Reading and Writing a pointer of continously memory to the file in C

int _backItUp(){
FILE * hFile;
//************************
char *_fileName;
_fileName = getenv("USER");
char buffer[200];
struct timeval tv;
time_t curtime;
gettimeofday(&tv, NULL);
curtime=tv.tv_sec;
strftime(buffer,30,"%Y%m%d_%H%M",localtime(&curtime));
//"%m-%d-%Y %T"
strcat(_fileName,"_");
strcat(_fileName,buffer);
strcat(_fileName,".bak");
//*******************************
hFile = fopen( _fileName, "w");
if (hFile == NULL){
// Error, file not found
printf("*** Failed to open the file ***\n");
return FAILED;
}//end of if
else{
// Process & close file
int nWritten = fwrite(allocatedMem, sizeof(unsigned char), (200*sizeof(SmsDB))+((75)*sizeof(unsigned char))+((200*3)*sizeof(dBlock)), hFile);
printf("*** Taking backup ***\n");
fclose(hFile);
}//end of else
return SUCCESS;
}//end of backItUp()

int _readItUp(){
FILE * hFile;
hFile = fopen( ___fileName, "r");
if (hFile == NULL){
// Error, file not found
printf("*** Failed to open the file ***\n");
return FAILED;
}//end of if
else{
// Process & close file
int nRead = fread(allocatedMem, sizeof(unsigned char), (200*sizeof(SmsDB))+((75)*sizeof(unsigned char))+((200*3)*sizeof(dBlock)), hFile);
fclose(hFile);
}//end of else
return SUCCESS;
}//end of _readItUp()

CTRL+D and CTRL+L signal handling

Code:

#include 

int main()
{
 char c;
 printf("Write: ");
 scanf("%c", &c);
 if(c == 0x0C) printf("ctrl+L was entered\n");
 return 1;
}

but the execution of this doesnt..

Code:

#include 

int main()
{
 char c;
 printf("Write: ");
 scanf("%c", &c);
 if(c == 0x04) printf("ctrl+D was entered\n");
 return 1;
}

