#include /* errno */ #include /* fprintf(3), stderr */ #include /* strtol(3) */ #include /* EX_USAGE */ static char *program_name = "retval"; int main(int argc, char *argv[]){ unsigned int s; if(argc < 2) goto usage; errno = 0; s = strtol(argv[1], &argv[1], 10); if(*argv[1] != '\0' || errno != 0){ usage: fprintf(stderr, "Usage: %s [status]\n", argv[0] == NULL ? program_name : argv[0]); return EX_USAGE; } return s; }