This is a simple version of ls(1) using C.

myls.c

/*
*  This program is free software: you can redistribute it and/or modify
*  it under the terms of the GNU General Public License as published by
*  the Free Software Foundation, either version 3 of the License, or
*  (at your option) any later version.
*
*  This program is distributed in the hope that it will be useful,
*  but WITHOUT ANY WARRANTY; without even the implied warranty of
*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*  GNU General Public License for more details.
*
*  You should have received a copy of the GNU General Public License
*  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/********************************************************************
* Description: A version of LS written in C.
* Author: John Cartwright <>
* Created at: Mon Apr  3 10:38:18 AEST 2023
* Computer: localhost.localdomain
* System: Linux 5.14.0-162.18.1.el9_1.x86_64 on x86_64
*
* Copyright (c) 2023 John Cartwright  All rights reserved.
*
********************************************************************/

#include <dirent.h>
#include <stdio.h>
#include <sys/stat.h>
#include <string.h>
#include <limits.h>

void list_files(const char *path) {
    struct dirent *entry;
    struct stat file_stat;
    char full_path[PATH_MAX];

    DIR *dir = opendir(path);

    if (dir == NULL) {
        perror("opendir");
        return;
    }

    while ((entry = readdir(dir)) != NULL) {
        if (strcmp(entry->d_name, ".") == 0) {
            continue;
        }

        snprintf(full_path, sizeof(full_path), "%s/%s", path, entry->d_name);

        if (stat(full_path, &file_stat) < 0) {
            perror("stat");
            continue;
        }

        printf("%s", S_ISDIR(file_stat.st_mode) ? "d" : "-");
        printf("%s", (file_stat.st_mode & S_IRUSR) ? "r" : "-");
        printf("%s", (file_stat.st_mode & S_IWUSR) ? "w" : "-");
        printf("%s", (file_stat.st_mode & S_IXUSR) ? "x" : "-");
        printf("%s", (file_stat.st_mode & S_IRGRP) ? "r" : "-");
        printf("%s", (file_stat.st_mode & S_IWGRP) ? "w" : "-");
        printf("%s", (file_stat.st_mode & S_IXGRP) ? "x" : "-");
        printf("%s", (file_stat.st_mode & S_IROTH) ? "r" : "-");
        printf("%s", (file_stat.st_mode & S_IWOTH) ? "w" : "-");
        printf("%s", (file_stat.st_mode & S_IXOTH) ? "x" : "-");
        printf(" %ld ", file_stat.st_size);
        printf("%s\n", entry->d_name);
    }

    closedir(dir);
}

int main(int argc, char *argv[]) {
    if (argc == 1) {
        list_files(".");
    } else {
        printf("%s", argv[1]);
        list_files(argv[1]);
    }

    return 0;
}