Back to college and my friends

“From monday we go to the college back,

  Noone in our group is horse,queen and jack

  There is ng,ini,mahe,deepak and kannan

   And also his notorious “annan”

   All of us always put in a pack  “ 

————- my very own

Faith

“Faith is to believe what we do not see and the reward of faith is to see what we believe ….. “

———–    Swami Vivekananda

The Apache Web Server

HISTORY: 

The Apache HTTP Server, commonly referred to simply as Apache, is a web server notable for playing a key role in the initial growth of the World Wide Web. Apache was the first viable alternative to the Netscape Communications Corporation web server (currently known as Sun Java System Web Server), and has since evolved to rival other Unix-based web servers in terms of functionality and performance. Since April 1996 Apache has been the most popular HTTP server on the World Wide Web

Apache is primarily used to serve both static content and dynamic Web pages on the World Wide Web. Many web applications are designed expecting the environment and features that Apache provides.

Apache is the web server component of the popular LAMP web server application stack, alongside MySQL, and the PHP/Perl/Python programming languages.

Apache is redistributed as part of various proprietary software packages including the Oracle Database or the IBM WebSphere application server. Mac OS X integrates Apache as its built-in web server and as support for its WebObjects application server. It is also supported in some way by Borland in the Kylix and Delphi development tools. Apache is included with Novell NetWare 6.5, where it is the default web server.

License :

The Free Software Foundation does not consider the Apache License to be compatible with version 2 of the GNU General Public License (GPL) in that software licensed under the Apache License cannot be integrated with software that is distributed under the GPL:

This is a free software license but it is incompatible with the GPL. The Apache Software License is incompatible with the GPL because it has a specific requirement that is not in the GPL: it has certain patent termination cases that the GPL does not require. We don’t think those patent termination cases are inherently a bad idea, but nonetheless they are incompatible with the GNU GPL.

Symbian — The mobile OS

Design:

Symbian OS, with its roots in Psion Software’s EPOC, is structured like many desktop operating systems with pre-emptive multitasking, multithreading, and memory protection.

Symbian OS’s major advantage is the fact that it was built for handheld devices, with limited resources, that may be running for months or years. There is a strong emphasis on conserving memory, using Symbian-specific programming idioms such as descriptors and a cleanup stack. Together with other techniques, these keep memory usage low and memory leaks rare. There are similar techniques for conserving disk space (though the disks on Symbian devices are usually flash memory). Furthermore, all Symbian OS programming is event-based, and the CPU is switched off when applications are not directly dealing with an event. This is achieved through a programming idiom called active objects. Correct use of these techniques helps ensure longer battery life.

OWNERSHIP: 

Symbian is currently owned by Nokia (47.9%), Ericsson (15.6%), Sony Ericsson (13.1%), Panasonic (10.5%), Siemens AG (8.4%) and Samsung (4.5% )

The following Open Source software has been rewritten for Symbian 9.1:

Utilities
PuTTY, a telnet/ssh client
Internet Radio
SymTorrent, a bittorrent client

Symella, a gnutella client
Python interpreter
Apache HTTP Server, a web server

Game emulation
ScummVM

Multimedia
OggPlay – Audio player with ogg vorbis audio format support

Symbian has announced PIPS (PIPS Is POSIX on Symbian) which may increase the number of Open Source projects written for Symbian 9.1.

cooooool…………….more open source on mobiles

Default values of a partially initialised struct

Consider the code,

#include<stdio.h>
main()
{
struct a
{
int b;
float c;
char d;
};

struct a a1 = {10};
printf(“%f\t%d”,a1.c,a1.d);
}

OUTPUT:

0.000000 0

EXPLANATION:

The default values for c and d are the above.’d’ is  printed as an integer and hence returns 0 and no o/p is obtained when we print is as a char

NOTE:

The same is true for partially initialised arrays

int a[3] = {10}

printf(“%d%d”,a[1],a[2])

returns 0 0 obviously

Return type for printf

The printf() returns the number of characters sent to the standard output device……

<code>

#include<stdio.h>
main()
{
int i;
int a = 10;
printf(“%d”,a);
printf(“%d”,printf(“%d%d%d”,a,a,a));
}

</code>

OUTPUT:

10 10 10 6

EXPLANATION :

The inner printf function gets executed first and prints 10 10 10.Then the outer function is executed which returns 6 because of the 3 10s that are printed which is equal to 6 characters

 

Hurd – The real GNU OS

Introduction to the Hurd:

The GNU Hurd is the GNU project’s replacement for the Unix kernel. The Hurd is a collection of servers that run on the Mach microkernel to implement file systems, network protocols, file access control, and other features that are implemented by the Unix kernel or similar kernels (such as Linux).

Currently, the Hurd runs on IA32 machines. The Hurd should, and probably will, be ported to other hardware architectures or other microkernels in the future.
The Hurd interfaces are designed to allow transparent network clusters (collectives), although this feature has not yet been implemented.

The Hurd is an attractive platform for learning how to become a kernel hacker or for implementing new ideas in kernel technology. Every part of the system is designed to be modified and extended.

It is possible to develop and test new Hurd kernel components without rebooting the machine (not even accidentally). Running your own kernel components doesn’t interfere with other users, and so no special system privileges are required. The mechanism for kernel extensions is secure by design: it is impossible to impose your changes upon other users unless they authorize them or you are the system administrator.

