utils-std

echo.c (995B)

// utils-std: Collection of commonly available Unix tools
// SPDX-FileCopyrightText: 2017 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
// SPDX-License-Identifier: MPL-2.0
#define _POSIX_C_SOURCE 200809L
#include <stdbool.h>
#include <stdio.h>  // perror
#include <string.h> // strlen
#include <unistd.h> // write
int
main(int argc, char *argv[])
{
	size_t arg_len = 0;
	bool opt_n = false;
	argc--;
	argv++;
	if(argc > 0 && strncmp(*argv, "-n", 3) == 0)
	{
		opt_n = true;
		argc--;
		argv++;
	}
	for(int i = 0; i < argc; i++)
	{
		size_t len = strlen(argv[i]);
		argv[i][len] = ' ';
		arg_len += len + 1; // str + space
	}
	if(arg_len == 0)
	{
		if(opt_n) return 0;
		if(write(1, "\n", 1) < 1)
		{
			perror("echo: Write error");
			return 1;
		}
		return 0;
	}
	else
		argv[0][arg_len - 1] = '\n';
	if(opt_n) arg_len--; // no newline
	ssize_t nwrite = write(1, *argv, arg_len);
	if(nwrite < (ssize_t)arg_len)
	{
		perror("echo: Write error");
		return 1;
	}
	return 0;
}