main(argc, argv) int argc; char **argv; { int m, a, b; if(argc != 5) { printf("arg count\n"); goto usage; } if(*argv[2] == 'b') m = 060666; else if(*argv[2] == 'c') m = 020666; else goto usage; a = number(argv[3]); if(a < 0) goto usage; b = number(argv[4]); if(b < 0) goto usage; if(mknod(argv[1], m, (a<<8)|b) < 0) perror("mknod"); exit(0); usage: printf("usage: mknod name b/c major minor\n"); } number(s) char *s; { int n, c; n = 0; while(c = *s++) { if(c<'0' || c>'9') return(-1); n = n*10 + c-'0'; } return(n); }