched %: fdisk. Note that hitting 'p' and 'd' to your heart's content doesn't affect anything permanently, until you deliver the final death-blow 'w', which writes the table to partition and exits. Well, all was well until it popped up a scary message saying the new table is unacceptable and that the kernel would use the old table till reboot.

I typed in reboot n' waited. The computer presented me with.. GRUB in text! A grub> prompt waited for me to respond. I gazed stupidly at the screen, thoughts tumbling one over the other. The prospect of Windows being wiped out struck me full n' hard in the face. I got up groggily n' tottered over to Manu's desk. Breathlessly, I told him what happened.. He sauntered over n' casually asked me to insert the Redhat Installation CD. The bash prompt came up n' he entered that dreadful command: %: fdisk. We watched n' waited. He gingerly pressed 'p' n' it printed the partition table..

Hurrah! My Windows partitions are intact! I thought I'd truly lost both my OS's. I couldn't care less if Linux was wiped out, which it wuz as soon as Manu deleted all the ext partitions.! He restarted the computer n' it brought up the Redhat Install screen without an Upgrade option. I set to the task of reinstalling everything.. again.. This time I made no mistake. Remove all Linux partitions n' Install Redhat.

I'm back to square one. Up n' running.. on 2.4.20-8.
PHEW! TGIF! Have a great weekend!!

eth0

2004-09-17T00:32:00.000-07:00

When I restarted and booted the new kernel, it did not Bring up my eth0 (in my case, an Intel® PRO/1000 Gigabit Ethernet adapter). I discovered you HAVE to support it as a loadable module in the Network Devices section Ethernet (1000 Mbit), when you configure the kernel.

But then, it Failed to obtain IP information. I wonder why only the new kernel presented these problems. Well, running %: neat, which incidentally is the Network Configuration tool, Editing the Device and Statically setting the IP address resolved the problem.

You'd do well to sign up at Experts Exchange!
I'm up and blogging on 2.4.26 now.. :D

Kernel compile

2004-09-16T06:12:00.000-07:00

Make sure you have devfsd installed in your old kernel. This is 'cuz once you build the new kernel, it maps drives assuming you have devfs in your old kernel, n' I didn't!! All thanks to Damaru for helping me with this one!

While you configure the kernel, make sure you enable support for your sound card, ethernet controller n' other devices. You can include them with the kernel, or as loadable modules. In the latter case, you'll find them as .o's in the lib/modules/2.4.26/kernel/drivers/ directory. You can insert them with the /sbin/insmod command. /sbin/lsmod lists your loaded modules. Note that if you've included them with the kernel, they won't be listed! n' do a %: ln -s /linux-2.4.26/ linux to ease things. Ah, but I digress..

Fine! Now you're ready for some serious making out ;)
%: make dep ; make bzImage ; make modules ; make modules_install

You could do a %: make install too, so that your boot loader file (/etc/grub.conf in my case, as I use GRUB) is updated to display your new kernel. Now you type in %: reboot to do the obvious..

Kernel 2.4.26

2004-09-16T05:49:00.000-07:00

I hit an issue when I tried to install D4X. The GLIB [GNU Library probly] needs to be version 2.4.0 or higher. I decided I'd better do all this after getting on with the immediate need of upgrading the 2.4.20-8 kernel which came with the Redhat 9.0 distro, to 2.4.26, so that I can run EVMS.

I need EVMS for my project. n' it needs 2.4.26. The EVMS website gives you ALL the instructions you need to building the new kernel and getting EVMS to work with it. Make sure you get device-mapper.1.00.18, 'cuz EVMS doesn't work well with 1.00.19.

Also, if you're using a multi-boot with Windows like I am, make sure you configure the kernel %: make xconfig to support the appropriate file system (NTFS in my case- Windows 2000) so that you can mount your Windows partitions in Linux. The %:mount /dev/hdXX /mnt/C -t ntfs worked perfectly in 2.4.20-8. However, I couldn't get it to work in 2.4.26. You might need to download the latest Linux-NTFS driver.

