toaruos/apps/echo.c

/* vim: tabstop=4 shiftwidth=4 noexpandtab
 * This file is part of ToaruOS and is released under the terms
 * of the NCSA / University of Illinois License - see LICENSE.md
 * Copyright (C) 2013-2018 K. Lange
 *
 * echo - Print arguments to stdout.
 *
 * Prints arguments to stdout, possibly interpreting escape
 * sequences in the arguments.
 */
#include <stdio.h>
#include <string.h>
#include <unistd.h>

void show_usage(char * argv[]) {
	printf(
			"echo - print arguments\n"
			"\n"
			"usage: %s [-ne] ARG...\n"
			"\n"
			" -n     \033[3mdo not output a new line at the end\033[0m\n"
			" -e     \033[3mprocess escape sequences\033[0m\n"
			" -?     \033[3mshow this help text\033[0m\n"
			"\n", argv[0]);
}

int main(int argc, char ** argv) {
	int use_newline     = 1;
	int process_escapes = 0;

	int opt;
	while ((opt = getopt(argc, argv, "enh?")) != -1) {
		switch (opt) {
			case '?':
			case 'h':
				show_usage(argv);
				return 1;
			case 'n':
				use_newline = 0;
				break;
			case 'e':
				process_escapes = 1;
				break;
		}
	}

	for (int i = optind; i < argc; ++i) {
		if (process_escapes) {
			for (int j = 0; j < (int)strlen(argv[i]) - 1; ++j) {
				if (argv[i][j] == '\\') {
					if (argv[i][j+1] == 'e') {
						argv[i][j] = '\033';
						for (int k = j + 1; k < (int)strlen(argv[i]); ++k) {
							argv[i][k] = argv[i][k+1];
						}
					}
					if (argv[i][j+1] == 'n') {
						argv[i][j] = '\n';
						for (int k = j + 1; k < (int)strlen(argv[i]); ++k) {
							argv[i][k] = argv[i][k+1];
						}
					}
				}
			}
		}
		printf("%s",argv[i]);
		if (i != argc - 1) {
			printf(" ");
		}
	}

	if (use_newline) {
		printf("\n");
	}

	fflush(stdout);
	return 0;
}