/******************************************************************
 * Created: Josep Valls 20080111
 * Modified: Josep Valls 20080124
 * Timer assignment for CMPS105/Winter2008
 * Practice the use of fork, system and gettimeofday
 ******************************************************************/

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
	pid_t pid;
	int retval;
	if (argc<2){
		printf("No command nor parameters were specified.\n");
		exit(0);
	}

	//Start timer
	struct timeval *run_time;
	time_t elapsed_sec;
	long elapsed_usec;
	gettimeofday(run_time,NULL);
	elapsed_sec=run_time->tv_sec;
	elapsed_usec=run_time->tv_usec;

	if (argc>2){
		//Execute the command with its parameters
		printf("Running (execvp): %s\n",argv[1]);
		pid=fork();
		if(pid==0)
			execvp(argv[1],&argv[1]);
		else
			wait(&retval);
	}else{
		//Execute the command without any parameters
		printf("Running (system): %s\n",argv[1]);
		system(argv[1]);
	}

	//Compute timer
	gettimeofday(run_time,NULL);
	elapsed_sec=run_time->tv_sec-elapsed_sec;
	elapsed_usec=run_time->tv_usec-elapsed_usec;
	//Modified 20080124: Proper timming representation
	printf("Process completed in %d microsecs.\n",elapsed_usec+(elapsed_sec*1000000));
}