Name	Name	Last commit message	Last commit date
parent directory ..
cp_test	cp_test
test_file_I_O	test_file_I_O
test_task_2	test_task_2
.3-cp.c.swp	.3-cp.c.swp
0-main.c	0-main.c
0-main_test9.c	0-main_test9.c
0-read_textfile.c	0-read_textfile.c
1-create_file.c	1-create_file.c
1-main.c	1-main.c
2-append_text_to_file.c	2-append_text_to_file.c
2-main.c	2-main.c
3-cp	3-cp
3-cp.c	3-cp.c
Incitatous	Incitatous
README.md	README.md
Requiescat	Requiescat
_putchar.c	_putchar.c
a	a
b	b
c	c
cp	cp
hello	hello
incitatous	incitatous
main.h	main.h
main_3.c	main_3.c
textfile.txt	textfile.txt
textfile_2.txt	textfile_2.txt
txt	txt

0x15. C - File I/O

C

Syscall

Resources

Read or watch:

File descriptors

C Programming in Linux Tutorial #024 - open() read() write() Functions

man or help:

open

close

read

write

dprintf

Learning Objectives

At the end of this project, you are expected to be able to explain to anyone, without the help of Google:

General

Look for the right source of information online

How to create, open, close, read and write files

What are file descriptors

What are the 3 standard file descriptors, what are their purpose and what are their POSIX names

How to use the I/O system calls open, close, read and write

What are and how to use the flags O_RDONLY, O_WRONLY, O_RDWR

What are file permissions, and how to set them when creating a file with the open system call

What is a system call

What is the difference between a function and a system call

Copyright - Plagiarism

You are tasked to come up with solutions for the tasks below yourself to meet with the above learning objectives.

You will not be able to meet the objectives of this or any following project by copying and pasting someone else’s work.

You are not allowed to publish any content of this project.

Any form of plagiarism is strictly forbidden and will result in removal from the program.

Requirements

General

Allowed editors: vi, vim, emacs

All your files will be compiled on Ubuntu 20.04 LTS using gcc, using the options -Wall -Werror -Wextra -pedantic -std=gnu89

All your files should end with a new line

A README.md file, at the root of the folder of the project is mandatory

Your code should use the Betty style. It will be checked using betty-style.pl and betty-doc.pl

You are not allowed to use global variables

No more than 5 functions per file

The only C standard library functions allowed are malloc, free and exit. Any >- use of functions like printf, puts, calloc, realloc etc… is forbidden

Allowed syscalls: read, write, open, close

You are allowed to use _putchar

You don’t have to push _putchar.c, we will use our file. If you do it won’t be taken into account

In the following examples, the main.c files are shown as examples. You can use them to test your functions, but you don’t have to push them to your repo (if you do we won’t take them into account). We will use our own main.c files at compilation. Our main.c files might be different from the one shown in the examples

The prototypes of all your functions and the prototype of the function _putchar should be included in your header file called main.h

Don’t forget to push your header file

All your header files should be include guarded

Tip: always prefer using symbolic constants (POSIX) vs numbers when it makes sense. For instance read(STDIN_FILENO, ... vs read(0, ...

Tasks

0. Tread lightly, she is near (mandatory)

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$

Repo:

GitHub repository: alx-low_level_programming

Directory: 0x15-file_io

File: 0-read_textfile.c

1. Under the snow (mandatory)

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$

Repo:

GitHub repository: alx-low_level_programming

Directory: 0x15-file_io

File: 1-create_file.c

2. Speak gently, she can hear (mandatory)

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$

Repo:

GitHub repository: alx-low_level_programming

Directory: 0x15-file_io

File: 2-append_text_to_file.c

3. cp (mandatory)

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$

Repo:

GitHub repository: alx-low_level_programming

Directory: 0x15-file_io

File: 3-cp.c

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0x15-file_io

0x15-file_io

README.md

0x15. C - File I/O

C

Syscall

Resources

Read or watch:

man or help:

Learning Objectives

General

Copyright - Plagiarism

Requirements

General

Tasks

0. Tread lightly, she is near (mandatory)

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

Repo:

1. Under the snow (mandatory)

Create a function that creates a file.

Repo:

2. Speak gently, she can hear (mandatory)

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

Repo:

3. cp (mandatory)

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

Repo:

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0x15-file_io

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parent directory

README.md

0x15. C - File I/O

C

Syscall

Resources

Read or watch:

man or help:

Learning Objectives

General

Copyright - Plagiarism

Requirements

General

Tasks

0. Tread lightly, she is near (mandatory)

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

Repo:

1. Under the snow (mandatory)

Create a function that creates a file.

Repo:

2. Speak gently, she can hear (mandatory)

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

Repo:

3. cp (mandatory)

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

Repo: