CS 485G Project 4
Ethan Gill
Mazin Zakaria

Sish is a simple shell.

Files:
	sish.cpp

To compile sish:
	make

To delete compiled files:
	make clean

To run:
	cd to the directory sish is in.
	./sish
	At the prompt, type commands.
	sish > (command goes here)

To run by passing a file:
	cd to the directory sish is in.
	Place the file you want to run in the same directory (optional, but recommended)
	./sish < filename
	OR
	./sish < ./filename

Design Choices:
	- Assignto must take a variable in the form of $var, rather than var.
	- Comments must be on their own line.
	- Setting the PATH variable resets its value.

Known Limitations:
	- When invoking sish and passing a file (for example: "sish < testfile"), 
		there MUST be an extra blank line below the last command, or the final command will not be executed.
			

Sish accepts the following commands:
	Comments
		# A comment can go here.
	Variable Assignments
		variable = value
	Changing Shell Prompt
		defprompt prompt
		defprompt "multi word prompt >"
	Changing Directory
		cd directoryName
	List Background Processes
		listprocs
	Quit
		bye
	Run Programs
		run cmd params [<bg>]
	Assign Run Result to Variable
		assignto variable cmd params

Special Variables:
	PATH
		A colon-separated list of directories to search for programs in. Defaults to "/bin:/usr/bin"
		PATH = "/bin:/usr/bin"
	ShowTokens
		A variable that lets the shell know whether or not to show parser and scanner (debug) information. 1=YES, 0=NO
		ShowTokens = 1
		ShowTokens = 0

Supplementary Functions:
	// Gets the type of each token
string typeGet(string token);
	// Converts a string to an uppercase string for input checking purposes
string upper(string s);
	// Returns a tokenized vector
vector<Token> scanner(string s);
	// Parses the input, checks for correctness
bool parser(vector<Token> &scanned);
	// Runs the given function
void programRun(vector<Token> &parsed);
	// Shows info about the variables
void showInfo(vector<Token> tokens);
	// Returns the variable value given a variable name
string variableValue(string variable);
	// Executes a function when the command is run
bool execute(const char *program, vector<const char*> arguments, bool background);
	// Converts a string to a char *
char * convertToCharStar(string argument);
	// Parses the PATH variable and returns a tokenized vector
vector<string> pathScanner(string s);
	// Executes a function when the command is assignto
bool assigntoExecute(const char *program, vector<const char*> arguments);
	// Checks if the variable exists
bool variableExists(string variableName);
	// Reads the temporary data file for assignto
string readDataFile();
	// Gets arguments to run a function
vector<const char*> getArgs( vector<Token> &parsed, const char * path);