#include "kernel/types.h" #include "kernel/stat.h" #include "user/user.h" int main(int argc, char *argv[]) { int pid; for(int i = 0; i < 4; i++){ pid = fork(); if(pid == 0){ char* argv[] = {"print", "X", 0}; argv[1][0] = 'A' + i; exec("/print", argv); exit(1); } } while(wait(0) != -1); exit(0); }