Linux Program to Read from a File using File Descriptors

This Linux Program illustrates Reading from a File using File Descriptors.

Here is the source code of Linux Program to Read from a File Using File Descriptors. The Linux Program is successfully compiled and run on a Linux system. The program output is also shown below.

```
/*
```

* Linux Program to Read from a File using File Descriptors.

```
*/
```
```
 
```
```
#include <stdio.h>
```
```
#include <sys/types.h>
```
```
#include <sys/stat.h>
```
```
#include <fcntl.h>
```
```
#include <unistd.h>
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```
#include <errno.h>
```
```
#include <stdlib.h>
```
```
 
```
```
int main(int argc, char **argv)
```
```
{
```
```
    int fd,retval;
```
```
    char *buffer;    
```
```
 
```
```
    if (argc < 2) {
```

        printf("Usage : %s pathname\n", argv[0]);

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        exit(1);
```
```
    }
```
```
 
```

    /*opening the file in read-only mode*/

    if ((fd = open(argv[1], O_RDONLY)) < 0) {

        perror("Problem in opening the file");

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        exit(1);
```
```
    }
```
```
 
```

    /*reading bytes from the fd and writing it to the buffer*/

    while ((retval = read(fd, buffer, 1)) > 0)

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        printf("%c", *buffer);    
```
```
    if (retval < 0) {
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        perror("\nRead failure");
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        exit(1);
```
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    }
```

    printf("\nSuccessfully read bytes from the file %s\n", argv[1]);

```
 
```
```
    close(fd);
```
```
}
```

$ echo "hello san" > my_file
$ gcc read_file.c
$ ./a.out my_file
 
hello san 
Successfully read bytes from the file my_file

Sanfoundry Global Education & Learning Series – 1000 Linux Programs.

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