Functions.txt

int commandExecution( {command format} )
{

	
	pid_t pid;
	
	pid = fork();
	
	if(pid < 0)
	{
		cerr << "fork failed" << endl;
		exit(0);
	}
	else if( pid == 0)
	{
		
	}
	
}

int execute( argv)



int redirectToFile( const string & filename)
{
	
	FILE * inFile = fopen (filename.c_str(), "r");
	if(inFile == NULL)
	{
		
	}
	else
	{
		
	}

}


//#include <signal.h>
//#include <cstring>
//#include <iostream>
void kill( string *cmds)
{

	if(cmds[1].empty())
	{
		cerr << "Must pass ID number of process to kill" << endl;
		return;
	}
	if(kill(atoi(cmds[1].c_str()), SIGKILL) != 0)
	{
		cerr << "Error, Process could not be killed" << endl;
	}

}




//#include <unistd.h>
//#include <cstring>
//#include <iostream>
void cd( string *cmds)
{
	if(!cmds[1].empty())
	{
		//absolute path given
		if(cmds[1][0] == '/')
		{
			if(chdir(cmds[1].c_str()) != 0)
				cerr << "Error, invalid directory: " << cmds[1] << endl;
		}
		//dosen't start with '/' so relitive path given
		else
		{
			string workingdir = get_current_dir_name();
			if(chdir((workingdir + "/" + cmds[1]).c_str()) != 0)
				cerr << "Error, invalid directory: " << cmds[1] << endl;
		}
	}
	//only cd given as argument so change to home directory
	else
		if(chdir(getenv("HOME")) != 0)
			cerr << "Error, couldn't change directory to: " << getenv("HOME") << endl;
			
}



void set( string *cmds)
{

	if(cmds[1].empty())
	{
		cerr << "Error, No enviroment specified" << endl;
		return;
	}
	
	if(strncmp(cmds[1].c_str(), "HOME=", 5) == 0)
	{
		if(setenv("HOME", &cmds[1][5],1) == -1)
			cerr << "Error, could not set HOME" << endl;
	}
	if(strncmp(cmds[1].c_str(), "PATH=", 5) == 0)
	{
		if(setenv("PATH", &cmds[1][5],1) == -1)
			cerr << "Error, could not set PATH << endl;
	}

}


//Basic Zombie reaping with sigaction()
//#include <signal.h>
//#include <sys/wait.h>

void sigchld_handler(int s)
{
	while(waitpid(-1, NULL, WNOHANG) > 0);
}

void reaper()
{
	struct sigaction sa;
	
	sa.sa_handler = sigchld_handler; //reaps all dead processes
	sigemptyset(&sa.sa_mask);
	sa.sa_flags = SA_RESTART;
	if(sigaction(SIGCHLD, &sa, NULL) == -1
	{
		perror("sigaction");
		exit(1);
	}
}