errno.c

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

int main(int argc, char *argv[])
{
	if (argc < 2) {
		printf("usage: errno <num> [num ...]\n");
		exit(1);
	}

	int c;
	for (c = 1; c < argc; c++) {
		int i = strtol(argv[c], NULL, 0);
		printf("errno %d is \"%s\".\n", i, strerror(i));
	}

	exit(0);
}