main(argc, argv) char **argv; { int c, n; char *s; n = 0; if(argc < 2) { printf("arg count\n"); exit(0); } s = argv[1]; while(c = *s++) { if(c<'0' || c>'9') { printf("bad character\n"); exit(0); } n = n*10 + c - '0'; } sleep(n); }