1   
    2   #include <stdio.h>
    3   #include <stdlib.h>
    4   #include <unistd.h>
    5   
    6   int main(int argc, char *argv[])
    7   {
    8     char ch = 'X';
    9     int i;
   10   
   11     if ( argc >= 2 ) {
   12       ch = argv[1][0];
   13     }
   14   
   15     printf("argc = %d\n", argc);
   16     for(i = 0; i < argc; i++) {
   17       printf("%s ", argv[i]);
   18     }
   19     printf("\n");
   20   
   21     printf("pid %d: %c\n", getpid(), ch);
   22     if (ch == 'X') {
   23       return 0;
   24     } else if (ch == 'A') {
   25       return 1;
   26     } else if (ch == 'B') {
   27       return 2;
   28     } else if (ch == 'C') {
   29       return 3;
   30     } else {
   31       return 99;
   32     }
   33   
   34   }