opendir(), closedir(), readdir() and dirent system call.

/* C program read all text files from a directory */

            Different file system types may have different directory entries. The dirent structure defines a file system independent directory entry, which contains information common to directory entries in different file system types. A set of these structures is returned by the getdents(2) system call.

The dirent structure is defined as:

         #include<sys/dirent.h>

                            

           struct dirent

           {

               long d_ino; /* inode number */

               off_t d_off; /* offset to the next dirent */

               unsigned short d_reclen; /* length of this record */

              unsigned char d_type; /* type of file */

               char d_name[256];  /* filename*/

            };

     

   d_ino          …..       inode number of a file

   d_offset      …..      offset of that directory entry in the actual file system directory

   d_name       …..     name of the file or directory

    d_reclen                 record length of this entry

    d_type        …..     type of file( text file, block file, directory etc)

/* Unix program to read all text files from a directory */

/printfile.c*/

#include<stdio.h>

#include<dirent.h>

#include<stdlib.h>

void main()

{

    DIR *dirp;

    struct dirent *dp;

    if((dirp=opendir("/home/kumar"))==NULL)  /* trying to open kumar directory*/

    {

       printf("\n cannot open");

       exit(1);

    }

    for(dp=readdir(dirp);dp!=NULL;dp=readdir(dirp))

    {

        if(dp->d_type==DT_REG)   /* printing only if file is a text file */

        printf("%s\n",dp->d_name);

    }

    closedir(dirp);

}

output:

            /home/kumar/~$ cc printfile.c

            /home/kumar/~$ ./a.out

             hello.sh

             count.sh

             check.sh

             semlock.c

             pipedemo.c

opendir(), closedir(), readdir() and dirent system call. C program read all text files from a directory. c program to print directory structure. c program to print no of hard links and soft links of a given file