The Hurd is real software that works Right Now. It is not a research project or a proposal. You don’t have to wait at all before you can start using and developing it.

`Hurd’ stands for `Hird of Unix-Replacing Daemons’. And, then, `Hird’ stands for `Hurd of Interfaces Representing Depth’. We have here, to my knowledge, the first software to be named by a pair of mutually recursive acronyms. 

Status of the project

The Hurd, together with the GNU Mach microkernel, the GNU C Library and the other GNU and non-GNU programs in the GNU system, provide a rather complete and usable operating system today. It is not ready for production use, as there are still many bugs and missing features. However, it should be a good base for further development and non-critical application usage.

The GNU system (also called GNU/Hurd) is completely self-contained (you can compile all parts of it using GNU itself). You can run several instances of the Hurd in parallel, and debug even critical servers in one Hurd instance with gdb running on another Hurd instance. You can run the X window system, applications that use it, and advanced server applications like the Apache webserver.

On the negative side, the support for character devices (like sound cards) and other hardware is mostly missing. Although the POSIX interface is provided, some additional interfaces like POSIX shared memory or semaphores are still under development.

All this applies to the current development version, and not to the last release (0.2). We encourage everybody who is interested to try out the latest development version, and send feedback to the Hurd developers.

Crontab

Crontab (cron table)

Schedule a command to run at a later time
SYNTAX
crontab [ -u user ] file
crontab [ -u user ] { -l | -r | -e }

Key
-l List – display the current crontab entries.

-r Remove the current crontab.

-e Edit the current crontab using the editor specified by the
VISUAL or EDITOR environment variables.
After you exit from the editor, the modified crontab will be installed automatically.

Crontab is the program used to install, deinstall or list the tables used to drive the cron daemon in Vixie Cron.
Each user can have their own crontab, and though these are files in /var, they are not intended to be edited directly.

If the -u option is given, it specifies the name of the user whose crontab is to be tweaked. If this option is not given, crontab examines “your” crontab, i.e., the crontab of the person executing the command. Note that su can confuse crontab and that if you are running inside of su you should always use the -u option for safety’s sake.

cron file is used to install a new crontab from some named file or standard input if the pseudo-filename `-’ is given.

Each line in the cron table follows the following format: 7 fields left to right Field Meaning
1 Minute (0-59)
2 Hour (2-24)
3 Day of month (1-31)
4 Month (1-12, Jan, Feb, …)
5 Day of week (0-6) 0=Sunday, 1=Monday …
or Sun, Mon, Tue, Wed, Thur, Fri
6 User that the command will run as
7 Command to execute

There are several ways of specifying multiple values in a field:

• The comma (‘,’) operator specifies a list of values, for example: “1,3,4,7,8″
• The dash (‘-’) operator specifies a range of values, for example: “1-6″, which is equivalent to “1,2,3,4,5,6″
• The asterisk (‘*’) operator specifies all possible values for a field. e.g. every hour or every day.

There is also an operator which some extended versions of cron support, the slash (‘/’) operator, which can be used to skip a given number of values. For example, “*/3″ in the hour time field is equivalent to “0,3,6,9,12,15,18,21″; “*” specifies ‘every hour’ but the “/3″ means that only the first, fourth, seventh…and such values given by “*” are used.

Cron will email to the user all output of the commands it runs, to silence this, redirect the output to a log file or to /dev/null

Example

Run /usr/bin/somecommand at 12.59 every day and supress the output (redirect to null)

59 12 * * * simon /usr/bin/somecommand >> /dev/null 2>&1

Permissions
If the allow file exists, then you must be listed therein in order to be allowed to use this command. If the allow file does not exist but the deny file does exist, then you must not be listed in the deny file in order to use this command. If neither of these files exists, then depending on site-dependent configuration parameters, only the super user will be allowed to use this command, or all users will be able to use this command.

Rules and first one

Hi folks,i’ll be discussing a special type of poems in this section called the “limericks”….The rule or pattern for these poems are:

Limericks consist of five anapaestic lines.
Lines 1, 2, and 5 of Limericks have seven to ten syllables and rhyme with one another.
Lines 3 and 4 of Limericks have five to seven syllables and also rhyme with each other.
THE FIRST ONE:

Progress Not Apparent?

When the world seems determined to trample
The goals you have set, take example.
The tortoise gets there
Well ahead of the hare
And his steadiness makes the time ample.

Declarations and Definitions

Hi folks,

Here is a little thing I read…The exact difference between a C declaration and a definition.

The term declaration means (in C) that you are telling the compiler about type, size and in case of function declaration, type and size of its parameters of any variable, or user defined type or function in your program. _No_ space is reserved in memory for any variable in case of declaration. However compiler knows how much space to reserve in case a variable of this type is created.

for example, following are all declarations: extern int a; struct _tagExample { int a; int b; }; int myFunc (int a, int b);

Definition on the other hand means that in additions to all the things that declaration does, space is also reserved in memory. You can say “DEFINITION = DECLARATION + SPACE RESERVATION” following are examples of definition: int a; int b = 0; int myFunc (int a, int b) { return a + b; } struct _tagExample example;
Note that extern int a; is a declaration and not a definition because the memory to be allocated for an extern variable is unknown..