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programming-fr34ks net ; linux arabic programming tutorialauthor : St0rM-MaNlicense : Rippers License , Gnu/Gpl ; based on : advanced linux programming

OMG!!! Linux Programmin

Cool Ain't :DVisit Us ( Http://Programming-Fr34ks.Net ) ;

friends :http://securitygurus.net http://arab4services.com

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: Programming-Fr34ks.net :

:

1 linux 1

2 2 root directory

directories directories

/home/St0rM/Desktop/File c dir homedir St0rM dir Desktop

3 linux dir 3 Linux sockets

socket dirs d Linux 4

r = readw = writex = execute

type users{r/w/x} , groups{ r/w/x} , others{ r/w/x}dirs d

hard link ) )

4 4 dirs sockets pipe fifo

5 5 read , write bytes

binary bytes streams bytes

6 6 255

XX xx )

( linux dir

this/is/me txt me txt this/me

http://linuxac org/forum/showthread php?t=1586

http://linuxac.org/forum/showthread.php?t=1586http://linuxac.org/forum/showthread.php?t=1586

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.

7 7

8 8

memory addresses

files descriptors ( )

stander portable C standard files manipulating functions

files descriptor

file descriptor ) )

C standard files manipulating functions

datac structure FILE

...

9

10

#include

int main void{

FILE* file_to_open;

structure file (stdio typedef data structure

#include

FILE *fopen const char * restrict path , const char * restrict mode ;

FILE structure

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mode

r , w , a

FILE structure (

( r+ , w+ , a+

.

.

NULL perror .

Int fclose FILE *file ;

#include#include#include

int main void{

FILE* file_to_open;

file_to_open = fopen "textfile" , "r+" ;

if file_to_open == NULL

{ perror "fopen " ;_exit 1 ;

}fclose file_to_open ;

return 0;}

.

fgets , fputs , fprintf , fscanf , fputc , fgetc ;

char *fgets char * restrict str , int size , FILE * restrict stream ;

str size stream

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stream ) enter )str

.

stdin streams.

/etc/services

#include#include#include

int main void{

FILE* file_to_open;char buffer[81]; /*enough to hold one line*/

file_to_open = fopen "/etc/services" , "r" ; /*open for read and write if exist*/

if file_to_open == NULL{

perror "fopen " ;_exit 1 ;

}

fgets buffer , 250 , file_to_open ;printf "File /etc/services first line is\n"

"%s",buffer ;fclose file_to_open ;

return 0;}

#include

int fputs const char *str , FILE *stream ;

str stream

#include

#include

#include

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int main void

{

FILE* file_to_open;

char buffer[81]; /*enough to hold one line*/

file_to_open = fopen "test" , "w" ; /*open for read and write if exist*/

strcpy buffer , "Hello Files\n" ; /*copy our string */

if file_to_open == NULL

{

perror "fopen " ;

_exit 1 ;

}

fputs buffer , file_to_open ; /*write it */

printf "File test file has line \n"

"%s",buffer ;

fclose file_to_open ;

return 0;

}

file_to_read ;rewind

void

rewind FILE *stream ;

long

ftell FILE *stream ;

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int

fseek FILE *stream , long offset , int whence ;

rewind rewind fseek ) (bytes

#include

#include

#include

#include

int main void

{

FILE* file_to_open;

char buffer[81]; /*enough to hold one line*/

char buf[81]; /*enough to read one line*/

unsigned long int pos;

file_to_open = fopen "test txt" , "w+" ; /*open for read and write if exist*/

strcpy buffer , "Hello Files\n" ; /*copy our string */

if file_to_open == NULL

{

perror "fopen " ;

_exit 1 ;

}

fputs buffer , file_to_open ; /*write it */

rewind file_to_open ;

pos = ftell file_to_open ;

printf "Current position %lu\n",pos ;

fgets buf , 81 , file_to_open ;

printf "File test has %s\n",buf ;

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P_SHLOCK , O_EXLOCK =

O_RDONLY =

O_WRONLY =

O_APPEND =

O_RDWR =

modes permissions access users

S_IRWXU ,S_IRUSR , S_IWUSR , S_IXUSR users ; = read/write , read , write , execute

S_IRWXG , S_IRGRP , S_IWGRP , S_IXGRP groups ; = read/write , read , write , execute

S_IROTH , S_IROTH , S_IWOTH , S_IXOTH others ; = read/write , read , write , execute

12 modes flags ?

bitwise| oring flags modes

(users (

int fd;

fd = open "test txt" , O_CREAT O_EXCL , I_RWUSR ;

int fd;

fd = open "test txt" , O_CREAT O_TRUCN , I_RWUSR I_RWGRP , I_RWOTH ;

#include

int close ( int d );

file descriptor .

.

file descriptor hard link ! unlink )(link !

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file descriptors hard links.

open 1 file descriptor . perror .

13

read , write.

#include

#include

ssize _ tread( int d , void *buf , size _ t nbytes );

file descriptor d

buf nbytes d

nbytes

d

#include

#include

#include

#include

int main(void)

{

int fd;

char buf[80];

size_t bytes_read;

fd = open("test.txt" , O_RDONLY);

bytes_read = read(fd , buf , sizeof(buf));

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if(bytes_read < 0)

{

perror("read()");

_exit(1);

}

buf[bytes_read] = '\x0';

printf("%s with length %d\n",buf , (int)bytes_read);

close(fd);

}

read bytes

0 perror

terminating character

read

14

.write

ssize _ t

write ( int d , const void *buf , size _ t nbytes );

fd .buf

Hello World

#include

#include

#include

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#include

#include

int main(void)

{

int fd;

char buf[80];

size_t bytes_write;

fd = open("test.txt" , O_WRONLY);

strcpy(buf , "Hello World");

bytes_write = write(fd , buf , strlen(buf));

if(bytes_write < 0)

{

perror("read()");

_exit(1);

}

printf("%s with length %d has been written\n",buf , (int)bytes_write);

close(fd);

}

15

#include

off _ t lseek ( int fildes , off _ t offset , int whence );

whenceoffest bytes 10

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lseek(fd , 10 , SEEK_CUR);

10 bytes

lseek(fd , 10 , SEEK_SET);

man pages

file .ftell

.

bytes

.

.

dirs.