src/retval/retval.c

#include <errno.h> /* errno */
#include <stdio.h> /* fprintf(3), stderr */
#include <stdlib.h> /* strtol(3) */
#include <sysexits.h> /* EX_USAGE */

static char *program_name = "retval";

int main(int argc, char *argv[]){
	unsigned int s;

	if(argc < 2){
usage:		fprintf(stderr, "Usage: %s [status]\n", argv[0] == NULL ? program_name : argv[0]);
		return EX_USAGE;
	}

	errno = 0;
	s = strtol(argv[1], &argv[1], 10);
	if(*argv[1] != '\0' || errno != 0)
		goto usage;

	return s;
}