Implement the ExecV system call.
ExecV is like Exec, except that it allows an array of parameters to be passed to the newly created process. From syscall.h:
/* Run the executable, stored in the Nachos file "argv[0]", with
 * parameters stored in argv[1..argc-1] and return a
 * unique non-negative process identifier for the new process.
 * Returns a negative value in case of failure.
 * A few example error codes might be:
 *    NACHOS_ENAMETOOLONG path to executable uses too many characters
 *    NACHOS_EREACHEDLIMIT too many arguments to handle properly
 *    NACHOS_EINVAL one or more arguments is not valid
ProcessId ExecV(int argc, char* argv[]);

The application running in the new process should be able to access these parameters through the argc and argv parameters to the application's main function. For example the following C program (PrintArgs) will print out all of its command line arguments.
#include "syscall.h"

main(int argc, char *argv[])
  int i;

  for (i=0; i<argc; i++) {
    print("Arg ");
    print(" = ");

So for example if another program starts the program above as follows:
char *pgm = "PrintArgs";
char *arg1 = "1";
char *arg2 = "2";
char *arg2 = "arg3";
char *arg3 = "thatsall";
char *arglist[5];
arglist[0] = pgm;
arglist[1] = arg1;
arglist[2] = arg2;
arglist[3] = arg2;
arglist[4] = arg3;

ExecV(5, arglist);
Would result in the following output:
Arg 0 = PrintArgs
Arg 1 = 1
Arg 2 = 2
Arg 3 = arg3
Arg 4 = thatsall