ASCII Character Chart with Decimal, Binary and Hexadecimal Conversions

Character Name	Char	Code	Decimal	Binary	Hex
Null	NUL	Ctrl @	0	00000000	00
Start of Heading	SOH	Ctrl A	1	00000001	01
Start of Text	STX	Ctrl B	2	00000010	02
End of Text	ETX	Ctrl C	3	00000011	03
End of Transmit	EOT	Ctrl D	4	00000100	04
Enquiry	ENQ	Ctrl E	5	00000101	05
Acknowledge	ACK	Ctrl F	6	00000110	06
Bell	BEL	Ctrl G	7	00000111	07
Back Space	BS	Ctrl H	8	00001000	08
Horizontal Tab	TAB	Ctrl I	9	00001001	09
Line Feed	LF	Ctrl J	10	00001010	0A
Vertical Tab	VT	Ctrl K	11	00001011	0B
Form Feed	FF	Ctrl L	12	00001100	0C
Carriage Return	CR	Ctrl M	13	00001101	0D
Shift Out	SO	Ctrl N	14	00001110	0E
Shift In	SI	Ctrl O	15	00001111	0F
Data Line Escape	DLE	Ctrl P	16	00010000	10
Device Control 1	DC1	Ctrl Q	17	00010001	11
Device Control 2	DC2	Ctrl R	18	00010010	12
Device Control 3	DC3	Ctrl S	19	00010011	13
Device Control 4	DC4	Ctrl T	20	00010100	14
Negative Acknowledge	NAK	Ctrl U	21	00010101	15
Synchronous Idle	SYN	Ctrl V	22	00010110	16
End of Transmit Block	ETB	Ctrl W	23	00010111	17
Cancel	CAN	Ctrl X	24	00011000	18
End of Medium	EM	Ctrl Y	25	00011001	19
Substitute	SUB	Ctrl Z	26	00011010	1A
Escape	ESC	Ctrl [	27	00011011	1B
File Separator	FS	Ctrl \	28	00011100	1C
Group Separator	GS	Ctrl ]	29	00011101	1D
Record Separator	RS	Ctrl ^	30	00011110	1E
Unit Separator	US	Ctrl _	31	00011111	1F
Space			32	00100000	20
Exclamation Point	!	Shift 1	33	00100001	21
Double Quote	"	Shift ‘	34	00100010	22
Pound/Number Sign	#	Shift 3	35	00100011	23
Dollar Sign	$	Shift 4	36	00100100	24
Percent Sign	%	Shift 5	37	00100101	25
Ampersand	&	Shift 7	38	00100110	26
Single Quote	‘	‘	39	00100111	27
Left Parenthesis	(	Shift 9	40	00101000	28
Right Parenthesis	)	Shift 0	41	00101001	29
Asterisk	*	Shift 8	42	00101010	2A
Plus Sign	+	Shift =	43	00101011	2B
Comma	,	,	44	00101100	2C
Hyphen / Minus Sign	-	-	45	00101101	2D
Period	.	.	46	00101110	2E
Forward Slash	/	/	47	00101111	2F
Zero Digit	0	0	48	00110000	30
One Digit	1	1	49	00110001	31
Two Digit	2	2	50	00110010	32
Three Digit	3	3	51	00110011	33
Four Digit	4	4	52	00110100	34
Five Digit	5	5	53	00110101	35
Six Digit	6	6	54	00110110	36
Seven Digit	7	7	55	00110111	37
Eight Digit	8	8	56	00111000	38
Nine Digit	9	9	57	00111001	39
Colon	:	Shift ;	58	00111010	3A
Semicolon	;	;	59	00111011	3B
Less-Than Sign	<	Shift ,	60	00111100	3C
Equals Sign	=	=	61	00111101	3D
Greater-Than Sign	>	Shift .	62	00111110	3E
Question Mark	?	Shift /	63	00111111	3F
At Sign	@	Shift 2	64	01000000	40
Capital A	A	Shift A	65	01000001	41
Capital B	B	Shift B	66	01000010	42
Capital C	C	Shift C	67	01000011	43
Capital D	D	Shift D	68	01000100	44
Capital E	E	Shift E	69	01000101	45
Capital F	F	Shift F	70	01000110	46
Capital G	G	Shift G	71	01000111	47
Capital H	H	Shift H	72	01001000	48
Capital I	I	Shift I	73	01001001	49
Capital J	J	Shift J	74	01001010	4A
Capital K	K	Shift K	75	01001011	4B
Capital L	L	Shift L	76	01001100	4C
Capital M	M	Shift M	77	01001101	4D
Capital N	N	Shift N	78	01001110	4E
Capital O	O	Shift O	79	01001111	4F
Capital P	P	Shift P	80	01010000	50
Capital Q	Q	Shift Q	81	01010001	51
Capital R	R	Shift R	82	01010010	52
Capital S	S	Shift S	83	01010011	53
Capital T	T	Shift T	84	01010100	54
Capital U	U	Shift U	85	01010101	55
Capital V	V	Shift V	86	01010110	56
Capital W	W	Shift W	87	01010111	57
Capital X	X	Shift X	88	01011000	58
Capital Y	Y	Shift Y	89	01011001	59
Capital Z	Z	Shift Z	90	01011010	5A
Left Bracket	[	[	91	01011011	5B
Backward Slash	\	\	92	01011100	5C
Right Bracket	]	]	93	01011101	5D
Caret	^	Shift 6	94	01011110	5E
Underscore	_	Shift -	95	01011111	5F
Back Quote	`	`	96	01100000	60
Lower-case A	a	A	97	01100001	61
Lower-case B	b	B	98	01100010	62
Lower-case C	c	C	99	01100011	63
Lower-case D	d	D	100	01100100	64
Lower-case E	e	E	101	01100101	65
Lower-case F	f	F	102	01100110	66
Lower-case G	g	G	103	01100111	67
Lower-case H	h	H	104	01101000	68
Lower-case I	I	I	105	01101001	69
Lower-case J	j	J	106	01101010	6A
Lower-case K	k	K	107	01101011	6B
Lower-case L	l	L	108	01101100	6C
Lower-case M	m	M	109	01101101	6D
Lower-case N	n	N	110	01101110	6E
Lower-case O	o	O	111	01101111	6F
Lower-case P	p	P	112	01110000	70
Lower-case Q	q	Q	113	01110001	71
Lower-case R	r	R	114	01110010	72
Lower-case S	s	S	115	01110011	73
Lower-case T	t	T	116	01110100	74
Lower-case U	u	U	117	01110101	75
Lower-case V	v	V	118	01110110	76
Lower-case W	w	W	119	01110111	77
Lower-case X	x	X	120	01111000	78
Lower-case Y	y	Y	121	01111001	79
Lower-case Z	z	Z	122	01111010	7A
Left Brace	{	Shift [	123	01111011	7B
Vertical Bar	|	Shift \	124	01111100	7C
Right Brace	}	Shift ]	125	01111101	7D
Tilde	~	Shift `	126	01111110	7E
Delta	D		127	01111111	7F