/usr/bin

2004-09-16T04:47:00.000-07:00

I did something ingenious about an hour ago. I was removing opera from my system in order to install Mozilla's new pre-release version 1.0 of Firefox. Well.. did a few %: locate operas to find out the folders and wuz merrily doing %:rm -Rf directory_name when I did it on /usr/bin. :`-(

Trust me. Do NOT try this at home.. or in the office.. or anywhere else for that matter! :( Ah well! Looking on the bright side of things, I can at least relive my experience from scratch on this blog :) I'm up n' running now with just evolution in my %:ls /home/sankarnk output!

Lynx

2004-09-15T23:21:00.000-07:00

I used to browse the web when I was in 10th std. with my shell internet account. It was my first experience with UNIX, 'cuz my ISP (VSNL) ran a UNIX host which I connected to (using HyperTerminal) thru' dial-up. My account allowed 500 hours of access for Rs.5k per year. The TCP/IP equivalent cost thrice as much. I used Lynx, a text browser.

Here are some Links. Thanx to Vin's comments, I had a discussion with Kishore on RAM. I found this nice Memory Primer on the net. However, for knowledge on hardware in general, I recommend howstuffworks. Today on the Computer Channel, Vinu's needs have strangely been catered to by a page on How BIOS Works.

Download

2004-09-14T05:19:00.000-07:00

D4X is one app I can't live without! OpenOffice.org is another thing that falls in the same category. When you want software that can do a particular task, you'd do well to look for it on the universal resource for a LOT of projects, viz. SourceForge.Net.

Some useful stuff:
1) Gaim n' aMSN - IM apps [I need to make a glossary!]
2) RSSOwl - RSS|ATOM news feed reader (aggregator)
3) NTFS driver - to access your Win2K partitions.

dev

2004-09-14T04:58:00.000-07:00

As a developer, you need a tool to browse source code. For my first testing project in avionics, I used Source Insight. Manu just came over to tell me it is in fact, the best tool. Unfortunately its for Windows. Since this is a Linux blog, you should instead, read about Cscope, developed by Bell Labs and an official part of the AT&T UNIX distro. ViM is built in with Cscope support, so I'm all excited! Read about it!

Install

2004-09-14T00:40:00.000-07:00

My favorite editor is ViM. Incidentally, I love it so much, I use it the Windows version of it too.. Once you get used to it, everything else, including Notepad, is trash! Btw, here's a lovely page I came across on chmod.
The equivalent of Windows Explorer in Redhat is a graphical shell called Nautilus (for Gnome). You can access network drives from Nautilus by typing in smb://network_folder in the Location region.

Herez how you install a package. "%" is your shell prompt:

If you have the RPM:
%: rpm -i filename.rpm

If you have the tarball, unzip it:
%: tar xvzf filename.tar.gz
OR
%: tar xvjf filename.tar.bz2

Become root:
%: su

Usually, you've to type in this:
%: ./configure
%: make
%: make install

You could also type in:
%: ./configure ; make ; make install

n' go for a coffee break! ;)

MyConfig

2004-09-13T23:09:00.000-07:00

OK, first things first.. here's my configuration:

A Dell OptiPlex GX270 running Redhat 9.0 (Shrike) [Kernel 2.4.20-8]

Why did I put this up? So that people who search Google for problems on this config. are benefitted by solutions published on this blog.

Now that that's over with, lets proceed..

What did I do first? The display was behaving queer. I found out it wuz 'cuz only 1MB RAM wuz being reported by the motherboard. Changing it to 8MB in the BIOS didn't help. So I flashed the BIOS with a previous revision, viz. A02 and it started working fine. But the sound still didn't work. Well, I got the ALSA driver from their site- version 1.0.2a, but there wuz no RPM, so I just did 'make'. Previously it wouldn't detect anything, but then it detected the AC'97 on Intel board, but still /dev/mixer couldn't be written to.

But then I got it working! Next, I configured Samba Server to run successfully on my comp. Then, I discovered Ximian Connector an Email client for Linux, which actually has MS Exchange support! Novell has now made it free! I haven't been able to get it working yet and am still on Ximian Evolution, using SMTP/POP3.

More later..

Why SANLinux?

2004-09-08T22:30:00.000-07:00

SANLinux can be interpreted in three ways:

1) SAN [Storage Area Networks] Linux
2) SAN[kar's] Linux
3) Linux-san [Mr. Linux]

Pretty weak, eh?
Well, thats how this site will go forth..