fases/head.c

/*	head - print file until a certain line
 *	Copyright (C) 2022 Ferass EL HAFIDI
 *
 *	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 <https://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void printUsage() {
	printf("Ferass' Base System.\n\n"
		"Usage: head [FILE] [-n NUMBER]\n\n"
		"Print FILE's contents until line NUMBER.\n\n"
		"\t-n NUMBER\tPrint first NUMBER line(s).\n"
	);
}

int main(int argc, char *argv[]) {
	FILE *file;
	char s[512], arg_lines;
	int i = 0, usedargs = 0;

	setvbuf(stdout, NULL, _IONBF, 0);

	if (argc == 1) {
		while (1) {
			char input[80];
			fgets(input, 80, stdin);
			printf("%s", input);
		}
	}

	for (i = 1; argv[i]; i++) {
		if (argv[i][usedargs + 1] == 'n' && argv[i + 1]) {
			arg_lines = strtol(argv[i + 1], NULL, 0);
			usedargs++;
		}
		if (argv[i][usedargs + 1] == 'h') {
			printUsage();
			return 0;
		}
	}
	if ((file = fopen(argv[1], "r")) == NULL) {
		printf("head: %s: No such file or directory\n", argv[1]);
		return 1;
	}
	for (; i != arg_lines && (fgets(s, 512, file)) != NULL; i++) {
		s[strcspn(s, "\n")] = 0; /* Remove trailing newline */
		puts(s); 
	}
	fclose(file);

	return 0;
}