Source : http://www.pcguide.com/res/tablesASCII-c.html

Printing char value in binary mode at C programing language

Print a char value(ch variable here) in binary:

printf("%c%c%c%c%c%c%c%c",
     (bitMap[i]&0x80)?'1':'0',
     (bitMap[i]&0x40)?'1':'0',
     (bitMap[i]&0x20)?'1':'0',
       (bitMap[i]&0x10)?'1':'0',
     (bitMap[i]&0x08)?'1':'0',
     (bitMap[i]&0x04)?'1':'0',
     (bitMap[i]&0x02)?'1':'0',
     (bitMap[i]&0x01)?'1':'0');

__________________

VHDL Operators

** exponentiation, numeric ** integer, result numeric
abs absolute value, abs numeric, result numeric
not complement, not logic or boolean, result same

* multiplication, numeric * numeric, result numeric
/ division, numeric / numeric, result numeric
mod modulo, integer mod integer, result integer
rem remainder, integer rem integer, result integer

+ unary plus, + numeric, result numeric
- unary minus, - numeric, result numeric

+ addition, numeric + numeric, result numeric
- subtraction, numeric - numeric, result numeric
& concatenation, array or element & array or element,
result array

sll shift left logical, logical array sll integer, result same
srl shift right logical, logical array srl integer, result same
sla shift left arithmetic, logical array sla integer, result same
sra shift right arithmetic, logical array sra integer, result same
rol rotate left, logical array rol integer, result same
ror rotate right, logical array ror integer, result same

= test for equality, result is boolean
/= test for inequality, result is boolean
< test for less than, result is boolean
<= test for less than or equal, result is boolean
> test for greater than, result is boolean
>= test for greater than or equal, result is boolean

and logical and, logical array or boolean, result is same
or logical or, logical array or boolean, result is same
nand logical complement of and, logical array or boolean, result is same
nor logical complement of or, logical array or boolean, result is same
xor logical exclusive or, logical array or boolean, result is same
xnor logical complement of exclusive or, logical array or boolean, result is same

Source

Keyboard shortcuts for Copy, Cut and Paste

Copy keyboard shortcut : Ctrl + c
Cut keyboard shortcut : Ctrl + x
Paste keyboard shortcut : Ctrl + v
you have to hold Ctrl keyboard and then press the following key ...

Find Your Mac OS X Version

The first step in securing your Mac is to know what OS version is installed. Use the following steps to find your Mac OS X version.

1. From the Apple menu, select About This Mac.
2. The version number will appear in the window.

Source for both picture & text(http://www.cmu.edu)

chmod Recursive permission change (i.e. in the directory and its sub-directories)

If you have a folder with a lot of files and sub-folders inside it and you want to change permission on all the files, then you should run chmod command(changing permission to xxx) with a -R at the end.

chmod -R 777 (folder name)

in case you got the error that you do not have permission, you have to login as root(su command and then password)at Ubuntu run :

sudo chmod -R 777 (folder name)

compiling and installing software from Source Code

Some software is distributed in "Source form". This means you download a file containing all the source code for the application you want to install, unpack it, and compile it on your system. Compiling is the process of turning the source code into an executable binary. The common myth and newbie assumption is that this is very hard todo, or it is only for programmers. Wrong. It is a fairly straight forward process, and you will find that a lot of software you install will need to be built from source.

Typically applications you must compile from source will come as a ".tar.gz", ".tar.bz2", or ".zip" file.

