alx-low_level_programming/0x15-file_io at master · ahmaddev-codes/alx-low_level_programming

Name	Name	Last commit message	Last commit date
parent directory ..
Test	Test	Code: added code for other tasks	May 10, 2023
0-read_textfile.c	0-read_textfile.c	Update: removed trailing whiteline in code	May 9, 2023
1-create_file.c	1-create_file.c	Code: added code to create a file using syscall	May 9, 2023
100-elf_header.c	100-elf_header.c	Code: added code for other tasks	May 10, 2023
2-append_text_to_file.c	2-append_text_to_file.c	Code: modified file	May 10, 2023
3-cp.c	3-cp.c	Code: added code for other tasks	May 10, 2023
Incitatous	Incitatous	Code: added code for other tasks	May 10, 2023
README.md	README.md	Update: added README.md file for task instruction documentation	May 8, 2023
Requiescat	Requiescat	Code: added text file to read	May 9, 2023
hello	hello	Code: added code for other tasks	May 10, 2023
incitatous	incitatous	Code: added code for other tasks	May 10, 2023
main.h	main.h	Code: added code for other tasks	May 10, 2023

0x15-file_io

0-read_textfile.c

Write a function that reads a text file and prints it to the POSIX standard output.

Prototype: ssize_t read_textfile(const char *filename, size_t letters);
where letters is the number of letters it should read and print
returns the actual number of letters it could read and print
if the file can not be opened or read, return 0
if filename is NULL return 0
if write fails or does not write the expected amount of bytes, return 0

julien@ubuntu:~/0x15. File descriptors and permissions$ cat Requiescat 
Requiescat
by Oscar Wilde

Tread lightly, she is near
Under the snow,
Speak gently, she can hear
The daisies grow.

All her bright golden hair
Tarnished with rust,
She that was young and fair
Fallen to dust.

Lily-like, white as snow,
She hardly knew
She was a woman, so
Sweetly she grew.

Coffin-board, heavy stone,
Lie on her breast,
I vex my heart alone,
She is at rest.

Peace, Peace, she cannot hear
Lyre or sonnet,
All my life's buried here,
Heap earth upon it.
julien@ubuntu:~/0x15. File descriptors and permissions$ cat 0-main.c
#include <stdio.h>
#include <stdlib.h>
#include "main.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(int ac, char **av)
{
    ssize_t n;

    if (ac != 2)
    {
        dprintf(2, "Usage: %s filename\n", av[0]);
        exit(1);
    }
    n = read_textfile(av[1], 114);
    printf("\n(printed chars: %li)\n", n);
    n = read_textfile(av[1], 1024);
    printf("\n(printed chars: %li)\n", n);
    return (0);
}
julien@ubuntu:~/0x15. File descriptors and permissions$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 0-main.c 0-read_textfile.c -o a
julien@ubuntu:~/0x15. File descriptors and permissions$ ./a Requiescat 
Requiescat
by Oscar Wilde

Tread lightly, she is near
Under the snow,
Speak gently, she can hear
The daisies grow.
(printed chars: 114)
Requiescat
by Oscar Wilde

Tread lightly, she is near
Under the snow,
Speak gently, she can hear
The daisies grow.

All her bright golden hair
Tarnished with rust,
She that was young and fair
Fallen to dust.

Lily-like, white as snow,
She hardly knew
She was a woman, so
Sweetly she grew.

Coffin-board, heavy stone,
Lie on her breast,
I vex my heart alone,
She is at rest.

Peace, Peace, she cannot hear
Lyre or sonnet,
All my life's buried here,
Heap earth upon it.

(printed chars: 468)
julien@ubuntu:~/0x15. File descriptors and permissions$

1-create_file.c

Create a function that creates a file.

Prototype: int create_file(const char *filename, char *text_content);
where filename is the name of the file to create and text_content is a NULL terminated string to write to the file
Returns: 1 on success, -1 on failure (file can not be created, file can not be written, write “fails”, etc…)
The created file must have those permissions: rw-------. If the file already exists, do not change the permissions.
if the file already exists, truncate it
if filename is NULL return -1
if text_content is NULL create an empty file

julien@ubuntu:~/0x15. File descriptors and permissions$ cat 1-main.c
#include <stdio.h>
#include <stdlib.h>
#include "main.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(int ac, char **av)
{
    int res;

    if (ac != 3)
    {
        dprintf(2, "Usage: %s filename text\n", av[0]);
        exit(1);
    }
    res = create_file(av[1], av[2]);
    printf("-> %i)\n", res);
    return (0);
}
julien@ubuntu:~/0x15. File descriptors and permissions$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 1-main.c 1-create_file.c -o b
julien@ubuntu:~/0x15. File descriptors and permissions$ ./b hello world
-> 1)
julien@ubuntu:~/0x15. File descriptors and permissions$ ls -l hello
-rw------- 1 julien julien 5 Dec  3 14:28 hello
julien@ubuntu:~/0x15. File descriptors and permissions$ cat hello 
worldjulien@ubuntu:~/0x15. File descriptors and permis$

2-append_text_to_file.c

Write a function that appends text at the end of a file.

