#include /** ** User function main #4: exit, fork, exec, sleep, write ** ** Loops, spawning N copies of userX and sleeping between spawns. ** ** Invoked as: main4 x n ** where x is the ID character ** n is the iteration count (defaults to 5) */ USERMAIN(main) { int count = 5; // default iteration count char ch = '4'; // default character to print int nap = 30; // nap time char msg2[] = "*4*"; // "error" message to print char buf[32]; // process the command-line arguments switch (argc) { case 3: count = str2int(argv[2], 10); // FALL THROUGH case 2: ch = argv[1][0]; break; default: sprint(buf, "main4: argc %d, args: ", argc); cwrites(buf); for (int i = 0; i <= argc; ++i) { sprint(buf, " %s", argv[argc] ? argv[argc] : "(null)"); cwrites(buf); } cwrites("\n"); } // announce our presence write(CHAN_SIO, &ch, 1); // argument vector for the processes we will spawn char *arglist[] = { "userX", "X", buf, NULL }; for (int i = 0; i < count; ++i) { write(CHAN_SIO, &ch, 1); // second argument to X is 100 plus the iteration number sprint(buf, "%d", 100 + i); int whom = spawn(ProgX, arglist); if (whom < 0) { swrites(msg2); } else { write(CHAN_SIO, &ch, 1); } sleep(SEC_TO_MS(nap)); } exit(0); return (42); // shut the compiler up! }