You'll probably want to operate from inside your home directory. If your user is (for example) username, your home directory will be /home/username/. For the rest of this section we will assume you have downloaded your zip file to /home/username/src. If you do not have a src directory, you can create it with the following "mkdir" (make directory) command:

Code:

mkdir /home/username/src/

So, we have our source package in /home/username/src/.

Change to the /home/username/src/ directory with the "cd" (change directory) command like so:

Code:

cd /home/username/src/

Use the "ls" (list directory contents) command, to see the file is present:

Code:

ls

We now need to unzip the zipped file, this is done differently depending on the file extension.

for files ending in .tar.gz, use:

Code:

tar -zxvf 

(replacing with the name of the file).

for files ending in .tar.bz2, use:

Code:

tar -jxvf 

for files ending in .zip, use:

Code:

unzip 

You should now have a new directory, containing all of the source files. To confirm it exists, and to get its name, use the "ls" command again.

Code:

ls

we now need to go into the new directory, so use the cd command:

Code:

cd 

This is where things will differ. Some packages will have an INSTALL or README file which will contain installation instructions. use "ls" to see if the software has an install or readme file. If it does have one, you can use the "more" command to read it, like so:

Code:

more INSTALL

Generally, the final 3 stages are as follows:
- Configure the installation
- Compile the software
- Install the binaries

The pre-installation configuration is done by executing ./configure:

Code:

./configure

This will perform some requirements testing on your system, and create a "Makefile" which will explain to the "make" utility how the software should be compiled. If you receive any error messages during this stage, you may wish to search the forums to see if they have been found and resolved by someone else already, if not, feel free to post a question on the forums - Please include all of the output including any error messages, and some details about your system - what distro you are using, what are you trying to install etc etc


The next stage is to compile the software, this is done using "make". When you run "make" it will read the instructions in the Makefile and build the application binaries.

Code:

make

The final stage is to install these binaries, ie, copy them to a more permanent location. Typically only the "root" user can do this, so you will need to swich to the root user with the "su" command:

Code:

su

Once you are root, install the binaries using the "make" command, followed by "install", like so:

Code:

make install

That is it! Check the user documentation of the software you installed for details of how to run the application.

Remember that if you have any problems, please post in the most relevant section of the forums. - When posting, remember to include as much info as possible, including all output and error messages.
SOURCE

Special characters, Java ...

If you are wondering how to check special characters in Java with a char variable,you can look @ the meaningless program down here.This program just shows you how to compare special characters with a char variable.
/********************************************
*********************************************
********** Special Char check ***************
*********************************************
********************************************/
public void checkSpecialChar(String aText){
Char character = aText.charAt(0);

if (character == '<') {
System.out.println(aText);
}
else if (character == '>') {
System.out.println(aText);
}
else if (character == '&') {
System.out.println(aText);
}
else if (character == '\"') {
System.out.println(aText);
}
else if (character == '\t') {
System.out.println(aText);
}
else if (character == '!') {
System.out.println(aText);
}
else if (character == '#') {
System.out.println(aText);
}
else if (character == '$') {
System.out.println(aText);
}
else if (character == '%') {
System.out.println(aText);
}
else if (character == '\'') {
System.out.println(aText);
}
else if (character == '(') {
System.out.println(aText);
}
else if (character == ')') {
System.out.println(aText);
}
else if (character == '*') {
System.out.println(aText);
}
else if (character == '+') {
System.out.println(aText);
}
else if (character == ',') {
System.out.println(aText);
}
else if (character == '-') {
System.out.println(aText);
}
else if (character == '.') {
System.out.println(aText);
}
else if (character == '/') {
System.out.println(aText);
}
else if (character == ':') {
System.out.println(aText);
}
else if (character == ';') {
System.out.println(aText);
}
else if (character == '=') {
System.out.println(aText);
}
else if (character == '?') {
System.out.println(aText);
}
else if (character == '@') {
System.out.println(aText);
}
else if (character == '[') {
System.out.println(aText);
}
else if (character == '\\') {
System.out.println(aText);
}
else if (character == ']') {
System.out.println(aText);
}
else if (character == '^') {
System.out.println(aText);
}
else if (character == '_') {
System.out.println(aText);
}
else if (character == '`') {
System.out.println(aText);
}
else if (character == '{') {
System.out.println(aText);
}
else if (character == '|') {
System.out.println(aText);
}
else if (character == '}') {
System.out.println(aText);
}
else if (character == '~') {
System.out.println(aText);
}
else {
//the char is not a special one
//add it to the result as is
System.out.println(aText);
}
}//end of checkSpecialChar(String )
/********************************************
*********************************************
******* End of Special Char check **********
*********************************************
********************************************/
Edited from this source

You dont need to boot to check your eamil, FAST LINUX

Some time ago a company called DeviceVM started to embed Linux into the motherboards of personal computers with the objective to provide an alternative operating system that boots up in a few seconds.