Prototype: int append_text_to_file(const char *filename, char *text_content);
where filename is the name of the file and text_content is the NULL terminated
string to add at the end of the file Return: 1 on success and -1 on failure Do not create the file if it does not exist If filename is NULL return -1 If text_content is NULL, do not add anything to the file. Return 1 if the file exists and -1 if the file does not exist or if you do not have the required permissions to write the file

julien@ubuntu:~/0x15. File descriptors and permissions$ cat 2-main.c
#include <stdio.h>
#include <stdlib.h>
#include "main.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(int ac, char **av)
{
    int res;

    if (ac != 3)
    {
        dprintf(2, "Usage: %s filename text\n", av[0]);
        exit(1);
    }
    res = append_text_to_file(av[1], av[2]);
    printf("-> %i)\n", res);
    return (0);
}
julien@ubuntu:~/0x15. File descriptors and permissions$ echo -n Hello > hello
julien@ubuntu:~/0x15. File descriptors and permissions$ ls -l hello
-rw-rw-r-- 1 julien julien 5 Dec  3 14:48 hello
julien@ubuntu:~/0x15. File descriptors and permissions$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 2-main.c 2-append_text_to_file.c -o c
julien@ubuntu:~/0x15. File descriptors and permissions$ ./c hello " World!
> "
-> 1)
julien@ubuntu:~/0x15. File descriptors and permissions$ cat hello 
Hello World!
julien@ubuntu:~/0x15. File descriptors and permissions$

3-cp.c

Write a program that copies the content of a file to another file.

Usage: cp file_from file_to
if the number of argument is not the correct one, exit with code 97 and print Usage: cp file_from file_to, followed by a new line, on the POSIX standard error
if file_to already exists, truncate it
if file_from does not exist, or if you can not read it, exit with code 98 and print Error: Can't read from file NAME_OF_THE_FILE, followed by a new line, on the POSIX standard error
- where NAME_OF_THE_FILE is the first argument passed to your program
if you can not create or if write to file_to fails, exit with code 99 and print Error: Can't write to NAME_OF_THE_FILE, followed by a new line, on the POSIX standard error
- where NAME_OF_THE_FILE is the second argument passed to your program
if you can not close a file descriptor , exit with code 100 and print Error: Can't close fd FD_VALUE, followed by a new line, on the POSIX standard error
- where FD_VALUE is the value of the file descriptor
Permissions of the created file: rw-rw-r--. If the file already exists, do not change the permissions
You must read 1,024 bytes at a time from the file_from to make less system calls. Use a buffer
You are allowed to use dprintf

julien@ubuntu:~/0x15. File descriptors and permissions$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 3-cp.c -o cp
julien@ubuntu:~/0x15. File descriptors and permissions$ cat incitatous 
Why you should think twice before putting pictures on social media.
(What you always wanted to know about @Incitatous)
#PrivacyAware
http://imgur.com/a/Mq1tc
julien@ubuntu:~/0x15. File descriptors and permissions$ ./cp incitatous Incitatous
julien@ubuntu:~/0x15. File descriptors and permissions$ ls -l Incitatous 
-rw-rw-r-- 1 julien julien 158 Dec  3 15:39 Incitatous
julien@ubuntu:~/0x15. File descriptors and permissions$ cat Incitatous 
Why you should think twice before putting pictures on social media.
(What you always wanted to know about @Incitatous)
#PrivacyAware
http://imgur.com/a/Mq1tc
julien@ubuntu:~/0x15. File descriptors and permissions$

100-elf_header.c

Write a program that displays the information contained in the ELF header at the start of an ELF file.

Usage: elf_header elf_filename
Displayed information: (no less, no more, do not include trailing whitespace)
- Magic
- Class
- Data
- Version
- OS/ABI
- ABI Version
- Type
- Entry point address
Format: the same as readelf -h (version 2.26.1)
If the file is not an ELF file, or on error, exit with status code 98 and display a comprehensive error message to stderr
You are allowed to use lseek once
You are allowed to use read a maximum of 2 times at runtime
You are allowed to have as many functions as you want in your source file
You are allowed to use printf

man elf, readelf

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0x15-file_io

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README.md

0x15-file_io

0-read_textfile.c

1-create_file.c

2-append_text_to_file.c

3-cp.c

100-elf_header.c

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0x15-file_io

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