Operating System

LS command

LS

ls - list files in folder

ls

We use C program to list files in a directory. The program is as follows:

#include <stdio.h>
#include <dirent.h>
#include <sys/types.h>
#include <string.h>

int main(int argc, char *argv[]) {
    char *dir_path = argv[1];
    DIR *dir = opendir(dir_path);
    if (dir == NULL) {
        perror("opendir failed");
        return 1;
    }
    struct dirent *entry;
    while ((entry = readdir(dir)) != NULL) {
        if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) {
            continue;
        }
        printf("%s\n", entry->d_name);
    }
    closedir(dir);
    return 0;
}

To compile and run the program, use the following commands(dont copy the $ sign, it represents the terminal prompt):

$ gcc ls.c -o ls
$ ./ls /path/to/directory

This will list all the files in the directory specified.

Questions

What is the use of ls command?

ls command is used to list files in a directory.

What is the difference between ls and ls -a command?

ls command lists all files in a directory whereas ls -a lists all files including hidden files.

What is the use of opendir function?

opendir function is used to open a directory stream.

What is the use of readdir function?

readdir function is used to read the next entry in the directory stream.