The objective is not to replace the main operating system, which in most cases is still Microsoft Windows, but to enable users to perform common tasks, such as checking email, browsing the Internet, or making a VoIP call immediately after turning on the computer, without the painful process of waiting for the regular OS to be fully up and running.

ASUS has been adopting Splashtop early on and includes it now on most of its motherboards. It is incorporated in the flash memory firmware. Besides the Linux kernel, this includes drivers, networking tools, and various frequently used applications.

RAR @ Fedora ...

By default, Rar is not available in Fedora 10. If all you need to do is extract files from a Rar archive, unrar from RPM Fusion's YUM repositories will work. If you need to create Rar archives, then you will have to download and install the complete Rar package from DAG. The instructions below show you how.

Only Need to Extract Files?

First, install RPM Fusion's free and nonfree YUM repositories. For detailed information about installing RPM Fusion, see: http://rpmfusion.org/Configuration

su -c "rpm -Uvh http://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-stable.noarch.rpm"

su -c "rpm -Uvh http://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-stable.noarch.rpm"

Next, install the unrar packages from RPMFusion's nonfree repository.

su -c "yum install unrar"

Done! You now have unrar in /usr/bin/unrar. This binary can only extract files from Rar archives. Use this command to see all available options:

/usr/bin/unrar -?

Need to Create Rar Archives?

First, download the source RPM from DAG: http://dag.wieers.com/rpm/packages/rar

wget -c http://dag.wieers.com/rpm/packages/rar/rar-3.5.1-1.rf.src.rpm

Now, install the source RPM. This will create a $HOME/rpmbuild tree. Please note that you do not need to be root.

rpm -iv rar-3.5.1-1.rf.src.rpm

Next, build a binary package in $HOME/rpmbuild. Again, no need to be root.

rpmbuild -bb ~/rpmbuild/SPECS/rar.spec

Finally, install the built RPM as root:

su -c "rpm -Uvh $HOME/rpmbuild/RPMS/$(arch)/rar-3.5.1-1.rf.x86_64.rpm"

Done! You now have rar in /usr/bin/rar. This binary can build and extract Rar files. Use this command to see all available options:

/usr/bin/rar -?

Flash Fix @ Ubuntu ...

My flash If you want to completely remove all flash plugins(& install again later), run the following command and then delete the related plugins inside ~/.mozilla/plugins, if there are any:

Code:

sudo apt-get remove swfdec-mozilla
sudo apt-get remove mozilla-plugin-gnash
sudo apt-get remove adobe-flashplugin
sudo apt-get remove flashplugin-nonfree

Keep in mind this will also remove flash plugin from Opera, since it's not Firefox that installed the flash plugin. The flash plugin installation is generic for all browsers.

Nevertheless, I believe your problems is due to conflicting plugins. So before trying to remove all flash plugins, try this(IT WORKED FOR ME):

Code:

sudo apt-get remove swfdec-mozilla
sudo apt-get remove mozilla-plugin-gnash
sudo apt-get remove adobe-flashplugin
sudo apt-get remove flashplugin-nonfree
sudo apt-get install flashplugin-nonfree

From my experience, flash does not play well on any browser. Nevertheless, you might experience better performance with Firefox 3.5.3, which is faster than Opera. The alpha releases of Chromium and Firefox 3.6.1a are the best for flash.

You can also try to improve your flash experience using my tutorial Firefox optimization and troubleshooting thread.
Source : Ubuntu Forums

List of installed programs or packages on Ubuntu

List installed (ii) programs (packages):
$ dpkg -l

$ dpkg -l | less

$ dpkg -l | grep nano

See also
$ ls -l /usr/bin | less

$ man dpkg